Marshall tsl 602 problem

[Rod]

Hello Jon Snell!

With one probe of the multimeter on the amp chassis and the other probe on pin 5 of v2 it gives 4.78 volts, with proble on pin 9 of v2 it gives 4,78 volts.

[Rod]

Or you are telling me to put one probe on pin5 of v2 and the other probe on pin9 of v2?

[Helmholtz]

Or you are telling me to put one probe on pin5 of v2 and the other probe on pin9 of v2?

That's correct.

[Helmholtz]

Check between FILA and FILB, these can be easily measured between pins 5 and 9 of V2 NOT pins 4 and 5!

You're right. My bad.
Heater voltage is applied between pin 9 and connected pins 4 and 5, as it's 6V and not 12V.

Always happy if someone corrects my mistakes.
Sorry for confusion.

[Rod]

with one probe on pin5 of v2 and the other probe on pin9 of v2 theres 0 volts

I've got continuity between those pins.

[Helmholtz]

with one probe on pin5 of v2 and the other probe on pin9 of v2 theres 0 volts

Same with V3?

I've got continuity between those pins.

That would be the filament wire.

[Rod]

Yes in V3 with one probe on pin5 of v3 and the other probe on pin9 of v3 theres also 0 volts

[Helmholtz]

Yes in V3 with one probe on pin5 of v3 and the other probe on pin9 of v3 theres also 0 volts

So you def. need to check the bridge and its solder joints.

[Rod]

Helmholtz what voltage should i get if bridge were ok?

[Helmholtz]

Helmholtz what voltage should i get if bridge were ok?

As said, you should have around 6VDC between pin 9 and pin 5 (or4). Same voltage should be between FILA and FILB and between + and - terminals of the bridge.

[Rod]

Ok, im going to check it thanks

[Rod]

Just one more question, what is the minimum DC current and voltage for a ecc83 to light up? and to work properly

[g1]

It varies from tube to tube but I seem to recall people mentioning around 5V.

[Helmholtz]

Recommended datasheet values are 6.3V/0.3A, +/- 5%. This holds for rms AC as well as DC. Visible brightness varies.somewhat.
Tube will probably work at 5V, but performance (gain) and lifetime will be reduced.

[Jon Snell]

If you probe pin5 and pin 9 of V2 or V1, that will tell you instantly whether you have a good bridge or not.