RSC Guitar Amplifier.

[Valvepower]

Hi Colin,

If you are interested, I have the original instructions and circuit-diagram which I could scan and post.
Regards, Colin.

Yes please, I’ve be very interested in seeing the original circuit and instructions.

I’ve have had problems where point to point prototypes worked fine and I’ve had subsequent problems when the circuit is transformed to a neat tag or a PCB layout!

Terry.

[ColinTheAmpMan1]

Here you go. The dark marks are residues from the application of sellotape when the document fell apart yonks ago.
I have included my redrawn circuit diagram, since the original is not too clear in places.
I might even be able to find a circuit diagram for my modified amp, with the use of circuit boards, two channels with independent tone-stacks (one with tremolo with speed and intensity) and presence control. When I did this initially, I got a feedback howl on first switch-on which horrified me. It was solved by altering the lead-dress so that two wires were further apart (on the phase-splitter, if I recall correctly). Lead-dress can be very important; what looks like a lovely neat amplifier with wires all in straight lines and laced together, with perfect right-angle bends can be a recipe for an amp with instability problems. If no-one can see it and it works fine, there is little point in being overly tidy.
I can only attach the first five pdf files to this message, so I'll have to submit abother one with the rest.
Regards, Colin.

[ColinTheAmpMan1]

The rest.
Colin.

[sparkymike]

All the above drawings and circuit are very helpful, thanks Colin, although my amp is a bit different, but certain parts of the circuit follow suit and are very similar.
Anyone got an idea what the grid voltages should be on ECL 82 and ECC 83valves?
Mike.

[AC/HL]

Unless they are DC coupled, all first grids should be zero. The grid bias is the cathode voltage, which is positive WRT the grid.
If you can measure anything at the grid it means either a leaky coupling capacitor, or a leaky valve (or valve holder)

PS. You probably have this, but the DC voltages are here -
http://www.vvttransformers.co.uk/drb...919_chap13.htm

[sparkymike]

Well according to my old wind-up megger, at least two of the electrolitics are reading down to zero, but will have to desolder a few bits first as the megger is probably reading through parallel resistors etc. On one of these caps, the modern digital ohmeter reads 2.6 meg, but vintage megger reads zero !! So it is looking like I will be changing a few caps first, before anything else.
Mike.

[maninashed]

Mike, the Megger isn't really suitable for testing electrolytics, use it for wax/paper/polyester types only. Due to the way electrolytics are made, they all exhibit some leakage. Best to test them using an ESR meter as it is the "equivalent series resistance" that is important with electrolytics.
Bill

[phill1029]

I would be grateful for a copy of the Linear amp instructions and schematic, as I have one of these to rebuild.
Thanks