Tube Amp Archive

Should there be an union between these two points? Where the red line is.

So, main ssues you're talking about are :
1. Plate voltage 485v when power tubes can handle 400v at maximum.
2. Green wires from lamp 5.4v instead of 6.4v.

????

I want to tell this to the builder. Then, if he can't fix it, i'll call the only good technician ( so far from home and very expensive. )

I don't know if caps could be part of the problem or not. Anyway i'm gonna remove all 715's and i'll try tad mustard, Mallory, Sozo,.. but i don't know about smaller ones like treble tone stack 250pF cap. Suggestions are welcome

OK the pcb mystery is cleared up now. 5.9V seems a little bit low but is within 10% of 6.3, so should affect tube operation. It's best to measure at the actual terminals that the wires from the power transformer connect to; that's usually the front panel lamp. It would also be useful to measure it ...

I've just tested green wires again with new tester cables. Same results, 2.7v each. Could be the fan ? Try putting one probe on to terminals 4-5 of V6, the other probe on to terminal 9 of V6. Or across the 2 resistors at V4. Expecting about 6.3Vac from one green wire to the other. Be careful that t...

Builder's answering about the mini pcb circuit :
"Yes, that's just a circuit of very low power that I made, it transforms the 6.3 volts AC of the filaments into 9 or 12 volts DC, to power the fan, nothing that affects the sound"

The pcb looks very odd. I asked the builder by mail.

Fan is 12v . One red and one black wires come from the fan and then they go to the fan switch and pcb circuit along with a yellow wire coming out from the switch.

Ups!! Now i hope it's correct

Thanks, now i'm going to do all that. The pcb looks like it is for the fan

Thanks but the problem was already before trem mod. As i think i said before, my two last super reverb style amps had same mods as this one. I mean: trem mod,disconnected normal channel switch, rectifier switch , nfb,.. except the fan and the vibrato channel brigth switch ( 2 modes of punch )

Are you sure that the red wire to terminal 3 isn't actually red/orange? It's just that you've already got 2 red wires from your PT going to the silicon diode tagstrip. Sorry, the pin 3 red wire has a very small orange line i didn't see last night. I've just tested green wires again with new tester ...

I did this. I'm gonna leave now but this evening i will have look at layout

3 Is there a note on the back of the amp advising what the mains wall outlet voltage supply it should be connected to, eg 220Vac, 230Vac etc? Or a supply rating plate, eg 230Vac 2 Amps 460 watts or VA? All mains powered equipment should have that info permanently affixed, along with the intended ma...

Bass 2 Mid 8 Treble 0 Those are unusual settings. I suspect something is not wired correctly or wrong value pots. Do you use these settings for both Normal and Vibrato channels? I've never played in my life with treble at zero. This is the first time. It's the only way to avoid that ugly crunch whe...

pdf64 wrote: ↑Fri Aug 24, 2018 9:17 am 2 The Vac from the PT to the heater circuit might be measured at the green wires connected to the front panel pilot lamp terminals.

2.7v each green wire