fender deluxe reverb 65 repair

[Helmholtz]

Why do you have a cathode voltage? Did you add cathode resistors?
In post #27 you reported equal grid voltages of -35V. The new OT shouldn't change that.
What are the resistances of the OT primary halves?
Do you have OT specs?

[tepsamps]

Yes i added cathode resistors, 1 ohm. The primary is about just less than 200 ohms per side.
I know that OT does not change grid voltage, but maybe i took the voltage at the wipper of bias pot.
But about G2 voltage? It's strange, no? I'm gonna check the wires...

https://www.hammfg.com/files/parts/pdf/1760H.pdf

[Helmholtz]

Screen voltage at idle often is like a couple of volts higher than plate voltage.
With signal average plate voltage is typically much lower than screen voltage anyway.
Sometimes mains voltage fluctuates by a few percent between measurements making supply voltages change by the same percentage.
Maybe repeat measurements.

[tepsamps]

Thanks Helmholtz.
I changed the 220 K resistors (grid leak) for the bias, and now ir's ok about voltages and i have about 20 mV at both cathode for -40 v of grid voltage (taken at the pin). Quite hot...

But i'm a little concerned about the noise, the static noise i mean. It's quite loud but i'm not used to amps without master volume and it's certainly normal.

When some speak about a re-cap job on old amplifiers, they mean coupling cap and cathode bypass cap? All the caps?

[Helmholtz]

20mA idle current is good. Means around 66% PD - not too hot.

[g1]

When some speak about a re-cap job on old amplifiers, they mean coupling cap and cathode bypass cap? All the caps?

Usually they mean the electrolytics (filter,cathode bypass, bias), not coupling caps unless they are found to be leaky.

[tepsamps]

OK, thanks...

Now i have another issue, the tremolo does not work anymore. It seems that there is no tube inside the socket, almost 0 V at V5a K and 3 V at V5b K. And the voltage does not drop across the plate resistor.

I checked the tube, it's good in another amp. I put another tube, and before i have put contact spray in the noval socket, but it's the same. I have had already this kind of issue in one of my amps, and it was the socket.

I guess it's belton on the DR, and i have already had issues with belton noval sockets, exactly this.

This amp is cursed...

[Tom Phillips]

OK,...Now i have another issue, the tremolo does not work anymore. It seems that there is no tube inside the socket, almost 0 V at V5a K and 3 V at V5b K. And the voltage does not drop across the plate resistor....

I suggest that you investigate the V5A cathode circuit. With the V5 tube removed and the amp off & unplugged, take a resistance reading from V5A pin three probing from the top of the tube socket to chassis ground. Tell us the reading you get. It should be the value of the cathode resistor. If not, then you can start narrowing the test points to determine if it's a bad resistor or a bad connection.

[tepsamps]

I find 2.7 K at pin 3 and 100 k at pin 8, so it's ok. Now from D to pin 1?

I checked also and it's ok, 230 k and 6 M at pin 6.

But this tube is very easy to remove, maybe the contacts are loose. I don't know actually...

[Tom Phillips]

[QUOTE=tepsamps;n1005711.. Now from D to pin 1?...[/QUOTE] I'm not sure what you mean by that.
With the tube installed can you see that both heaters are glowing?
I ask because I have found bad solder contacts at the heater connections to the tube socket that would turn off one heater. Sometimes they are really hard to see until you take a really close look. It is possible for a heater fault to turn off just one of the two triodes inside a 12AX7.