Peavey CS800x problem - Smell it getting hot when powered on - HELP!

[CoopDaKill]

I was thinking, this was it (see pic). Big diode on bottom left. I circled it too. But it's marked 1N54??. Is this it?

EDIT: Sorry Jazz P Bass, I was posting about the same time as you. Thanks for describing CR105, now it's an easy find. I'm thinking the one blown 73180, will get back up and running. I'll call Peavey Monday.

[gtrmann]

I didn't realize the amp didn't work. Fix the amp first and look at the bias after. The output transistors Peavey uses are relabeled MJ15024 and MJ15025. You can get those at Mouser and Digikey last time I checked... Real cool experiment with a diode, clip one on a ohm meter in the diode check mode and put a iron on the lead ... Watch the reading change with the temperature rise ....the meter is reading the voltage drop across the diode in the diode check mode..

[CoopDaKill]

Thought I'd check some other components, while waiting on parts to arrive. Performimg diode test w/ DMM, on 1TB2 & 2TB2, test shorted. Are they both bad, or is this something that I've yet to learn about heat sensors? As always, Thanks!
Coop

[km6xz]

Thermal switches are normally closed type or normally open type. These are normally closed. There is one for the fan speed that is Normally open that is mounted on the heat sink between the two channels and one on power transistor of each channel a power amp board that are normally close. So these is normal to measure shorted. They will open when it too hot.

I am never a fan of randomly replacing parts, the cost aside, it introduces more points of failure such as bad solder joints, or mounting problems. Replace only those which you can prove are defective or not meeting spec.

[52 Bill]

The schematic is marked showing what kind of Thermal Breakers they are.

1TB2 is marked N.C. which stands for Normally Closed. It is a temperature controlled switch that is closed until it is heated to the trip point where it opens the contact. So if you get a continuity reading of zero ohms that is normal at room temperature.

The fan is also controlled by one of these, TB1 which is a normally open switch that closes when it reaches the trip point.

[CoopDaKill]

Good News, After replacing one 73180, both SAC187 (Triac's), and the four .33 ohm / 10watt resistors, that were getting super hot, the amp is stable and running fine. Interestingly, while reassembling the amp, I noticed a guide pin from a PL-2 transformer (on rear panel) had been broken off in it's socket. Same channel that had all the issues. If this PL=2 was broken while in operation, would that have been the killer? IDK? Very possible! Just wanted to give an update, and say Thank You to all, that took the time to help. I greatly appreciate you.

[Bootsy]

Just wanted to say I think it is awesome how much ee people look out for each other. Also I am just a little over 1 year to my associates for elec.eng. and I have managed to get a few spe hour connects and one has turned in to my first client for the electronics repair shop I am opening. He has tons of music amps and dj equip that he rents out and stacks of poorly maintained high quality goodies. Just so happens I am on my third amp repair and it is the cs800x. took me to long to distinguish the model version I wasn't feeling confident at all going into this but then I found this thread and I must say thank you to everyone that laid this repair out simple as ever. I am starting the testing on mine now .. visually the triac is bad and has actually scorched the pcb surrounding it. I also had the fan kicking on in tiny spurts. wasnt even sure where to start but the most obvious (burnt triac) and work my way through from there ... I dont want to barge in on another persons thread and just take over with my own issue but I dont normally post anything at all so not to familiar with the forum process aside from GoOgLe'N and Readin' them lol. Hope you dont mind coop if I join the discussion with my amp quandaries.
also .. I cant see attached photos .. there a setting for the forum site to toggle them or do I need to poke around in my browser/pc's settings to see if I can find the cause?

[Enzo]

Hi Bootsy, we'll help if we can. But please start a new thread for your amp. You are not butting in,this thread has been dead for over two years, but you will get better response with a fresh thread, plus there will be no confusion between your repair and the one in this thread. OK?

The output triac burns up when the amp channel goes to DC. The triac is a "crowbar" which shorts across the output when it detects DC. This usually blows the fuse/breaker, shsutting off the amp, and mainly it helps prevent your speakers from catching fire. It is a safety device. But like a car seat belt, it isn't necessary to the basic function of the amp, so remove the dead one, and we will replace it AFTER the amp is repaired.

We had a server crash that wiped out all the stored images a while back, and this thread is one of the victims. That is why you cannot open schematics or images from the thread. Normally you need nothing special to download them.

If you do not already have it, the schematic set can be had from customer service at Peavey for the asking, as with any of their schematics. If you have the CS800X, I am assuming it is the one with the large square vent grate in the front panel? Their schematic file should include teh parts layout and a parts list.

[Bootsy]

Thank you. Didn't even pay attention to the dates lol like I said I'm a noob in the forum world. I will go attempt to start one of my own. Thank you for being so quick to reply and assist