VoxAC30 CC phase inverter problem?

[cigskillu]

I am working on a Vox AC30 CC (Chinese) it has low volume and less tone. Im shooting for possibly the phase inverter as a problem. On the schematic is says there should be 42volts on the grids of the phase inverter, my live readings show only 20 volts. The Anode's are 228v and the cathode's around 50v so there fine. All the voltages on all the other tubes are fine. Do any you have any voltage readings from another similar phase inverter? or ideas?

-Will

[Alex/Tubewonder]

When you measure voltage between grid and ground the meter is drawing a small amount of current that is enough to pull grid voltage down.

Even the 42V given on the schematic is useless information without any information on what the meters internal resistance is.

With 61V on cathodes (on schematic) and 42V on grids both PI triodes would be in total cut-off.

Measure the voltage across the phase inverters common 1.2k cathode resistor (R26), it should be around 1.5V. Together with correct voltages on anodes it will indicate that PI tube is just fine.

[cigskillu]

thanks

it turns out his amp was fine, he just blew his speakers. And i just didnt know how loud an ac30 was untill he listened to it and said it was fine.