1967 Farfisa TR-60

[manolo]

Hello!
Low volume , no reverb,mystery transistors (SGSIW9640)
It need new speakers and new electrolytics
Here is the schematic and some pictures

TR60-CENTRAL.pdf
TR 60-1.pdf
TR 60-2.pdf


••••••

[manolo]

i change all electrolytics and now the volume is high but i hear noise(frying eggs) from the speakers even if the volume pot is zero.
No bias pot ....
I have a problem with the reverb tank
Here


One coil is off and the other is 148 ohms
Any suggestions please?

[nickb]

Looks like you are missing some springs and the coil is damaged. Hard to tell but I'm guess not repairable. To figure out a replacement are there any numbers marked on the tank? This will help:Spring Reverb Tanks Explained and Compared | Amplified Parts

Popcorn noise is often a bad transistor. Next choice, bad ceramic capacitor. Spray suspect components one at a time with a little freezer spray.

Interesting find though - thanks for sharing the pics. Now, all you need is one of those transistorized accordions to go with it

[52 Bill]

The noise can be caused by a bad transistor or even a bad resistor. Try and isolate the source by turning down all of the controls and see if any one of them changes the sound of the noise.

The tank needs to be replaced. Based on the schematic, a tank like the one used in a Fender tube amp should be the correct replacement type.

[J M Fahey]

Agree.
Work backwards lifting one couplilng cap leg, stage by stage, until you lift one and noise does not stop, then it comes from the next up in the chain.

And ,,, no bias pot there ...

[manolo]

Thanks all!
I took a reverb tank from a Farfisa FR-40 and ...only channel 1 has reverb not channel 2.I cant figure out if ch2 have reverb from the schematic.
Tried the freezer trick but no difference so maybe the 3 2N3055...
Still searching..
I wonder if this amp is a copy from a solid state Vox or something else....
Thanks again

[52 Bill]

The reverb is only connected to channel 1.

The power amp is sorta like a Thomas Organ Vox amp, with the tranformer driven output stage.

[nickb]

Only ch1 has reverb by the looks of it. If the freezer spray didn't do the trick, then you'll have work backwards as Bill & Juan described above to find the source of the noise.