I've got a Punch 40 DSM I am starting on. It has leaking electrolytic capacitors on the main board as well as the input/pre-amp board (2nd image). I will replace all of the smd electrolytic caps. I guess I also need to remove both LM833s to clean the electrolyte residue from under them. Is that correct?
But first I have a question about the P.S. driver board. I am trying to find out if I am missing parts or if some 40 dsm's did not have a LM393.
I have found one pic from a thread by @Dr Zeus https://www.diyaudio.com/community/threads/rockford-punch-40-dsm.371046/ that is missing the exact same parts I am missing other than he also was missing the LM339D which I have on mine.
All other photos I have found of the PS driver board show it fully populated. What gives?
Currently the gate drive on the PS FETs looks good and I have +/- 21 Vdc for the rails and +/- 12 Vdc for the secondary supply.
But first I have a question about the P.S. driver board. I am trying to find out if I am missing parts or if some 40 dsm's did not have a LM393.
I have found one pic from a thread by @Dr Zeus https://www.diyaudio.com/community/threads/rockford-punch-40-dsm.371046/ that is missing the exact same parts I am missing other than he also was missing the LM339D which I have on mine.
All other photos I have found of the PS driver board show it fully populated. What gives?
Currently the gate drive on the PS FETs looks good and I have +/- 21 Vdc for the rails and +/- 12 Vdc for the secondary supply.
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From what I see, the 393 is used for additional thermistors on the larger amps. The 40 has only one thermistor.
Look at the solder on the empty pads. It's so consistent that it has to have been applied by machine.
Yes, remove the 833s and clean under them. You need to remove 100% of the electrolyte.
Look at the solder on the empty pads. It's so consistent that it has to have been applied by machine.
Yes, remove the 833s and clean under them. You need to remove 100% of the electrolyte.
I'm going to start removing the caps and cleaning the input board.
I really didn't want to remove the board if at all possible, so that I don't potentially cause any more problems. I can remove the rca jacks to give me access to the ics and the top row of caps, but the negative side of the bottom two caps are so close to the main pcb I don't see how I can get a soldering iron to the pads.
Is there a trick for removing these without taking the input board out?
Thanks.
I really didn't want to remove the board if at all possible, so that I don't potentially cause any more problems. I can remove the rca jacks to give me access to the ics and the top row of caps, but the negative side of the bottom two caps are so close to the main pcb I don't see how I can get a soldering iron to the pads.
Is there a trick for removing these without taking the input board out?
Thanks.
Also what is the difference in the green and black resistors?
While searching for the answer I found a lot of speculation as to 'high precision', temp coefficient marking,...etc. but no definitive answer.
While searching for the answer I found a lot of speculation as to 'high precision', temp coefficient marking,...etc. but no definitive answer.
I never tried changing parts (except one SMD resistor that commonly overheated on the output driver board) without removing the boards. Added solder, a good desoldering pump, flux and braid (all things that you likely use daily) takes them off with no damage. You have to be careful. Don't actually apply pressure to the pads with the iron. Just heat the solder as is shown on the TT5 page, item 16.
Standing the amp up on end may make it easier to do if you decide not to remove the board.
Standing the amp up on end may make it easier to do if you decide not to remove the board.
Anybody have guess at the question in post #4?
Anything special about the green colored resistors?
I have found some that need to be replaced and wondered what is the difference, if any. I have not been able to find any definitive answers by searching.
Anything special about the green colored resistors?
I have found some that need to be replaced and wondered what is the difference, if any. I have not been able to find any definitive answers by searching.
I took all the smd electrolytics, 10uF 16V, off the main pcb and input module. Almost every one has leaked electrolyte on the board. Two pads lifted and one of the two separated completely from the trace.
My question is concerning C16. On my board when comparing to the silk screen and the schematic it is on the board backwards. I have found photos of different 40 dsm's some with it like the schematic and mine and another one with it turned around. How should I install the new one?
What damage could occur if it is not installed properly?
C16 goes to pin 9 , 10 and 14 on the power supply module.
My question is concerning C16. On my board when comparing to the silk screen and the schematic it is on the board backwards. I have found photos of different 40 dsm's some with it like the schematic and mine and another one with it turned around. How should I install the new one?
What damage could occur if it is not installed properly?
C16 goes to pin 9 , 10 and 14 on the power supply module.
I should also mention, that capacitor on my board was slightly different than the originals, so it had been changed before.
Also, the pics of the boards with C16 matching the orientation of the schematic had the 393 on the PS module.
The pics of the boards that had it turned around the other way, like mine, did not have the 393 installed. Not sure if any of that matters.
Also, the pics of the boards with C16 matching the orientation of the schematic had the 393 on the PS module.
The pics of the boards that had it turned around the other way, like mine, did not have the 393 installed. Not sure if any of that matters.
Measure the DC voltage on both pads of C16. With remote applied, one terminal should be much higher than the other.
Which is higher?
Which is higher?
Just to clarify, all of the small 10uF 16V caps are out of the circuit. Is it safe to power up without these installed?
The pad the positive side of the cap was hooked up to reads 4.95 V and were the neg. hooked to is 1.4 mV. I guess it was oriented "correctly" in this amplifier.
Oddly enough it doesn't match the silk screen.
Oddly enough it doesn't match the silk screen.
Looking at the 60, 100 and 200DSM diagrams, all have the positive terminal of that cap connected to pin 9 instead of pin 14.
I can't find the 60 dsm schematic, is it in the Rockford folder?
I guess there was a change somewhere on the 40s.
Mine and the one I found like it are both marked Rev B dated 02/10/93.
The one I found that matches the 40 DSM schematic was dated 02/04/93. I could not see the revision code.
I think it has something to do with the 393 on the PS module being there or not.
I guess there was a change somewhere on the 40s.
Mine and the one I found like it are both marked Rev B dated 02/10/93.
The one I found that matches the 40 DSM schematic was dated 02/04/93. I could not see the revision code.
I think it has something to do with the 393 on the PS module being there or not.
The 393 is only for amps with more than 1 thermistor (larger than the 40).
The 200DSM diagram is in that folder.
The 200DSM diagram is in that folder.
What's strange is the 40 dsm schematic (PS Module wp-0039) shows the 393 and the pictures of the 40 dsm's that match the schematic have the 393 installed.
If you get a chance go to Amp-performance and look at the pics of the 40 dsm. https://www.amp-performance.de/en/772-Rockford-Fosgate-Punch-40DSM.html
It matches the schematic (orientation of C16) and shows the 393 installed. I couldn't get the pics to upload here, I guess a copywrite issue.
Maybe they realized early the 393 was not necessary on the smaller amp (1-thermistor) and removed it and its accompanying components to save some money?
Edit: After looking more closely the earlier 40 dsm in the pics at the link above had a 2nd thermistor. They must have realized they only needed one and that was the reason for the change?
If you get a chance go to Amp-performance and look at the pics of the 40 dsm. https://www.amp-performance.de/en/772-Rockford-Fosgate-Punch-40DSM.html
It matches the schematic (orientation of C16) and shows the 393 installed. I couldn't get the pics to upload here, I guess a copywrite issue.
Maybe they realized early the 393 was not necessary on the smaller amp (1-thermistor) and removed it and its accompanying components to save some money?
Edit: After looking more closely the earlier 40 dsm in the pics at the link above had a 2nd thermistor. They must have realized they only needed one and that was the reason for the change?