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Replacing Burnt Components on Gallien Krueger RB400 Bass Amp
Replacing Burnt Components on Gallien Krueger RB400 Bass Amp
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Old 20th February 2018, 12:50 AM   #31
Cheeto333 is offline Cheeto333
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Hmm. Looking at the schematic, the rectifier inputs are the two blue wires (taps 3 and 5), which I measured as ~80VAC. Yes, it appears to be center-tapped, so these readings are expected, correct?
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Old 20th February 2018, 02:04 AM   #32
Cheeto333 is offline Cheeto333
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As a note: the bulb did not glow brightly at 4 VAC on the variac, but more than I thought it should have.
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Old 20th February 2018, 02:41 AM   #33
PRR is offline PRR  United States
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A 120V bulb can't glow at ALL with 4V from the Variac.

So you have something wrong, but we can't know what.
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Old 20th February 2018, 03:16 AM   #34
Cheeto333 is offline Cheeto333
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Is it safe to connect the secondaries of the transformer one at a time until the bulb begins to glow? That might help isolate the issue.
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Old 3rd March 2018, 01:31 PM   #35
thoglette is offline thoglette  Australia
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Thought I'd posted this earlier.

Better to first disconnect the secondaries individually; disconnect and check the PSU electros. Then check secondaries with rectifiers and electros ONLY.

That will at least establish if your power supply is OK.
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Old 17th April 2018, 12:01 PM   #36
thoglette is offline thoglette  Australia
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Well, I'm guessing it all ended badly :-(
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