Peavey max 115 ii 300 watt no sound.

[Bvbrain]

After a long time off it will give a low buzz then stop. So far I found and replaced a cap with a broken leg. Sparked when I tapped it. C 32. Also zener d 41 was shorted. Using a 22 v and 18 v instead of the 2 20 v zener 40 and 41. D5 has 0 voltage drop reading -50.8 on both sides. D4 reads 50.7 on r72 side and 39.3 at +High side.

In circuit d5 reads 0 ohms both directions. I still have to pull it to find if it is bad or if q6 tip107 is shorted.

2014 amp so I am using the 2012 schematic. Pic with readings before and after shorted d41 change.
MAX_115 PowerAmp_2012.pdf
Ideas?

[Bvbrain]

The new zener are 10% vs 5% I am waiting on the 20v 5% to arrive. I am hoping it is not up, the digital power amp.

Also, are there better aces to buy parts than Amazon?

[Bvbrain]

Just tested d5 out of circuit and it seems fine. It is looking more like q6.

[glebert]

Also, are there better aces to buy parts than Amazon?

Digikey and Mouser or others like that are "better" but I find ordering with them to be a hassle. Amazon and ebay are always right there with 1-click buying, cheap or free shipping, etc. Ebay there are tons of fake parts, I wouldn't be surprised if they were showing up on Amazon now too.

[Enzo]

I never buy components from Amazon or Ebay, I always use real suppliers like Mouser or Digikey.

All we see is the one power supply, which has your rails at 10v difference. +40 and -50 volts. Your issue is NO SOUND, not distorted sound. Even if your supplies are off like that, it wouldn't prevent the amp from making sound.

[Jon Snell]

Absolute maximum rail voltage is 42.5volts. 50volts will likely kill the TDA. Giving you two faults to look at.
Sort out the power supply voltages firstly then take a look at the TDA.

[Bvbrain]

Thanks everyone. The zener diodes came today. I put those in and removed Q6. TIP 107 pnp darlington. Collector to emitter are shorted, 0 ohms. Both directions. Base to anything is open both directions. Those will come in later in the week so that is my next step.

[Bvbrain]

Finished. Works again. Glad I did not have to solder on the trailer ic. Very small joints. Be sure to use the isolation plastic washers on the transistors or it will blow the fuse. 4 mp 5x20mm fast blow are hard to find local. I had to file ehe screw hole a bit to get the washer to work well on the replacement tip107 xistor.

[Bvbrain]

If it were not for boards like this one, I would have been stuck without a valid schematic. I hit a wall trying to get it from the maker. 2 vm and 2 email went without answer.

[glebert]

Good job getting it working. I have one of these amps and like it quite a bit.