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The Altec 1568 amplifier (2 EL34, 5U4BG recifier, 40 watts mono) uses a Peerless 6288 power transformer.The 6288 needs to be replaced or accurately rewound.
The amp goes on normally, sounds OK for about a minute or two,
then the B+ starts to drop and the transformer over heats and starts to smoke.
At startup voltages are normal. No shorts.Thanks,
Stager Sound Systems
Edits: 04/22/09 04/22/09
From your description, it appears the transformers are working. Is it possible that the tubes are losing bias and going into thermal runaway as things heat up? This could be leaky coupling capacitors, for example. Or a bad bias supply - the rectifier appears to be selenium, which have a reputation for failing with age; also the 50uF electrolytic capacitor is likely dying if it's original, or the bias pot may have a dirty contact.
All this is based on a cursory glance at the circuit, which I found here:
Hi Marc:
We don't do rewinds for any number of reasons--- cost and accuracy being
the first two :=)
We should have this blueprint in the archives-- however, at this time, due to an ongoing injury I am not taking on any new work larger than units that fit in channel frames.
MSL
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Builder of MagneQuest™ & Peerless™ transformers since 1989
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