The Amp Garage

Hello Folks, I am hoping to establish the correct primary wiring colours on a 606-331 power transformer. I have just completed a rebuild but am getting very high B+ so I suspect that perhaps the power selector is fauly and/or in the wrong setting. The selector does not move comfortably between setti...

Thanks pdf64 - most interesting

I must add as a P.S. that my girlfriend is, understandably, fascinated by my conversations about the workings of amplifiers - what girl wouldn't be?

Whilst that is a perfectly feasable scenario, no, I had no reason to mess with what was (and now once again is) a fabulously sweet sounding amp. In fact I was discussing the point with my girlfirend this morning and saying that of all the components likely to fail, I would have put a potentiometer a...

Well, Much to my total astonishment and as a result of your suggestion, I replaced the INT pot and everything behaved as it should! I had previously removed this pot and tested it to ensure that the end to end resistance was good and the wiper gave a smooth variation accross the sweep. It appeared t...

Yes, that makes sense. I suspected that the oscillator circuit was Ok.
I will try that recommendation and report back
Thanks again,
Larry

Thanks so much for your advice on this. I am thinking back to when the problem occured. The amp has always had a tendency to hum but about 2 months ago whilst using it I noticed what looked like the beginning of one of the 6L6s to head towards red plating. having removed the valve in question I noti...

Hello again, Firstly apologies. you are of course correct in that I carelessly specified the bias pot as 250k. It is in fact 10k as you guessed. pin 5 wrt chassis : INT from -41.2 Volts to -8.35 Volts Bias from -54.6 volts to -29.5 volts Trem cap was disconnected during these tests. I suspect this i...

Hello Folks, Here is the bias circuit in my amp as an attachment (Vibroverb clone bias circuitry). Yesterday I replaced the .1uf cap from the vibrato circuitry with no improvement. This morning, as recommended, I disconnected the cap from the 250k intensity pot and moving the wiper away from the 55v...

Thank you all for your advice. I will carry out suggested tests today and report back. Also I noticed that there appear to be grid stopper resistors of 1.5k in series with pin 5. I do not see them on my Fender diagram. I will draw out an accurate representation of the actual power supply and bias co...

Hello Amplifier people. I am hoping that someone may be able to assist with a technical problem I am experiencing with a Vibroverb clone which I bought about 6 years ago. The Vibrato (tremolo actually) has ceased to work. This in itself is a minor irritation but I didn't realise that unless the inte...