Avr 5805
Anybody out there who is able to help with a question on the Denon
AVR 5805?
Last weekend the unit suddenly stopped output to the speakers.
The part of the movie being watched was not even overly loud.
For several reasons i can not afford right now to bring the unit to
a repair center, plus every time it ends up costing about $ 600.00 .
So i got the repair manual and started to check it out.
I found that the main transformer (which runs the output amps) did not get any power. The power to it is controlled by a relay. The logic circuit controlling the relay have several inputs. Two of these signals are called "POWER" and the second one is called "AC_P.DOWN". The later seems to be used to shut things down.
Does anybody know under what circumstances that signal will be send out?
Thanks Gernot javascript:smilie('
')
Anybody out there who is able to help with a question on the Denon
AVR 5805?
Last weekend the unit suddenly stopped output to the speakers.
The part of the movie being watched was not even overly loud.
For several reasons i can not afford right now to bring the unit to
a repair center, plus every time it ends up costing about $ 600.00 .
So i got the repair manual and started to check it out.
I found that the main transformer (which runs the output amps) did not get any power. The power to it is controlled by a relay. The logic circuit controlling the relay have several inputs. Two of these signals are called "POWER" and the second one is called "AC_P.DOWN". The later seems to be used to shut things down.
Does anybody know under what circumstances that signal will be send out?
Thanks Gernot javascript:smilie('
')hi,
these things get there shut down signal for the mains from various places, some from the processor, these include power amp overload, dc protect, temperature over load, power supply fault etc,
unless you are familar with all this i would leave well alone untill you finances alows you to send it for proffesional repair
good luck with it
these things get there shut down signal for the mains from various places, some from the processor, these include power amp overload, dc protect, temperature over load, power supply fault etc,
unless you are familar with all this i would leave well alone untill you finances alows you to send it for proffesional repair
good luck with it
I REi repair a lot of denons where i work. denon (and other home theater multichannel receivers) repairs aren't for the faint of heart. 4 things are absolutely neccesary when working on these:
1) a systematic approach to troubleshooting these receivers. gone are the days when a receiver section could be troubleshot as a separate entity. these receivers now have a central nervous system, and the various sections interact through the cpu. protection problems can be due to anything from a shorted output stage to a missing supply voltage, to a loose ground screw somewhere (usually on the back panel)
2)mechanical aptitude. denon especially so, since the larger the receiver, the more complex the 3D puzzle inside.
3) lots of patience. see #2, and the fact that many times, the only indication you get of a problem is shutdown. some manufacturers have a protect message for overcurrent, dc, or power supply problems, but most do not.
4) the proper test equipment. a good meter, an o-scope, a signal source, these are a good start. for troubleshooting cpu problems the scope is essential
more l8r
1) a systematic approach to troubleshooting these receivers. gone are the days when a receiver section could be troubleshot as a separate entity. these receivers now have a central nervous system, and the various sections interact through the cpu. protection problems can be due to anything from a shorted output stage to a missing supply voltage, to a loose ground screw somewhere (usually on the back panel)
2)mechanical aptitude. denon especially so, since the larger the receiver, the more complex the 3D puzzle inside.
3) lots of patience. see #2, and the fact that many times, the only indication you get of a problem is shutdown. some manufacturers have a protect message for overcurrent, dc, or power supply problems, but most do not.
4) the proper test equipment. a good meter, an o-scope, a signal source, these are a good start. for troubleshooting cpu problems the scope is essential
more l8r
i can tell you some of the common failure items in denon receivers:
3 terminal regulators, such as 7815 and 7915's..... especially the 15 volt ones. denon also uses a 9v rail for some of their DSP and HDMI boards. they drop 32 volts down to 9 by cascading 7818, 7815, and 7809 regulators. these 3 regulators, if they use them are NOT heatsinked and fail often. the +/-15V rails use 7815 and 7915 regulators and these fail often, even though they are heatsinked.
the failure here will be power on for a few seconds and then off. if there is a power status LED it will blink twice a second.
output devices. these are common failure items, but usually when the amps are being pushed at about half power for extended periods. there was also a problem with some of their amps using the wrong bias transistor, which didn't track the output devices well thermally. failure mode, same as above, except the LED may blink once a second or once every 2 seconds.
i recently saw an amp that had ALL of it's amps latched to the rail. the problem was a transistor that is used as a capacitance multiplier on one of the rails for the diff amp (LTP) and VAS stages. if the transistor or the 4.7 ohm resistor feeding it are open, all of the amps latch to the opposite rail and the unit goes into protect mode.
failure mode here, the same as the output devices
relay coils. the power relay can develop a shorted turn or burn open. either way the relay doesn't operate at all, even though your AV_RLY signal goes high.
CPU chip. no response at all to the power switch. you will have +5V standby supply and /PWR_SW signal from the front panel board, but no AC_RLY signal.
standby power transformer or other standby supply problem. you will have no action from the relay, no STBY +5 at the CPU.
if you have a blown AC line (mains) fuse, check the output devices.
generally older denons used the SPEAKER A and SPEAKER B buttons to access the protection override. hold them both down for 5 seconds, or hold them down and turn on the master power button (the one that operates a real power switch)
HTH
3 terminal regulators, such as 7815 and 7915's..... especially the 15 volt ones. denon also uses a 9v rail for some of their DSP and HDMI boards. they drop 32 volts down to 9 by cascading 7818, 7815, and 7809 regulators. these 3 regulators, if they use them are NOT heatsinked and fail often. the +/-15V rails use 7815 and 7915 regulators and these fail often, even though they are heatsinked.
the failure here will be power on for a few seconds and then off. if there is a power status LED it will blink twice a second.
output devices. these are common failure items, but usually when the amps are being pushed at about half power for extended periods. there was also a problem with some of their amps using the wrong bias transistor, which didn't track the output devices well thermally. failure mode, same as above, except the LED may blink once a second or once every 2 seconds.
i recently saw an amp that had ALL of it's amps latched to the rail. the problem was a transistor that is used as a capacitance multiplier on one of the rails for the diff amp (LTP) and VAS stages. if the transistor or the 4.7 ohm resistor feeding it are open, all of the amps latch to the opposite rail and the unit goes into protect mode.
failure mode here, the same as the output devices
relay coils. the power relay can develop a shorted turn or burn open. either way the relay doesn't operate at all, even though your AV_RLY signal goes high.
CPU chip. no response at all to the power switch. you will have +5V standby supply and /PWR_SW signal from the front panel board, but no AC_RLY signal.
standby power transformer or other standby supply problem. you will have no action from the relay, no STBY +5 at the CPU.
if you have a blown AC line (mains) fuse, check the output devices.
generally older denons used the SPEAKER A and SPEAKER B buttons to access the protection override. hold them both down for 5 seconds, or hold them down and turn on the master power button (the one that operates a real power switch)
HTH
Thanks to all of you.
Thanks to all of you guy's.
First I want to introduce myself (I forget that at my first posting)
Is was born in Germany after WW II, spend some time in the GAF.
Currently, my job is infrared test engineer and I worked on the last Hubble upgrade the WFC III (wide field camera 3) that is 1 of the 2 instruments we made for the Hubble, and we are still working on the James Webb Space telescope (we made all FPA's for the instrument, NIRSPEC, NIRCAM and FGS and the assics ).
Other customers are the University of Hawaii, ESO (European southern observatory) and last not least the government
Besides my work I love cars, high-end video, boating and I don't have enough time for pretty much everything else.
Enough about me. Back to the 5805.
The longer I work (or better investigate) the problem the more respect I got for the people of Denon. The design is just amazing.
As I am following the diff. signals forward and backward thru all the diff. boards and all the internal connections, I came to 2 conclusions, the first one is, that it is impossible to check everything since you can't get to it and once you dismantled the unit you can't test it anymore.
The second is pretty much straightforward just locking at the logic the boards etc and that is, that has to be diagnostic software for
testing the unit. And the connection for that is under the cover on the front panel.
So, for the time beiing, I am keep looking and I will see what I can find out regarding the software.
Gernot
Thanks to all of you guy's.
First I want to introduce myself (I forget that at my first posting)
Is was born in Germany after WW II, spend some time in the GAF.
Currently, my job is infrared test engineer and I worked on the last Hubble upgrade the WFC III (wide field camera 3) that is 1 of the 2 instruments we made for the Hubble, and we are still working on the James Webb Space telescope (we made all FPA's for the instrument, NIRSPEC, NIRCAM and FGS and the assics ).
Other customers are the University of Hawaii, ESO (European southern observatory) and last not least the government
Besides my work I love cars, high-end video, boating and I don't have enough time for pretty much everything else.
Enough about me. Back to the 5805.
The longer I work (or better investigate) the problem the more respect I got for the people of Denon. The design is just amazing.
As I am following the diff. signals forward and backward thru all the diff. boards and all the internal connections, I came to 2 conclusions, the first one is, that it is impossible to check everything since you can't get to it and once you dismantled the unit you can't test it anymore.
The second is pretty much straightforward just locking at the logic the boards etc and that is, that has to be diagnostic software for
testing the unit. And the connection for that is under the cover on the front panel.
So, for the time beiing, I am keep looking and I will see what I can find out regarding the software.
Gernot
the connector behind the front panel is for updating the firmware.
denons that old do not have diagnostic software, just whether the power/standby LED flashes fast or slow. even the newest ones (-09 models for 2009) though they claim to have a test mode, it doesn't work like it says in the service manual, so it must not have got implemented in firmware yet.
any problem the unit has OTHER THAN the standby power supply or the CPU chip will allow the power relay to activate for a few seconds. if the relay doesn't come on at all, it's either your standby power supply (the little transformer and diodes on the board where the power relay is are where this comes from), or the CPU isn't working (requiring a replacement of the DSP board)
denons that old do not have diagnostic software, just whether the power/standby LED flashes fast or slow. even the newest ones (-09 models for 2009) though they claim to have a test mode, it doesn't work like it says in the service manual, so it must not have got implemented in firmware yet.
any problem the unit has OTHER THAN the standby power supply or the CPU chip will allow the power relay to activate for a few seconds. if the relay doesn't come on at all, it's either your standby power supply (the little transformer and diodes on the board where the power relay is are where this comes from), or the CPU isn't working (requiring a replacement of the DSP board)
Denon 5805
Hello Unclejed613
thanks for your response, it will give me a good idea what to look for.
Here is what I know so far (besides other bits and pieces). The relay to turn on the main transformer never receives the signal the power up cycle.
I am reasoning that, if something is wrong with the power amps,
and the for the problem to be sensed by the protective circuitry, the power has to be turned on at least briefly.
So I figure that something else is causing that problem.
By the way the speaker are disconnected since the beginning of the issue.
My biggest problem at this time is actually related to the PDF files, I don't have a monitor big enough to keep the display at a magnification large enough to read the "small print", so I end up switching between schematics all the time.
Hello Unclejed613
thanks for your response, it will give me a good idea what to look for.
Here is what I know so far (besides other bits and pieces). The relay to turn on the main transformer never receives the signal the power up cycle.
I am reasoning that, if something is wrong with the power amps,
and the for the problem to be sensed by the protective circuitry, the power has to be turned on at least briefly.
So I figure that something else is causing that problem.
By the way the speaker are disconnected since the beginning of the issue.
My biggest problem at this time is actually related to the PDF files, I don't have a monitor big enough to keep the display at a magnification large enough to read the "small print", so I end up switching between schematics all the time.
next to the power relay should be a small glass diode. measuring from either lead of this diode to ground you should have about 12V dc. if you have 12V dc there, look for a connector on the same board that usually has 4 to 6 wires. they usually have printing on the circuit board indicating the labels of the pins of the connector. one of the pin labels will say +5 S, or +12 S. check the voltage on that pin. it should agree with the pin label. if you have your standby voltage there, go to the ribbon cable going from the front panel to the CPU board. look for pin labels for that connector and measure the pin marked PSW or PWR_ON, or something similar. you should see +5V there that drops to between 0 and 1V when you press the standby/on switch. if you find all of these measurements to be fine, then you need a new CPU board. if any of the first two voltages i mentioned are missing, the standby supply is bad, and you either have a bad standby transformer (the small one on the power relay board) or something else is bad on the power relay board. if you don't have the PSW signal, you could have a problem with the front panel board or again, a problem with the CPU.
i am going to ask the obvious here, but i've overlooked it myself..... did you check the fuses on the power relay board?.... (with power cord unplugged of course).... these units also normally have a "real" power switch in addition to the "soft" switch, and they can go bad as well, killing AC to the power relay board.
i am going to ask the obvious here, but i've overlooked it myself..... did you check the fuses on the power relay board?.... (with power cord unplugged of course).... these units also normally have a "real" power switch in addition to the "soft" switch, and they can go bad as well, killing AC to the power relay board.
Again thanks,
I hope that you are not right, with the CPU board. One thing I have to mention is, that everything else works. You can get to all menus and chose from all different inputs etc. So, there is a chance that the CPU is OK.
Tonight I am going to follow you tip and check the diode and the supply voltages.
The fuse close to the relay was the first thing I checked, and the fuse was OK.
On the board above the voltage regulators are 10 fuses and all are fine. I guess that something is preventing the main transformer to start since even HDMI transfer and up converting works.
Gernot
I hope that you are not right, with the CPU board. One thing I have to mention is, that everything else works. You can get to all menus and chose from all different inputs etc. So, there is a chance that the CPU is OK.
Tonight I am going to follow you tip and check the diode and the supply voltages.
The fuse close to the relay was the first thing I checked, and the fuse was OK.
On the board above the voltage regulators are 10 fuses and all are fine. I guess that something is preventing the main transformer to start since even HDMI transfer and up converting works.
Gernot
i thought you said there's no power at all.....
that's different..... if you have a display, then the cpu and everything i've suggested so far is fine......
you mean there's no audio......
the display and everything works off of the main transformer, so the power relay IS turning on....
check the fuses for the power amp's power supply, they should be right near the big bridge rectifiers and big capacitors. actually the easiest thing to check are the DC voltages on the output transistors. check the voltages on the metal tabs of the output transistors. the transistors with part numbers beginning with A or B should have a negative voltage on them of 35 to 55. the transistors with part numbers beginning with C or D should have a positive voltage on them approximately numerically identical (except it's positive, not negative). if one or both of those voltages is missing, you have a problem with the amp supply. i'll check back in tomorrow to see what you find..... in the meantime i can see if i can find the manual so i can be a bit more specific as ro what to check.
that's different..... if you have a display, then the cpu and everything i've suggested so far is fine......
you mean there's no audio......
the display and everything works off of the main transformer, so the power relay IS turning on....
check the fuses for the power amp's power supply, they should be right near the big bridge rectifiers and big capacitors. actually the easiest thing to check are the DC voltages on the output transistors. check the voltages on the metal tabs of the output transistors. the transistors with part numbers beginning with A or B should have a negative voltage on them of 35 to 55. the transistors with part numbers beginning with C or D should have a positive voltage on them approximately numerically identical (except it's positive, not negative). if one or both of those voltages is missing, you have a problem with the amp supply. i'll check back in tomorrow to see what you find..... in the meantime i can see if i can find the manual so i can be a bit more specific as ro what to check.
Hi,
Sorry to hijack this thread for a moment, but I have a question for unclejed...
Firstly, I have some electronics experience, and I also have the service manual for the Denon, but I've got a bit of a strange problem with it which I thought you might have come across before...
OK... I have a Denon AVC-A11SR (which I brought as "faulty" around 4 years ago.) The center channel power transistors (and a few pre-amp / bias passives) were blown, so I replaced those and have been happily using the amp for all these years...
Recently however, I've been using my DIY amp (RevC), and when I came to try the Denon again, it had a "crackling sound" fault on the center channel. This was due to dry solder joints on the medium-sized transistors in the bias circuitry (2SA1546 etc.) - These transistors obviously get warm, as the PCB is starting to go brown.
So, I resoldered pretty much EVERY component in the center channel, then resoldered the bias transistors and other components on all the other channels as some were also starting to dry-joint...
Obviously I always discharge both of the main power caps via a 1K resistor after unplugging, 'cos they can pack quite a big punch. The problem is, discharging through 1K is SLOW, I got bored at around 20 volts and I thought "oh, that's enough"! So, when I was re-connecting everything after repairing the solder joints, the spade connector for negative rail shorted across to the +15V jumper wire and discharged around -20V into it!
OK, so the amp still powers up, all the fuses and the usual voltages (that I can reach) seem to measure fine (+/-15V, +/-63V, +20V, +5V)....
But, the front left and right channels are much quieter than the center channel (around 12dB). Also, the sound for the surround-back channels can be heard faintly through the respective surround channels??
This happens with both the test tone and the pre-inputs, but I've scoped the DAC outputs on the DSP board, and they're all perfectly normal (all the same level on the test tone, and no inter-mixing)...
The only place I could see on the service diagram where the signals could mix is via the TC9274N-017 chip. So, I purchase a new one and replaced that too (£24 !!). Still the same problem? (btw, "Tone defeat" is enabled).
So, unless it's the limiter diodes or the volume control chips causing the problem, I'm a bit stumped. Although I can't see how it would be possible for the channels to inter-mix via the volume control chips?? I'm not sure about it being a muting issue, but it's possible.
The other problem is not being able to physically test anything while the amp is running because all of the DSP and input boards fit together in a big 3D cube type affair (like you said earlier).
It could be that the Flash in one of the CPU chips got corrupted slightly, and it's not controlling the "mode select" chip properly? (TC9274N-017). The amp has also been reset, and the levels have been set again (to force a Flash write).
The problem wasn't happening until I shorted the rail across, so it's likely to be a problem on a device powered by +15V. I've even replaced most of the relevent signal opamps.
The only way ahead that I can think of is to solder some test wires on to various points to extend them outside the big "cube". I can then test where the signals are going wrong.
Have you ever heard of this type of issue before?
I'm more than happy to help with anyone else's repairs. I don't currently have any other suggestions about the 5805 atm though. (other than what you guys have already said).
OzOnE.
Sorry to hijack this thread for a moment, but I have a question for unclejed...
Firstly, I have some electronics experience, and I also have the service manual for the Denon, but I've got a bit of a strange problem with it which I thought you might have come across before...
OK... I have a Denon AVC-A11SR (which I brought as "faulty" around 4 years ago.) The center channel power transistors (and a few pre-amp / bias passives) were blown, so I replaced those and have been happily using the amp for all these years...
Recently however, I've been using my DIY amp (RevC), and when I came to try the Denon again, it had a "crackling sound" fault on the center channel. This was due to dry solder joints on the medium-sized transistors in the bias circuitry (2SA1546 etc.) - These transistors obviously get warm, as the PCB is starting to go brown.
So, I resoldered pretty much EVERY component in the center channel, then resoldered the bias transistors and other components on all the other channels as some were also starting to dry-joint...
Obviously I always discharge both of the main power caps via a 1K resistor after unplugging, 'cos they can pack quite a big punch. The problem is, discharging through 1K is SLOW, I got bored at around 20 volts and I thought "oh, that's enough"! So, when I was re-connecting everything after repairing the solder joints, the spade connector for negative rail shorted across to the +15V jumper wire and discharged around -20V into it!
OK, so the amp still powers up, all the fuses and the usual voltages (that I can reach) seem to measure fine (+/-15V, +/-63V, +20V, +5V)....
But, the front left and right channels are much quieter than the center channel (around 12dB). Also, the sound for the surround-back channels can be heard faintly through the respective surround channels??
This happens with both the test tone and the pre-inputs, but I've scoped the DAC outputs on the DSP board, and they're all perfectly normal (all the same level on the test tone, and no inter-mixing)...
The only place I could see on the service diagram where the signals could mix is via the TC9274N-017 chip. So, I purchase a new one and replaced that too (£24 !!). Still the same problem? (btw, "Tone defeat" is enabled).
So, unless it's the limiter diodes or the volume control chips causing the problem, I'm a bit stumped. Although I can't see how it would be possible for the channels to inter-mix via the volume control chips?? I'm not sure about it being a muting issue, but it's possible.
The other problem is not being able to physically test anything while the amp is running because all of the DSP and input boards fit together in a big 3D cube type affair (like you said earlier).
It could be that the Flash in one of the CPU chips got corrupted slightly, and it's not controlling the "mode select" chip properly? (TC9274N-017). The amp has also been reset, and the levels have been set again (to force a Flash write).
The problem wasn't happening until I shorted the rail across, so it's likely to be a problem on a device powered by +15V. I've even replaced most of the relevent signal opamps.
The only way ahead that I can think of is to solder some test wires on to various points to extend them outside the big "cube". I can then test where the signals are going wrong.
Have you ever heard of this type of issue before?
I'm more than happy to help with anyone else's repairs. I don't currently have any other suggestions about the 5805 atm though. (other than what you guys have already said).
OzOnE.
all of the analog part of the circuitry works off of the +/- 15V rails. it's possible you damaged either the DAC filters (usually op amps with lots of small electrolytic caps around them on the DSP Board) or the mute circuit. the mute circuit is usually a control line going to the bases of the mute transistors at the inout to each amp. there should be a -12V signal on the bases of the mute transistors (usually). you might also have a diode somewhere in the +/- 15V rails on the DSP board or a zener or transistor being used as a noise filter. that could be bad. another possibility is that the feedback DC correction caps in the amps are bad, dropping the gains of the amplifiers. you said you saw a lot of thermal damage to the solder, so dried out caps is another possible problem. sometimes (especially in denon receivers) there are more than one source of the analog (+/- 15V) rails, so you may actually have another bad regulator somewhere else.
the volume control chip is another possibility. you can bypass it by connecting signal in to signal out to troubleshoot this.
the volume control chip is another possibility. you can bypass it by connecting signal in to signal out to troubleshoot this.
Hi,
Thanks for the reply. There are a lot of good pointers there. I never actually thought of bypassing the volume control chips. I can then input a tone and check the relative levels (input at a very low level of course!
)
Just a quick thought for Gernot - try testing the voltage output on all the voltage regulators. The output pin is usually marked ("O") on my Denon.
I think the volume control IC's are simple switched-resistor things (TC9549N), so it should be OK to bypass to the outputs.
What I have noticed is that I hear fairly loud mains hum if I touch the tops of the capacitors on the power amp boards. I guess this happens in some high-gain circuits, but it's a bit disconcerting.
Yesterday I tried analysing the data signals to the "function select" IC (new replacement). My scope doesn't have digital storage and the data is too fast to catch, so I tried hooking up to TFLA instead...
http://tfla-01.berlios.de/
Unfortunately I think the data is still too fast to capture - I only saw a couple of blips on the strobe line and not much else. I do think the function select IC must be working to an extent, otherwise I imagine that many signals would be mixed at all times (eg. the pre-inputs / DACs etc.).
Of course, there are many things I could have zapped, so I'll keep plodding on and I'll try bypassing some of those things you suggested. It's too bad I'll need to solder wires onto the board, then re-assemble most of the amp to test it though. Strange that the Denon has a huge access panel underneath, but you still need a factory jig to test the boards properly??
It's a mystery as to why the signals sound mixed?... I've attached a few snapshots of the service diagrams so you can see how the function select and mute stuff works. Don't worry, I don't want to take up too much of everyone's time for the solution, I just thought someone might find the diagrams interesting.
There are only places I can see where the signals could inter-mix - the function select chip (replaced), the mute transistors, or the limiter diodes. I guess any circuit in the signal path which share a common control signal could cause the problem.
What I can say is that the test tone for the surround-back channels can be heard on the respective surround channels at almost the same volume. ie. the display shows SBR and you can hear it from the SR channel (only it's a couple of dB's lower than the SR channel's own test tone.)
On the attached diagram, you can see on the function select chip (IC113) that the surround channels are routed to the "A+B" input, so the surround channels can be cloned on the surround-back channels. This would explain the mixing problem, but I don't know of an easy way of testing the control bus without a decent scope.
The "quickest" test I could try would be to remove IC113 again and temporarily bypass the switches for the pre-inputs or DAC outputs. (Good job I bought a soldering iron with a built-in desolder pump recently).
btw, You can see at the top of the diagram where the DAC outputs and pre-inputs are routed to the function select chip. The pre-inputs are simply buffered on a separate board and the DAC's seem to test fine.
You can also just see where the front channels are mixed and filtered (IC116) for the subwoofer output (in analog DIRECT mode) - this is something I often wondered about until I got the service manual. Just below IC116, another opamp (not shown) does the HPF when the speakers are set to "small".
I can't quite figure out how the limiter circuit works, but hey. I could just try removing the limiter diodes, or would that cause big problems?
Here are the diagrams (zipped bitmaps - to preserve quality)...
http://www.filesavr.com/denonavc-a11srdiagramstuff
OzOnE.
Thanks for the reply. There are a lot of good pointers there. I never actually thought of bypassing the volume control chips. I can then input a tone and check the relative levels (input at a very low level of course!
)Just a quick thought for Gernot - try testing the voltage output on all the voltage regulators. The output pin is usually marked ("O") on my Denon.
I think the volume control IC's are simple switched-resistor things (TC9549N), so it should be OK to bypass to the outputs.
What I have noticed is that I hear fairly loud mains hum if I touch the tops of the capacitors on the power amp boards. I guess this happens in some high-gain circuits, but it's a bit disconcerting.
Yesterday I tried analysing the data signals to the "function select" IC (new replacement). My scope doesn't have digital storage and the data is too fast to catch, so I tried hooking up to TFLA instead...
http://tfla-01.berlios.de/
Unfortunately I think the data is still too fast to capture - I only saw a couple of blips on the strobe line and not much else. I do think the function select IC must be working to an extent, otherwise I imagine that many signals would be mixed at all times (eg. the pre-inputs / DACs etc.).
Of course, there are many things I could have zapped, so I'll keep plodding on and I'll try bypassing some of those things you suggested. It's too bad I'll need to solder wires onto the board, then re-assemble most of the amp to test it though. Strange that the Denon has a huge access panel underneath, but you still need a factory jig to test the boards properly??
It's a mystery as to why the signals sound mixed?... I've attached a few snapshots of the service diagrams so you can see how the function select and mute stuff works. Don't worry, I don't want to take up too much of everyone's time for the solution, I just thought someone might find the diagrams interesting.
There are only places I can see where the signals could inter-mix - the function select chip (replaced), the mute transistors, or the limiter diodes. I guess any circuit in the signal path which share a common control signal could cause the problem.
What I can say is that the test tone for the surround-back channels can be heard on the respective surround channels at almost the same volume. ie. the display shows SBR and you can hear it from the SR channel (only it's a couple of dB's lower than the SR channel's own test tone.)
On the attached diagram, you can see on the function select chip (IC113) that the surround channels are routed to the "A+B" input, so the surround channels can be cloned on the surround-back channels. This would explain the mixing problem, but I don't know of an easy way of testing the control bus without a decent scope.
The "quickest" test I could try would be to remove IC113 again and temporarily bypass the switches for the pre-inputs or DAC outputs. (Good job I bought a soldering iron with a built-in desolder pump recently).
btw, You can see at the top of the diagram where the DAC outputs and pre-inputs are routed to the function select chip. The pre-inputs are simply buffered on a separate board and the DAC's seem to test fine.
You can also just see where the front channels are mixed and filtered (IC116) for the subwoofer output (in analog DIRECT mode) - this is something I often wondered about until I got the service manual. Just below IC116, another opamp (not shown) does the HPF when the speakers are set to "small".
I can't quite figure out how the limiter circuit works, but hey. I could just try removing the limiter diodes, or would that cause big problems?
Here are the diagrams (zipped bitmaps - to preserve quality)...
http://www.filesavr.com/denonavc-a11srdiagramstuff
OzOnE.
EDIT: I meant to edit the above post with some other suggestions for Gernot, but the evil 30-minute timeout hit me. Here are some other things to try....
I would assume that most Denon amps would shut down to standby or display an error if any of the usual faults were detected (overcurrent / DC / temperature), so it does sound like you have a voltage missing somewhere.
I can suggest a few other things you could test but this is ALL based on my A11SR....
Can you hear ANY of the relay's working btw? - the relay(s) for the main transformer are likely to get their supply from small sub-transformers (which usually supply the standby voltage and the CPU supply). If it's not a usual protection fault, it could be due to one of these supplies....
On the A11SR, the two small sub-transformers are powered from the mains at all times, the CPU transfomer supplies 6V (M6V) which also pulls up the the P.DOWN signal when the 6V supply is stable (well, when it's above a zener voltage I think), so the main relay(s) won't switch on unless the CPU supply is over a certain threshold.
Also, the rectified 11.6V supply (going into the 6V regulator) is used to power the main relays. There are usually two main relays which are powered up in quick sequence (to limit the initial inrush current on the main transfomer by passing the mains via the first relay and some large 10W resistors.)
What voltage are the actual POWER and P.DOWN signals at?
Anyway, I'm sure your CPU supply must be working if the on-screen menus are working? On the A11SR, the front panel display's filament supply also comes from the small sub-transformer (unlike older / smaller Denon models), so it IS possible to have the front panel and on-screen menus working without the main power transfomer turned on. I'm guessing the 5805 works the same way (eg. for multi-room etc.)
I would test everything around those small transformers first and make sure the control circuit for the main relays have power etc.
OzOnE.
I would assume that most Denon amps would shut down to standby or display an error if any of the usual faults were detected (overcurrent / DC / temperature), so it does sound like you have a voltage missing somewhere.
I can suggest a few other things you could test but this is ALL based on my A11SR....
Can you hear ANY of the relay's working btw? - the relay(s) for the main transformer are likely to get their supply from small sub-transformers (which usually supply the standby voltage and the CPU supply). If it's not a usual protection fault, it could be due to one of these supplies....
On the A11SR, the two small sub-transformers are powered from the mains at all times, the CPU transfomer supplies 6V (M6V) which also pulls up the the P.DOWN signal when the 6V supply is stable (well, when it's above a zener voltage I think), so the main relay(s) won't switch on unless the CPU supply is over a certain threshold.
Also, the rectified 11.6V supply (going into the 6V regulator) is used to power the main relays. There are usually two main relays which are powered up in quick sequence (to limit the initial inrush current on the main transfomer by passing the mains via the first relay and some large 10W resistors.)
What voltage are the actual POWER and P.DOWN signals at?
Anyway, I'm sure your CPU supply must be working if the on-screen menus are working? On the A11SR, the front panel display's filament supply also comes from the small sub-transformer (unlike older / smaller Denon models), so it IS possible to have the front panel and on-screen menus working without the main power transfomer turned on. I'm guessing the 5805 works the same way (eg. for multi-room etc.)
I would test everything around those small transformers first and make sure the control circuit for the main relays have power etc.
OzOnE.
actually the FL display works off of the main transformer on newer denons. if his amp has power to the display, but no errors to cause shutdown, he might have a problem in his signal chain. i don't know because he hasn't posted a reply to my last post to him.
if you are getting signal mixing, it is possible the mute circuit is doing it, but i can't say for sure because i have never seen it happen. in theory, though, if you have one or more transistors in the mute circuit shorted C-B, it's possible that some signal could be getting redistributed through the mute lines. you need to check this with signal injection and a scope to find out just where these signals are getting mixed. the caps you are touching and getting hum pickup are dc blocking caps in the signal path. they make very good test points for signal injection and monitoring with a scope. oops, you got me to spill one of my trade secrets, i'll have to send uncle frankie out to your house with his cement truck..... what size shoes do you wear?
if you are getting signal mixing, it is possible the mute circuit is doing it, but i can't say for sure because i have never seen it happen. in theory, though, if you have one or more transistors in the mute circuit shorted C-B, it's possible that some signal could be getting redistributed through the mute lines. you need to check this with signal injection and a scope to find out just where these signals are getting mixed. the caps you are touching and getting hum pickup are dc blocking caps in the signal path. they make very good test points for signal injection and monitoring with a scope. oops, you got me to spill one of my trade secrets, i'll have to send uncle frankie out to your house with his cement truck..... what size shoes do you wear?
Hi,
Please ignore most of what I said previously - I realized only last night that I hadn't actually checked to see if the pre-inputs were being mixed continously after I'd installed the new function chip. It turns out that they ARE (even with the test tone running)!
So, this means that the function chip does actually have all the switches closed at the same time. Directly after that, I did the most basic check I should have done in the first place - I tested the data bus pins with the voltmeter and found the FTCLK pin to be shorted to ground! (Function / Tone CLocK).
(According to the datasheet for the function switch, it does actually leave all the switches closed on reset. Obviously with the clock pin shorted to ground, the switches never get enabled properly.)
At first I thought that the short was confined to the audio input board, but unfortunately it seems that the CPU pin itself is shorted (on the DSP board). This happens to be a very difficult part to get hold of because the software is pre-programmed into the flash. (I think)
There are no other components along the FTCLK PCB track, so it must be the pin itself (reads around 9 ohms), doh!
Oh well, you can still send uncle Frankie round to teach me a lesson for my stupidity (for zapping it in the first place, and for not finding the fault faster). We have a convenient pier here too!
I mean, of all the damn components to fry. Even if it was one of the SHARC DSP chips it would have been easier to get hold of a replacement.
I've seen the CPU chip listed on a few sites, but not with exact part number for the A11SR. Oh well, I'll find something in the end.
The AVR-4802 and AVR-5800 apparently have a similar DSP board, but it looks like the firmware is different. The following site says things like "RED", which I guess means the spot of paint they add to each chip after flashing the firmware. On my chip (IC802), it has a WHITE spot?...
http://www.encompassparts.com/products/?GEN5015
You don't happen to know if you could get hold of the firmware for the chip? And would it be possible to flash it via the serial port, or do the chips need some sort of bootloader to be pre-programmed first?
I see that the DSP board also has some DIP switches on which appear to switch the RS232 port between the primary and secondary CPU chips - is it possible to read the firmware via the RS232 port so it can be programmed into a new chip or does this also require the use of Denon's "secret" software commands?
This is another reason why I'm disheartened by commercial amps - once I get my DIY amp working with 7.1 and Dolby / DTS decoding, it will be much easier to service and upgrade in the future.
Thanks again for your time. I'll keep an eye on this thread once Gernot appears again.
Cheers,
OzOnE.
Please ignore most of what I said previously - I realized only last night that I hadn't actually checked to see if the pre-inputs were being mixed continously after I'd installed the new function chip. It turns out that they ARE (even with the test tone running)!
So, this means that the function chip does actually have all the switches closed at the same time. Directly after that, I did the most basic check I should have done in the first place - I tested the data bus pins with the voltmeter and found the FTCLK pin to be shorted to ground! (Function / Tone CLocK).
(According to the datasheet for the function switch, it does actually leave all the switches closed on reset. Obviously with the clock pin shorted to ground, the switches never get enabled properly.)
At first I thought that the short was confined to the audio input board, but unfortunately it seems that the CPU pin itself is shorted (on the DSP board). This happens to be a very difficult part to get hold of because the software is pre-programmed into the flash. (I think)
There are no other components along the FTCLK PCB track, so it must be the pin itself (reads around 9 ohms), doh!
Oh well, you can still send uncle Frankie round to teach me a lesson for my stupidity (for zapping it in the first place, and for not finding the fault faster). We have a convenient pier here too!
I mean, of all the damn components to fry. Even if it was one of the SHARC DSP chips it would have been easier to get hold of a replacement.
I've seen the CPU chip listed on a few sites, but not with exact part number for the A11SR. Oh well, I'll find something in the end.
The AVR-4802 and AVR-5800 apparently have a similar DSP board, but it looks like the firmware is different. The following site says things like "RED", which I guess means the spot of paint they add to each chip after flashing the firmware. On my chip (IC802), it has a WHITE spot?...
http://www.encompassparts.com/products/?GEN5015
You don't happen to know if you could get hold of the firmware for the chip? And would it be possible to flash it via the serial port, or do the chips need some sort of bootloader to be pre-programmed first?
I see that the DSP board also has some DIP switches on which appear to switch the RS232 port between the primary and secondary CPU chips - is it possible to read the firmware via the RS232 port so it can be programmed into a new chip or does this also require the use of Denon's "secret" software commands?
This is another reason why I'm disheartened by commercial amps - once I get my DIY amp working with 7.1 and Dolby / DTS decoding, it will be much easier to service and upgrade in the future.
Thanks again for your time. I'll keep an eye on this thread once Gernot appears again.
Cheers,
OzOnE.
AVR 5800 - HELP
Hi, I just bought this AVR-5800 and need some help. The machine is awesome. Works just fine except no sound when I try to use the 5/7 channel stereo, Dolby, THX, Cinema modes. I get awesome sound when I connect to Stereo/Direct and Pure Direct Modes. In the garage, you see I have 3 speakers connected (FL, FR, C) and an iPod in DVD input. The music plays in the three modes I just mentioned but the moment I press the other modes (5 channel stereo, Cinema, THX, Dolby, etc) nothing. Silence. Then I thought OK it needs a Digital signal so I went to the living room and disconnected my Pioneer and plugged all my speakers (took me an hour) - FL, FR, C, SW, SR, SL, SBR, SBL - and I connected my Denon DVD and Comcast box via Optical - checked everything - inputs, speaker config, SB config - same problem. I only get sound thru the Analog iPod now connected to the CD input. So the Digital signal was not passing thru to Stereo/Direct/Pure Direct modes. I opened the top - clean - looks good if you look at like 1,000 transistors - all the 8A fuses up top, about 8or them were fine. OK. Went to the left and right panels - clean too - so it seems. Then I went underneath, bottom panel and viopla - found 2 fuses there on a Board - One glass 8A like the top and a ceramic 12A - both 125V. just to be sure I replaced the Ceramic with a 12A 250V new fuse and the glass 8A was fine as is and back to sqaure one - same issue. The I notices this board and the transformer (see pic with the model number 2336333009 and it has been soldered into the board and one one side there are three holes that looked like the solder fell off and I convinced myself it was this part that was causing the problem. not sure what it does. SO I decide to pull the board out and did successfully. Looking at it closeley you can see some brown burning type stain on several of the thingies. The biggest bruise is on a black chip like devise with a red amrker on it. I think this is bad and maybe some of the others or the massive transistor is not welde on right and possibly failed. When you hold the board up in the light it seems the holes are intentional since the holes do not lead to any "channels" on the green board. I am thinking the components have failed on this board and caused a cutoff to the DSP which looks clean. Can someone tell me what this transformer does. the power leads yell and white wires come straight from the power supply main plug and another three go to additional pwer supplies that you can plug to the back of the receiver. I paid $400 of this unit and I am thinking the board may cost another 200 or I just test and replace the transistor thingies. Not sure what to do since I am not an engineer. I'm an HR guy actually! Hee. Hee. I looked up the transformer part on Encompass - a Denon parts site and it's about 28 bucks but they don't have a pic of it. Any advice from pros out there will be much appreciated. Thanks.
Hi, I just bought this AVR-5800 and need some help. The machine is awesome. Works just fine except no sound when I try to use the 5/7 channel stereo, Dolby, THX, Cinema modes. I get awesome sound when I connect to Stereo/Direct and Pure Direct Modes. In the garage, you see I have 3 speakers connected (FL, FR, C) and an iPod in DVD input. The music plays in the three modes I just mentioned but the moment I press the other modes (5 channel stereo, Cinema, THX, Dolby, etc) nothing. Silence. Then I thought OK it needs a Digital signal so I went to the living room and disconnected my Pioneer and plugged all my speakers (took me an hour) - FL, FR, C, SW, SR, SL, SBR, SBL - and I connected my Denon DVD and Comcast box via Optical - checked everything - inputs, speaker config, SB config - same problem. I only get sound thru the Analog iPod now connected to the CD input. So the Digital signal was not passing thru to Stereo/Direct/Pure Direct modes. I opened the top - clean - looks good if you look at like 1,000 transistors - all the 8A fuses up top, about 8or them were fine. OK. Went to the left and right panels - clean too - so it seems. Then I went underneath, bottom panel and viopla - found 2 fuses there on a Board - One glass 8A like the top and a ceramic 12A - both 125V. just to be sure I replaced the Ceramic with a 12A 250V new fuse and the glass 8A was fine as is and back to sqaure one - same issue. The I notices this board and the transformer (see pic with the model number 2336333009 and it has been soldered into the board and one one side there are three holes that looked like the solder fell off and I convinced myself it was this part that was causing the problem. not sure what it does. SO I decide to pull the board out and did successfully. Looking at it closeley you can see some brown burning type stain on several of the thingies. The biggest bruise is on a black chip like devise with a red amrker on it. I think this is bad and maybe some of the others or the massive transistor is not welde on right and possibly failed. When you hold the board up in the light it seems the holes are intentional since the holes do not lead to any "channels" on the green board. I am thinking the components have failed on this board and caused a cutoff to the DSP which looks clean. Can someone tell me what this transformer does. the power leads yell and white wires come straight from the power supply main plug and another three go to additional pwer supplies that you can plug to the back of the receiver. I paid $400 of this unit and I am thinking the board may cost another 200 or I just test and replace the transistor thingies. Not sure what to do since I am not an engineer. I'm an HR guy actually! Hee. Hee. I looked up the transformer part on Encompass - a Denon parts site and it's about 28 bucks but they don't have a pic of it. Any advice from pros out there will be much appreciated. Thanks.
