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Rotel RA1312 heavy amp problem

This large rack amp was last used in a social club, working order, many years ago. Not powered up since and only front lamps now come on. I assumed,initially, it was just lack of amp - preamp interlinks but no. I'm loathe to explore unnecessarily if its an equally silly error as it is that nasty brittle age hardened single conductor wiring loom and wire-wraps everywhere - typical 1960s, probable manu date 1969. Good stable +/-50V dc rails and cold "diode " checks of all the o/p trannies look ok but the speaker line relay does not click over. Any inside gen ?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N Cook
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Just use RCA cords those interconnects are 99.928467% RCA phono jacks anyway. Secondly, I doubt it could be as bad as a Sansui 3000A or some of those tiny sports cars you guys made ;-)...if it is c.1969 as you say it's not going to be like that 1603? "monster" receiver with plutonium pellets and handservants needed to feed it. Just a lot of capacitors, I'll bet, and one of them ought to be bad (especially the big ones over 1000 mf), causing the protection circuit to abort liftoff. Second place to look is all that wiring, third maybe any block resistors. What I've gathered from some

1968-71 sets (having an unplugged, unpowered set discharge through my stereophones was a "thrill" too), so I'm just theorizing, still hope it helps. Those era sets are so charming but so arcane as I was maybe 2 or 3 and things were much different by the time I got to looking in them at maybe
  2. > This large rack amp was last used in a social club, working order, many

wire-wraps

trannies

Reply to
Steven Dinius_

and

causing

maybe

is

Thought i'd found problem I removed the large cap that seems to be for timing thinking it was leaky and powered up and the relay clicked over at power up, but replacing with a good one returned to always off. The line back from the main amp settles out to 0V soon after power up so that is probably ok, will try replacing the small tranniess in the relay ANDing and relay drive next as prob seems to be in the protection circuitry

Reply to
N Cook

cured - rail monitoring problem - write up will be on one of the repair brief files on URL below

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N Cook

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