another punch 100 dsm issue

ben04srt · 9th February 2009, 12:20 AM

I replaced power supply fets and right channnel fets.
The amp powers up and plays ,no fets get hot but r17 gets really hot , can't figure out why.

Also the left channel is not as loud as the right, gains are down on both channels.

Perry Babin · 9th February 2009, 12:55 AM

If C9 isn't shorted and none of the FETs in the power supply are running hot, it's probably normal. They use a large resistor so it can dissipate the heat produced by normal operation. Unless it's getting hot enough to desolder itself, it should be OK.

For the gain problem, check the signal on pin 2 of both driver boards. I think both should have essentially no signal. If one does, the 10uf capacitor may be defective. Many of these caps leaked and caused damage to the board. To see it, you generally have to lift the capacitor.

ben04srt · 18th February 2009, 09:54 PM

I can't believe that the resistor gets that hot, but all the dsm's I have seem to do it.

I have a few leaking caps on this amp, I might as well replace them while I have it apart.

ben04srt · 21st February 2009, 01:35 PM

Changed out all the leaking caps and still not any louder on that channel.

ppia600 · 21st February 2009, 06:51 PM

So you changed the right channel fets and the left channel is the quiet one? Are you sure none of the left channel fets or drivers have an issue? If the left outputs are ok, I'd guess something on a driver board is the issue.

ben04srt · 21st February 2009, 07:49 PM

I have extra irf540's so I will replace them and see what happens.

Perry Babin · 21st February 2009, 10:16 PM

On pins 17 and 18 of the input board do you have the same signal level?

If you don't have a scope, use a test tone and measure the voltage with your meter (set to AC volts).

You stated that the gains were down in both channels. Do you mean the gain control is set to a low level or that there was insufficient gain (less than you'd expect) in both channels?

The 540s won't have any effect on the gain.

ben04srt · 24th February 2009, 01:05 AM

The gain controls are turned all the way down.

I checked pins 17 and 18 and got .563 or so on each pin, don't lknow if I am doing it right tho.

I also noticed that when u pull the rca cable out 1/2 way the is no change in volume like most amps.

Perry Babin · 24th February 2009, 03:10 AM

What about these (AC voltage - with the same input signal you were using before)?

Left channel audio driver board:
Pin 1:
Pin 2:

Right channel audio driver board:
Pin 1:
Pin 2:

ben04srt · 25th February 2009, 11:59 PM

Left channel audio driver board:
Pin 1: .363
Pin 2: .282

Right channel audio driver board:
Pin 1: .175
Pin 2:.265

input on pins 17 and 18 of input board are .532

9th February 2009, 12:20 AM	#1
ben04srt diyAudio Member Join Date: Jul 2006 Location: Dover,ohio	another punch 100 dsm issue I replaced power supply fets and right channnel fets. The amp powers up and plays ,no fets get hot but r17 gets really hot , can't figure out why. Also the left channel is not as loud as the right, gains are down on both channels.

9th February 2009, 12:55 AM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If C9 isn't shorted and none of the FETs in the power supply are running hot, it's probably normal. They use a large resistor so it can dissipate the heat produced by normal operation. Unless it's getting hot enough to desolder itself, it should be OK. For the gain problem, check the signal on pin 2 of both driver boards. I think both should have essentially no signal. If one does, the 10uf capacitor may be defective. Many of these caps leaked and caused damage to the board. To see it, you generally have to lift the capacitor. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

21st February 2009, 06:51 PM	#5
ppia600 diyAudio Member Join Date: Jun 2007 Location: Louis y ana	So you changed the right channel fets and the left channel is the quiet one? Are you sure none of the left channel fets or drivers have an issue? If the left outputs are ok, I'd guess something on a driver board is the issue. __________________ Don't worry... you can always turn the gain down!

21st February 2009, 10:16 PM	#7
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	On pins 17 and 18 of the input board do you have the same signal level? If you don't have a scope, use a test tone and measure the voltage with your meter (set to AC volts). You stated that the gains were down in both channels. Do you mean the gain control is set to a low level or that there was insufficient gain (less than you'd expect) in both channels? The 540s won't have any effect on the gain. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

24th February 2009, 03:10 AM	#9
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	What about these (AC voltage - with the same input signal you were using before)? Left channel audio driver board: Pin 1: Pin 2: Right channel audio driver board: Pin 1: Pin 2: __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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18th February 2009, 09:54 PM	#3
ben04srt diyAudio Member Join Date: Jul 2006 Location: Dover,ohio	I can't believe that the resistor gets that hot, but all the dsm's I have seem to do it. I have a few leaking caps on this amp, I might as well replace them while I have it apart.

21st February 2009, 01:35 PM	#4
ben04srt diyAudio Member Join Date: Jul 2006 Location: Dover,ohio	Changed out all the leaking caps and still not any louder on that channel.

21st February 2009, 07:49 PM	#6
ben04srt diyAudio Member Join Date: Jul 2006 Location: Dover,ohio	I have extra irf540's so I will replace them and see what happens.

24th February 2009, 01:05 AM	#8
ben04srt diyAudio Member Join Date: Jul 2006 Location: Dover,ohio	The gain controls are turned all the way down. I checked pins 17 and 18 and got .563 or so on each pin, don't lknow if I am doing it right tho. I also noticed that when u pull the rca cable out 1/2 way the is no change in volume like most amps.

25th February 2009, 11:59 PM	#10
ben04srt diyAudio Member Join Date: Jul 2006 Location: Dover,ohio	Left channel audio driver board: Pin 1: .363 Pin 2: .282 Right channel audio driver board: Pin 1: .175 Pin 2:.265 input on pins 17 and 18 of input board are .532

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