Peavey valve king 100 issue

[Tubetec]

I came across a problem with a Peavey valve king sometime back that I thought might be worth flagging up in here .
Theres a large wirewound resistor on the ht line ,green in colour, the wires that go to the standby switch pass very close to this .
One night a buddy of mine was up on stage playing away ,next thing fumes and smoke started billowing out of his amp , it arrived into my workshop for inspection and repair ,what had happened was the wires to the standby switch had come in contact with the hot resistor and melted ,almost caught fire by the looks of the damage afterwards .There was no major damage in the end ,wires too the standby needed to be replaced. If anyone gets one of these amps in its well worth adding a few extra cable ties and re-routing the wires  in such a way that contact with the resistor is impossible .

 

[iampoor1]

Thanks for the tip!

Also good to note, the main filter caps in this amp do not have discharge resistors. So make sure to discharge then unless you want a tingly sensation. 

 

[pstcho]

Hello there, anybody experienced with VK100 repair

i have one that worked perfetly forever till some weeks ago, power amp very low volume
if i plug something in the return to use only the power amp, it barely sound as loud as a 5W transistor amp

i replaced all the tubes preamp and power amp, but still same symptome, checked for cold solder, as well as general visual marks of burn or whatever weird, i find nothing

output transformer has correct impedance ( compared with somebody that had the values online ) not sure about what voltages to expect where though

any guidance wouldbe more than welcome

 

[NoisyIndividual]

Pull the output tubes and the phase splitter (pre-amp tube closest to the power tubes). Then measure the voltages on the pins (from the top of the chassis looking into the sockets) with everything switched on.
You should get something like:
Phase splitter:
Pin 1 hundreds of volts
Pin 6 hundreds of volts

Power tubes:
Pin 3 even more hundreds of volts
Pin 4 about the same hundreds of volts
Pin 5 -ve volts, around -40v/-50v or so


Do that and report back.



(This should be measured with the negative multimeter probe on the chassis, the positive touching the socket pins)

 

[CJ]

Effects loop is more like line level so a guitar plugged in will be weak.

Put a patch cord in the send/return jacks. Play guitar, if works then deoxit jacks.

If no worky, plug in guitar, get somebody to strum an E minor 7 chord while you check for ac voltages with volt meter.

Start at pwr tube grids pin 5 and work your way back to phase inverter grids pins 2 and 7.

Then preamp tube after tone stack pins 2 and 7.

Then vol control middle pin with knob on 10. Treble mid bass at 50 percent.

Next first preamp tube plates pins 1 and 6.

Finally input jack which should be 50 to 100 millivolts fluctuating.

Do not check plates on pwr tubes as a precaution

Check internal fuses if any.

Check speakers and cord.

Check guitar vol and jack. Or try different guitar if you have one.