Beiträge von depimp

Hello,

I can´t post any photographs now but here comes the voltages:

outlet wall: 240-244 V.

Trafo outputs: 307 and 16 V (should be 272 and 14 )

DC outputs: 406 and 12,4V ( should be 365 and 12.7)

Tube plates without tubes: 1A: 388, 1B: 391, 2A: 368, 2B: 406 V (should be 365 all of them).

I know its dangerous to use a higher value fuse but it is the only way I have to do the measures.
I think the problem is the sum of high voltage at the outlet and a transformer in the limit of tolerance. As a result , the DC voltage is out of the 10% acceptable (but the heaters voltage is ok, perhaps by the regulator.

I don't understand either why all the tube plate voltages are different quantities without tubes. It means that there is some current in the circuit, doesn't it? So...

Please, reply soon because I can't help without you. Thank you very much

I´ve just assembled the bass preamp kit and the measures are all wrong:

The trafo output is about 15% high, so the plate dcV is also high (the heaters V. is ok).

Without tubes, the plate voltages are high and different from one to another, as if there was some current.

With tubes, all voltages are high, some cathode voltage is twice the correct quantity.

The fuses have blown and now the preamp is working with an oversized one.

Can I reduce the plate voltage by adding some resistance in the power supply?

Please, help me because I don´t know what to do at all.

Thanks a lot
quantity.