# Pcx 4125 static jn one channel



## Alleycat (Sep 24, 2017)

I have a ppi pcx 4125 and have static distortion and intermittent crackling in the front right channel.I unplugged the rca and it does not change ,the amp has never been opened and I am wondering what to do and should I open it to inspect. Need it fixed it is getting on my nerves.


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## Alleycat (Sep 24, 2017)

I also hooked up another set of speakers and switched wiring around to see if problem followed the channel.it did then completely disconnected signal to it and it still persists


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## PPI_GUY (Dec 20, 2007)

Those older PCX and PC amps have a driver card inside that will go bad and create the exact problems you are describing. I'm not going to say it happens to every one of those amps but, it is a common problem. 

If the driver card is in fact the problem, you'll need to purchase a new one and find a tech ( I am not a tech) to swap it in. I would estimate the cost of a card (there was a seller on eBay who had a few) at around $75 and the labor cost to swap it out would be around $100-$150. So, probably $200-$225 plus shipping both ways if you can't find someone local. 

BTW, if you decide not to have that amp repaired and want to discussing selling it, let me know in a private message.


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## Alleycat (Sep 24, 2017)

I have investigated into the amp and am in process of finding the faulty board .I am testing boards and the resistors inside are reading 100 ohms each .2 per board ,8 in total. I took a magnifying glass to the large transistors on each board and notice broken solder joints on some of the feet .gonna attempt a repair myself with a little light heat soldering no flux due to the silver traces that are delicate to the heat and flux. I have to power it up and send a signal through my suspect channel and probe pin 3 on each board and probe posative speaker chanel and that will give me the board to that chanel


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## PPI_GUY (Dec 20, 2007)

Alleycat said:


> I have investigated into the amp and am in process of finding the faulty board .I am testing boards and the resistors inside are reading 100 ohms each .2 per board ,8 in total. I took a magnifying glass to the large transistors on each board and notice broken solder joints on some of the feet .gonna attempt a repair myself with a little light heat soldering no flux due to the silver traces that are delicate to the heat and flux. I have to power it up and send a signal through my suspect channel and probe pin 3 on each board and probe posative speaker chanel and that will give me the board to that chanel


Yup, the solder joints are the problem with those boards. Not sure I have ever heard of them being successfully repaired but, you may be able to do it. Please keep us updated on your progress!


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## Alleycat (Sep 24, 2017)

It took me a bit to get this amp working properly but I got help on diy audio and this site. I tore the amp apart and took a look inside ,no obvious signs of damage the amp is in pristine condition .know ING that these amps have issues with the output driver boards I began the investigate, out of everthing inside the amp construction wise the boards seem a little shady build wise ,poor solder joints and tarnishing on the back sides and just low quality looking all around ,ppi must have out sourced these boards j am assuming. .I did ohm test the resistors inside the board and they tested 100 ohms and within tolerances of anywere from 100 to 100.5 ohms .then with some help I was sent a macro photo of one of the small transistors on the board for comparison to mine .I had to get a magnifying glass to see the damage it was so microscopic. Here are some photos of basically what mine looked like .I was able to successfully repair by just using a half of pinhead of flux on each leg and quickly heating it up to re attach, the littlest amount of heat due to the heat sensation silver traces and pads, it worked perfectly believe it or not. Gonna keep an eye on it and still maybe replace the boards with aftermarket ones from the amp doctor,maybe instal footings so I can just Swap them in and out for any future reason instead of having to solder in and out .fun project to do .I would like to find another amp for cheap and repair myself some day . Thanks for the help ,I will keep in touch for future topics .


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## PPI_GUY (Dec 20, 2007)

Well done Alleycat! I had heard that those solder joints were susceptible to separation from the pcb, probably because of vibrations. Not an easy pix to be sure...tested your patience I'll bet.


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## JPOSEY (Nov 9, 2011)

I had two separate PCX-4125s have the same problem after 5+ years of use. Bad solder joints. RickyTricky repaired my last one. The first one was sent back to PPI and replaced with a Refurb. Very common problem.


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