Ampeg v-4-very low volume

[RANDY]

I have a ampeg v-4. The volume is very very low. All the controlls work but the vol is just super low. All the voltages are fine(plates, screens etc.) Any ideas on what could be the problem? Thanks.

[guitician]

Maybe the sockets/jacks need cleaning?

[RANDY]

I checked the pots/sockets and they are ok. When the power tubes are in, the bias voltage slowly drops. When I turn the standby on,the voltage returns to normal(-51). When I take the power tubes out, the bias voltage is normal.

[guitician]

I'm lookin at a V-4 schematic from '76 and the normal bias voltage is -28.5 volts. 545 volts on the plates and 338 volts on the screens. This is for 7027A/6550 tubes.

[guitician]

I'm lookin at a V-4 schematic from '76 and the normal bias voltage is -28.5 volts. 545 volts on the plates and 338 volts on the screens. This is for 7027A/6550 tubes.

I just found a 1970 schematic that -52 bias for 540v plates 527v screens, so it looks like yours is an earlier model. Those tubes could be drifting, what make are they?

[RANDY]

Thanks for the info. It turns out it just needs new power tubes. Thanks!