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Satyr 28th January 2013 08:08 PM

Punch45 Constant Noise from right channel-?
Hey all,
I decided to take the plunge and try to repair some of my old car amps (instead of just building speakers from time to time) as hobby projects.

I recently picked up a Punch 45 (HD), and after replacing the junk wire the PO had connected to it (with what looked like telephone crimping stuff) I got it to power on, but I have a high amount of static like crackling noise from the right channel. Initially, I thought it was due to the loose rca inputs- (and there may still be a problem with the inputs) but I tacked them back to their mounting surface (where they had become detatched) with a bit of solder and the noise continues.

I did alot of searching before posting, and found one old, dead, unresolved post where someone had a similar problem with an RF amp, and Perry had asked him to measure the resistance between the input rca shields/sleeves. I checked the resistance between the shields on this P45 and now that they're tacked down, they read 0.6 ohms between them.

So, what would be next?

I thought I would post this as a diy tutorial for others to follow who might be interested, and I will be reading on the bcae site as well. If there are any other sites that might help me repair a RF amp (or any other amps) I'd really appreciate the info. Thanks in advance and have a good week- John

Perry Babin 29th January 2013 01:40 AM

Is there any corrosion between the components on the board just behind the RCA jacks?

Satyr 30th January 2013 06:21 AM

Hi Perry, Thank you very much for responding. No, there isn't any corrosion- in fact, compared to many of the pictures I've seen of damaged amps, this one appears to be in pretty good shape. No burned spots, no broken traces, etc.

Perry Babin 30th January 2013 06:43 AM

If it's noisy. you'll have to trace the signal to see where the noise is getting into the system.

seankane 30th January 2013 07:13 AM

Look on the HBPIM board right behind the RCA jacks and look at the 2 10uf 16v aluminum capacitors and see if there is any brown spots around them.

dwvinky 30th January 2013 01:18 PM


Originally Posted by seankane (
Look on the HBPIM board right behind the RCA jacks and look at the 2 10uf 16v aluminum capacitors and see if there is any brown spots around them.

Ive purchased two 75hd's and a 45hd in the past month. All have ruptured caps on the PIM. Boards aint cheap either. Eventually when i quit buying broken amps, i'll order replacements. Lol. First thing im gonna do when i get new boards is replace the aluminum caps with low profile leaded radial caps. Ill just keep the leads short and heat shrink em.

Satyr 31st January 2013 04:36 PM

Hooked it back up to power and realized that the crackling, popping static noise was in both channels- and... whatever was failing, failed. Pop, smoke. Now it's dead...

I didn't have burned spots before, but I do now...

Satyr 31st January 2013 06:19 PM

Very bummed about this- my first project up in smoke (literally.) Would it be OK to try and post a picture of the burned spots for feedback/direction from y'all?

Perry Babin 31st January 2013 07:15 PM

Post the photos.

Were the transistors clamped to the heatsink when it failed?

Satyr 31st January 2013 10:54 PM<a hr...le_board_1.jpg[/IMG]

Hope this works. This is a macro of the whole board with purple arrows showing visble burns

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