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RSC Bass Major (1963?)

Picture
I can't remember what I paid for this with no valves, but I was attracted by the green spotty pattern of the covering, the black front, and the proper 1/4 inch jack sockets on the front.  Many of these Linear amps had phono sockets on the front or side.  It also looked old. The previous owner said one of the EL34s glowed red and smoke appeared at the valve base when he switched it on.  As I had plenty of valves floating about it wasn't a problem reinstalling them.

I think this was a factory built amp rather than a home build, but either way, the components are pretty cheap.  Note the old kitchen drawer handles!

First to go were most of the blue Hunts coupling caps.  One of these was leaking dc onto the grid of the glowing valve and effectively turning it more than full on, hence the red plate and localised burning dust smell.  I can't find a schematic for this model so used the similar 30 Watt Bass Regent one as a starting point.

It's sad to see so many dodgy resistors with metal caps on the end!  One of these was in two pieces.  I changed some that were obviously off spec but really they should all be replaced with decent ones.  However, I just wanted to get it working for now. 

Update 7 October 2013
I decided to finnish this one off with some new F&T filter caps and one or two key resistor changes.  It was necessarry to enlarge a hole in the chassis and add a clamp and grounding wire. Again, one of the metal ended resistors disintegrated and had to be replaced.  As this was a 220k Ohm input resistor I replaced it with a 68K, so it now has a high gain channel and one stock.  It's actually quite a nice sounding amp now, louder, more willing to break-up and the hum has gone completely. Still some hiss so I might replace some more resistors.
13 October
The hiss has been greatly reduced by replacing three key resistors.  This is a really cool little guitar amp now, quite Voxy!  Kicking out 15 Watts clean and around 23 Watts at full clip!
Musicman RP 112 Sixty-five            JMI Vox AC 10
Elpico AC52                                     Carlsbro CS 60
Filmosound Amplifiers                      Hiwatt Lead 50R
Lab Series L2                                   Burns
Lab Series L5                                   Fender Twin Reverb
Selmer Constellation 20                   Fender Musicmaster Bass
Selmer Treble & Bass Mk 2              Impact 60
Schaller KV40                                   Northcourt 50
Fender 5F1 Champ                           RSC Bass Major
Traynor YGL 3 - Mark 3                     Mystery Amp
Watkins Westminster                         Denco 912-Plus
Denco 912-Plus                                 Interesting Waveforms
Wem Dominator Mk 3                        Mullard 5-10
Wem Watkins Copicat Mk 3               Decca Amp
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  • Repairs & Servicing
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    • Business Card
  • Filmosound
    • Filmosound Guitar Amps
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    • Testimonials
  • Contact
  • Amps & Stuff
    • WEM / WATKINS >
      • Watkins Clubman
      • Watkins Westminster
      • Watkins Westminster Mk 9
      • WEM Control ER15 No. 1
      • WEM Control HR 30
      • WEM Dominator Mk3
      • Watkins Copicat Mark 2
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      • Wem PA100
    • Baldwin Burns Amplifier
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    • Elpico AC52
    • Leo Fender >
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      • Fender Twin Reverb 1972 Silverface
      • Fender Blues Deluxe
      • Fender Musicmaster Bass Amp
      • Musicman RP 112 Sixty-five
    • Gibson >
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      • Gibson Falcon GA19RVT
      • Lab Series >
        • Lab Series L2 Service and Repair
        • Lab Series L5 100W Combo (Gibson/Norlin)
    • Hiwatt Lead 50R Combo
    • Marshall >
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      • Marshall Superbass Mk2 100W Head and Cab Service Repair
    • Miscellaneous Amps >
      • Harmony H307x
      • Hotpup 5F1 Champ
      • Impact 60
      • Mystery Amp
      • RSC Bass Major
    • Orange >
      • Orange OR120 1970s Service and Repair
      • Orange TH 30 repair
    • Schaller KV 40
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