Peavey XR684F dead, help!

[Stratjeep]

Hi, I have a peavey XR684F come in the shop today, mostly I work on tube amps but the shop I do work for has just started carrying Peavey and want me to work on them.

The XR684F had a power amp output from another amp plugged into it's power amp in.

Fan starts, loud pop through speakers when you turn it on, but nothing else, no front panel lights or sound. I checked the fuses and the thermal fuses on the output heatsinks which all checked ok.

Any help greatly appreciated, have learned a lot from this forum, and greatly appreciate The free exchange of information.

David

[Enzo]

I hope you just stated that wrong. The ONLY thing a power amp output should even connect to is a SPEAKER. The POWER AMP IN should ONLY see line level signal, NOT the output of some other power amp.

If nothing lights up, then your low voltage power supplies are probably missing.

Get the schematics from Peavey qand start checking out the powr supply.

[Stratjeep]

I hope you just stated that wrong. The ONLY thing a power amp output should even connect to is a SPEAKER. The POWER AMP IN should ONLY see line level signal, NOT the output of some other power amp.

If nothing lights up, then your low voltage power supplies are probably missing.

Get the schematics from Peavey qand start checking out the powr supply.

Unfortionatly that's what the owner did Enzo, I have a schematic but it looks like it's only for the digital effects board, have to email peavey again. Thanks appreciate the reply!

David

[Stratjeep]

Hi Enzo, i have the right schematic now. At connector 1200 I don't have any positive 16 volts, and am going to replace q215 and perhaps the componets around it, I do get the voltage from the BR. This sound like the right path?

I have the power supply on the desk at the moment without the front panel connected. I thought you could use the heatsink for the BR as grind but soon found that gave erroneous readings, where would be the right ground point, I have been using jumper jp03.

Thanks!

David

[Enzo]

I don't have the schematic handy at the4 moment, but you do... so...

Look at the point they plugged into with the over hot signal. Peavey likes to protect things connected to the outside worl with pairs of clamping diodes to the +/-15v rails. Check all those for shorts. Then the IC that took that abyse at its input is suspect.

If an IC has a missing 15v rail, check the source power supply, if that is OK, then look for a burnt open isolatioin resistor or even a burnt open trace.

[Stratjeep]

Thanks, will do, I'll check in after I try these things.

Really appreciate the advice Enzo! I read a lot of your stuff, your an incredibly giving person.

David