Amplifier problems seem to be a common problem with these R129's. Has anybody opened one up, If so what is usually the problem with them. I have mine out of the 94 SL320, Just wondering what I should be looking for when I take it apart
Martin:I repaired many amplifiers in my time.
The sound will start to clip, and people may say it gets "sticky".. Basically half of the audio signal in sinusoidal wave is clipped, or the amp may shut down..The amp works for a while and the signal will just disappear..
You want to put in low leakage capacitors, and mail order your capacitors from Mouser Electronics in Texas or Digikey in Minnesota.. They must be fresh because that is the whole purpose. No ebay parts here. Voltage must be the same or larger..The replacement capacitance can be a little larger, but observe the lead spacing and physical dimensions.
The physical large capacitors are the problem 99% of the time. The semiconductor parts never blow up in the Mercedes Amps.
You can fix the amp for less than twenty bucks or so.
Remember with electrolytic caps that they can only be fitted one way. Each cap will have a series of negative symbols on one side. Usually the circuit board will show how the cap should be fitted with half of the area coloured black or with lines.I attempted this repair, but haven't been able to fix the amp. I was getting cracking/popping from the driver door speaker, as well as muddy base from the subwoofer. After desoldering and replacing the big caps with the recommended fresh ones from Mouser and reinstalling the amp, I now have no sound at all.
Is there a way that I can test pins on the amp with a multimeter to see if and where it failed? Is there anything else I should check? I have checked the fuse on the amp and it is OK.
Thanks in advance.
I've just repaired a power supply board to a smart battery charger. Not only were there blobs of glue between components, but the caps were actually stuck to the circuit board with a white adhesive!!To remove the "Hot glue" blobs I pinch and grab them with standard needle nose pliers, and at times use the ultimate tool of the flat blade screw driver to pry them out.
Most amps have them, but I have encountered a few amps not having the glue.