Amplifier had blown power supply - Fixed
I removed all Mur rectifiers and power supply works great.
When i installed the rectifiers I get a power supply pulse, like it's trying to start but shorts out and goes into protect then starts over every second.
It starts pulling .680 then pulls 10amp then .680 then 10amp and so on and LED goes green red green red.
I removed all output irf640n and still shorts with rectifiers in.
No shorts on output but on 10ohm gate resistors I read 20ohm.
Can anyone point me where/what I should be looking for.
I removed all Mur rectifiers and power supply works great.
When i installed the rectifiers I get a power supply pulse, like it's trying to start but shorts out and goes into protect then starts over every second.
It starts pulling .680 then pulls 10amp then .680 then 10amp and so on and LED goes green red green red.
I removed all output irf640n and still shorts with rectifiers in.
No shorts on output but on 10ohm gate resistors I read 20ohm.
Can anyone point me where/what I should be looking for.
Are you building any rail voltage with the rectifiers in the circuit?
If so, both positive and negative rail voltage?
What is the part number for the rectifiers?
Has anyone done any work to this amp since the last time it was working normally?
Do you have a 1 or 2 ohm current limiting resistor?
What's the current rating of your 12v power supply?
If so, both positive and negative rail voltage?
What is the part number for the rectifiers?
Has anyone done any work to this amp since the last time it was working normally?
Do you have a 1 or 2 ohm current limiting resistor?
What's the current rating of your 12v power supply?
positive rail = +198
negative rail = -199
MUR1620CT and MUR1620CTR
No one has worked on this amp as far as I know.
Yes to both 1 and 2 ohm current limiting resistor.
I have 3
1. 12v - 30v 10amp (This one)
2. 12v - 90v 100amp (custom built dell PS with 2 of these.)
3. 12v - 5amp (old radio shack)
I used the first one for testing because I can limit the current.
negative rail = -199
MUR1620CT and MUR1620CTR
No one has worked on this amp as far as I know.
Yes to both 1 and 2 ohm current limiting resistor.
I have 3
1. 12v - 30v 10amp (This one)
2. 12v - 90v 100amp (custom built dell PS with 2 of these.)
3. 12v - 5amp (old radio shack)
I used the first one for testing because I can limit the current.
Thats what it says look (here) maybe I missed something.
Before you answered I set my power supply to 1amp and pulsed it and built the rails and it came on but at 1amp.
Rails had +64 and -67. I'm not sure if
positive rail = +198
negative rail = -199
is correct, my probe keeps switching to 1x and not staying on 10x.
I wasn't sure if it was good to turn up.
Before you answered I set my power supply to 1amp and pulsed it and built the rails and it came on but at 1amp.
Rails had +64 and -67. I'm not sure if
positive rail = +198
negative rail = -199
is correct, my probe keeps switching to 1x and not staying on 10x.
I wasn't sure if it was good to turn up.
I don't use 90v for amps, that’s the only step up converter I can find that can handle that many amps.
The Dell power supply only has 12v. I wanted to test amplifiers at 13.8v so I use that step up converter.
My Oscilloscope has a switch on the probe that has 1X or 10X when I measured it the first time it was on 1X and read 198v, the second time I switch it to 10X because that’s where I set my Oscilloscope at.
I wasn't sure about turning the current up from 1amp.
Sorry if I got things screwed up. I'm still reading and learning.
The Dell power supply only has 12v. I wanted to test amplifiers at 13.8v so I use that step up converter.
My Oscilloscope has a switch on the probe that has 1X or 10X when I measured it the first time it was on 1X and read 198v, the second time I switch it to 10X because that’s where I set my Oscilloscope at.
I wasn't sure about turning the current up from 1amp.
Sorry if I got things screwed up. I'm still reading and learning.
Most servers can be modified to provide more voltage at rated current.
40 amps isn't enough to test large amplifiers. 250-300w maximum.
Current limiting supplies are the bane of my existence. A series resistor (especially with a buzzer across it) is better. No one will use them.
No matter what you use, you look at the gate waveforms to confirm that they're acceptable and note the heating of the PS FETs. Then go to direct (unlimited) power (except a 10-15 amp ATC/ATO fuse). If the current draw immediately goes really high (analog meters on amp meter better), and stays there for more than a second, switch the power off.
To protect the FETs, clamp them to the heatsink. It takes less time to do that that struggling for an hour wondering if things are OK. With a 15 amp fuse in the power line and the FETs clamped, there is essentially no risk of damaging large FET banks (or even single FET banks) from high current draw.
40 amps isn't enough to test large amplifiers. 250-300w maximum.
Current limiting supplies are the bane of my existence. A series resistor (especially with a buzzer across it) is better. No one will use them.
No matter what you use, you look at the gate waveforms to confirm that they're acceptable and note the heating of the PS FETs. Then go to direct (unlimited) power (except a 10-15 amp ATC/ATO fuse). If the current draw immediately goes really high (analog meters on amp meter better), and stays there for more than a second, switch the power off.
To protect the FETs, clamp them to the heatsink. It takes less time to do that that struggling for an hour wondering if things are OK. With a 15 amp fuse in the power line and the FETs clamped, there is essentially no risk of damaging large FET banks (or even single FET banks) from high current draw.
I looked everywhere to find how to adjust the voltage for Dell power supply but with no luck. I did take one apart to see if I could see a adjustable resistor but these had none. I'm not smart enough to wire in a adjustable resister or what needs to be done.
I did have to wire 2 of them together to get 24v for my motion sim motors.
"40 amps isn't enough to test large amplifiers. 250-300w maximum"
I wire 2 of them in parallel to get 80amps, plus use high output fans to keep them cool to push them hard. (no problems yet)
I think I read that in your book where you took a flat aluminum bar and clamped it with small binder clip.
I do use the OCP on my power supply that protects most bad things from happening.
I tried to pulse it with 5amp with no luck.
Why would it work with 1amp?
.
I did have to wire 2 of them together to get 24v for my motion sim motors.
"40 amps isn't enough to test large amplifiers. 250-300w maximum"
I wire 2 of them in parallel to get 80amps, plus use high output fans to keep them cool to push them hard. (no problems yet)
I think I read that in your book where you took a flat aluminum bar and clamped it with small binder clip.
I do use the OCP on my power supply that protects most bad things from happening.
I tried to pulse it with 5amp with no luck.
Why would it work with 1amp?
.
What power supply controller IC is the dell using?
Does this dell supply have external connections to let it monitor the voltage off of the supply? It's like the sense wire on an alternator that monitors the voltage at the fuse box instead of at the alternator's output terminal.
It's good to test at higher voltage but when run hard, large amplifiers will draw the voltage down in a car. I don't know how hard you test. I tested class D amplifiers for 3 hours so large supplies were required. For shorter terms, a battery is a good option.
Yes, temporary heatsinks on 1" x 3/8" aluminum stock. This is for short term testing but will help protect FETs from short bursts of current. This is TT9, item #3.
FETs don't instantly fail when they pass high current. Temperature is the enemy and they have to get really hot while passing significant current to fail.
Does this dell supply have external connections to let it monitor the voltage off of the supply? It's like the sense wire on an alternator that monitors the voltage at the fuse box instead of at the alternator's output terminal.
It's good to test at higher voltage but when run hard, large amplifiers will draw the voltage down in a car. I don't know how hard you test. I tested class D amplifiers for 3 hours so large supplies were required. For shorter terms, a battery is a good option.
Yes, temporary heatsinks on 1" x 3/8" aluminum stock. This is for short term testing but will help protect FETs from short bursts of current. This is TT9, item #3.
FETs don't instantly fail when they pass high current. Temperature is the enemy and they have to get really hot while passing significant current to fail.
I really don't know anything about these power supplies but I just took the cover off so you can see. (first picture)
On this DS18 I double checked for shorts but can't find any.
I checked all diodes and resistors and all look good except the 10ohm gates measure at 20ohms.
The only thing I haven't done was the vertical add on card. I took a picture the best I can without removing it.
On this DS18 I double checked for shorts but can't find any.
I checked all diodes and resistors and all look good except the 10ohm gates measure at 20ohms.
The only thing I haven't done was the vertical add on card. I took a picture the best I can without removing it.
Use a supply that will not limit the maximum current if there is a short circuit with the limiting resistor. 15 amps for the 1 ohm resistor. about 10 amps for a 2 ohm resistor.
The resistor needs to be at least 50w. 100w or greater is better. Use dummy loads if you have them.
Watch the heating of the FETs as the amp tries to power up. If it draws more than about 5 amps for more than a few seconds, remove power.
The resistor needs to be at least 50w. 100w or greater is better. Use dummy loads if you have them.
Watch the heating of the FETs as the amp tries to power up. If it draws more than about 5 amps for more than a few seconds, remove power.