Peavey PV2600 problem

[blindboybenton]

Hi all

I have problem with a PV2600 and i caused it
peavey_pv-2600.pdf

came in for a funny noise from Channel B.. I sorted that by some resoldering. tested it all working, when i screwed it up i didnt see that i had cabled tied the voltage supply cables to channel A a little close to the heatsink. When i screwed the cover on i had pinched the orange cable (LRVB2) 57v+ and it cut into the heatsink

Turned the unit on and a bang. I repaired the cable check and turn on again tripping the safety. On investigation found one of the 2sa1943 s/c and one of the RFZ44 s/c on channel A
nothing else had gone. I replaced and turned on, without a lamp limiter ( broken ) same thing again

so i checked everything this time and too be sure i replaced every semiconductor on the heatsink. inc 2sc4793 and 2sa1837
Checked all resistors found nothing open Checked all diodes all seems ok. There are no s/c across the outputs for speakers
Have check all semi's on channel B all ok no shorts

With both boards in and connected turn on the lamp limiter ( 100watt bulb) pulses then it settles down with both DDT led's lite up and the green power led's pulsing
Lamp limiter is staying dimm and not pulsing sometimes the signal led will come on for channel B

Advice on anything i can check before i plug into the mains supply

BBB

[blindboybenton]

What i forgot too put was

This is the first PV2600 ive had in the workshop. Do they like the lamp limiter, i know some amps do and some dont

[Jazz P Bass]

That schematic link is dead.

If you have the file, please compress it to a zip file & reload it.

[blindboybenton]

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bbb

[Jazz P Bass]

Not sure what happened to the amp.

You would think the 57 volt rail to ground would simply affect that rail.

Start at the beginning.
Test the power supply voltages.
Vdc & Vac.

[blindboybenton]

Yes i was surprised it took out some output transistors.

[J M Fahey]

Sadly that's a beast of an amp, very complex, quad rails, hairy deadly voltages, you name it.

That said, I see many damage ways out of that +57V rail shorting.

1) you might have killed Q121 and its drivers and/or CR127

2) if DC appeared at the output, that would have triggered CR128 .
They sometimes suicide to protect the speaker , sometimes even nuke some output transistors besides the original failed ones.

I guess Peavey would much prefer sending user a new amp and a couple bottles Champagne rather than facing an angry soundman in court because of DC blown speakers.

3) this amp looks like it will stand a lamp limiter, no speaker connected of course, it's not SMPS based but good old iron transformer

4) you'll have to play very carefully with this one, go very slow.

Start by measuring all power transistors, including rail switching MosFets, their drivers, diodes, with the diode test function.
If any tests short, only then you pull it to check it outside.

You may compare measurements with same part other channel, that's of some help.

Good luck.

[blindboybenton]

Hi Jm

On the second time on the amp i removed all the semi on the heatsink Q105-115 + CR134-CR127 diodes. some were blown others were ok. so i decided as my supplier only sold some in packs of 5 to replaced all for new. Channel b is ok nothing blown on that side. Thanks for the info on if the amp will work on a limiter.

[Jazz P Bass]

Peavey 2600 Schematic

For those of you following along at home, here is the schematic.
The link in Post #1 is dead.