who is the amp guru

Oh I see.

Channel one isn't meant to have reverb and tremolo, so it's working as it should be?
Channel two should have reverb and tremolo, but you're only able to trace a signal as far as the tank and no further?

Makes sense to pull the tank out and check it then. :)

I've no idea what size a quarter is, btw. :p
 
that still leaves me with the no tremolo problem to deal with in the meantime. I will have to take a look at some tremolo circuits and do the test with the analog meter I have. I am not sure what I am seeing on the scope. It may be to slow for it?
 
The best way I've found to 'see' a tremolo circuit in action is with a plain old-school analog voltmeter or even a VTVM, like so;

VTVM.gif​

As the 'Speed' control is set higher, the needle should swing faster. Assuming the wiring is right (even if you check all capacitors and resistors for value, remember the wires connecting them together!), and the tube is good, all the can be done is now test the capacitors for leakage. Few people have a leakage tester, and your typical Fluke DVM can't check leakage, so just changing all three oscillator capacitors is usually fast and pretty much guaranteed to solve the problem. Well, as long as the footswitch part is right.
 
First of all I have to say thanx to all who have helped. I haven't got to the trem circuit yet but the reverb tank is shot. The real fine wires in it are broken so I will have to do something about replacing it. Obviously I am not going to find the same one.
 
I am having fun doing this more than anything else. But if I do fix this it may be the last one on the planet? No one I know has ever seen another one and I know quite a few old musicians. Then I have my masco amp to work on. I replaced the filter caps and some other parts but I am not quite there yet. I only have the amp, it is shown with a preamp. The amp is a dual rectifier with 2 6L6s rated at twenty watts rms. I also fixed the bias circuit on one of the 6L6s and now I have distortion in the preamp circuit. It is getting twice as much voltage to the plate than what is stated on the schematic so next I will check its plate resistor. The gain pot is shot and I bought one off of ebay, supposedly brand new but it was no good.
 

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I bought all new caps and pots. Have a nice clean signal coming through both channels. Bought a reverb tank and hooked it up. When I bang it I can hear the verb and the depth pot is working but I get no reverb on the guitar signal. My AF generator just went on the fritz and I am waiting for new tubes for that to come. I am not sure about impedance on the reverb unit? What effect will that have if it is not matching?
 
How is the reverb introduced? Is there a mix knob or is it just switched in at a fixed amount?
What your describing suggests that the tank output is fine, but there's no channel input getting to it, right?

I can't remember the full story (going out now- sorry), but did the verb ever work?
Is there any chance someones hard wired a bypass or something?
 
I don't know if the verb ever worked. The existing reverb tank is scrap. When I get the AF generator going again I will take a look see.
There is a reverb volume control that seems to reintroduce the signal through the volume and tone control network.
 
dragonworks said:
I don't know if the verb ever worked. The existing reverb tank is scrap. When I get the AF generator going again I will take a look see.
There is a reverb volume control that seems to reintroduce the signal through the volume and tone control network.
Click to expand...

Ignoring the dry/main signal, how far can you trace a signal from the reverb volume pot?
Can you trace it as far as the verb unit? If not, where does it drop out?

You know the drill; I certainly won't have the right answers, but who knows, maybe I'll have the right questions. :p
 
it comes from the reverb tank out to the reverb volume, then from the reverb volume back into the volume tone control stacks which eventually go to the grid of the preamp tube for channel two.
 
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