$5 SE amp... but is it fried?! - diyAudio
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Old 15th January 2004, 08:39 AM   #1
SHiFTY is offline SHiFTY  New Zealand
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Talking $5 SE amp... but is it fried?!

Well I picked up an ancient Sony reel to reel recorder for $5 from a junk store. It was a pretty solidly made stereo beasty, but in pretty bad exterior condition.

Anyway I opened it up, turns out it has a pretty sweet amp in it, 6AQ5 in SEP in their own amp chassis, which can be totally removed as a self contained unit (with cool retro mesh!)

The power transformer is beefy too, and nicely potted (black box in the top right of the photo.)

Also in it was a telefunken ECC83... made by Mullard!? Weird...

Anyway it seems that the output trannies might be fubared, one the primary resistance measures 450 ohm, the other 1300 ohm. Not shorted to ground though.

Any ideas? Should two identical transformers vary this much?

Cheers
Henry
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Old 15th January 2004, 11:32 AM   #2
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The primary resistances of the two transformers should be a closer match. Did you remove the 6AQ5 tubes before measuring?
Do the trannies have a screen tap?
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Old 15th January 2004, 01:31 PM   #3
dhaen is offline dhaen  Europe
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Measuring inductors with an autoranging meter can give misleading results.
If you use this kind of meter, I suggest repeating the test with the secondaries loaded or shorted.
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Old 18th January 2004, 04:13 PM   #4
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Noticed A black spot on one of the transformers ,is that the one that reads low .
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