peavey vypyr 15 smoke

[s1ms]

Hi guys,

just bought a used Vypyr 15 plugged it played with it for 20 minutes and smoke. I live in UK and the model is a UK model so no problems with mains voltage. The amp board looked fine I did not see any burned parts but it smells bad. When I power it up now it just buzzes and no lights are on. Where do I start to look for problems? Would someone be willing to guide me with the repair process? I know how to solder and I know a difference between a capacitor, fuse and other parts.

I have the schematics and a multimeter.

If I manage to fix it I will learn to play the electric guitar! I promisse!

Thanks!

[Jazz P Bass]

Can you post the schematic?

[s1ms]

Can you post the schematic?

http://music-electronics-forum.com/t12851/

[Jazz P Bass]

What I would recommend is that you narrow things down to the power supply.
Disconnect all of the ribbon cables to isolate just the power supply board.
You can check the power supply with the power off.
Go from V+ & then V- to ground. It should not read short.
Check the regulator input & output pins to ground. Again, no shorts.
The diodes on the 5 volt regulator & the regulator itself should be checked.
If nothing appears abnormal, power up the unit.
You should be able to test the + & - 30 volts & the two 12 volt regulators, along with the 5 volt regulator.
The +12 volt regulator, from left to right, looking at the front, is input, ground, output.
The -12 volt regulator is different. Left to right will read ground, input, output.
The 5 volt is the same pinout as the +12.
If everything looks good, turn off the unit & plug in the DSP cable.
Check the voltages again. If everything remains good, check the regulator on the DSP card. 3.3 volts.
If that is good, power down & install the input jack cable.
Power on the unit.
At this point you should see the LED's doing there dance.

[s1ms]

hi,

the first regulator U1 7805F that makes from +8V to +5V seems to be ok. When powered up it showed +11V (not too high?) and +5V.
I did not power up the other Regulators (with P14, P15, P16) as the negative regulator U3 7912F has a short between GND and Vin (first and second pin).

[Jazz P Bass]

That may be the issue.
LM7912 will do as a replacement.

[s1ms]

That may be the issue.
LM7912 will do as a replacement.

I will replace it with a new one tonight but I wonder what was the source of the failure? I hope it wasn't the main board.

EDIT:

after removing all 4 diodes from the +-18V part I found two diodes dead. I also removed the regulator but it seems to be fine, though the first and second contact points are indicating a short.

[s1ms]

Problem solved! Faulty TDA2040 power amp. Replaced with TDA2050. Amp works!

Thanks guys for the tips!