Help needed!! Bluesbreaker re-build problem!! Help?

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Help needed!! Bluesbreaker re-build problem!! Help?

Postby thebloosman » Wed Dec 12, 2012 3:54 pm

Hi guys,

I'm attempting to get my amp going for the first time, it's a....

Jtm 45 bluesbreaker re-issue-re-build with point -point board, & marstran RS OT, all wiring good, tested fine until power tube test section, i did had a few problems, now sorted but I have created/made another problem,
All tested fine until power tube test, got the tubes in place, speaker connected, all pots to 0, turn standby on and I get this "MASSIVE Loud farting/motorbike noise! WTF??

Any ideas guys??
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Re: Help needed!! Bluesbreaker re-build problem!! Help?

Postby David B » Wed Dec 12, 2012 4:06 pm

Got pictures?
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Location: Rockville CT

Re: Help needed!! Bluesbreaker re-build problem!! Help?

Postby thebloosman » Wed Dec 12, 2012 5:19 pm

Image
Image
Image
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Re: Help needed!! Bluesbreaker re-build problem!! Help?

Postby thebloosman » Wed Dec 12, 2012 5:40 pm

What do u need to see guys???

Just a thought....I'm using JJ 6l6gc POWER TUBES, as I'm waiting on my kt66's arriving, will this make any difference???
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Re: Help needed!! Bluesbreaker re-build problem!! Help?

Postby thebloosman » Wed Dec 12, 2012 8:29 pm

SHE'S ALIVE!!! Whoooohoooooo!!!

The primary wires were around the wrong way...
I swapped them over and the loud hum has gone, great!!!!

But.....

The bias is off....I'm using 6l6's in place until my kt66's arrive but the bias is only around 25-26 on the meter with the bias pot completely counter clockwise....any ideas there????
thebloosman
 
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Re: Help needed!! Bluesbreaker re-build problem!! Help?

Postby neikeel » Thu Dec 13, 2012 1:06 pm

I don't wish to sound particularly arsy but there were two other threads that had answers to your questions and no follow up reply from you then another thread in another section :roll:

The bias setting will depend on the method you are using and the plate voltage. If you are using the stock PT and a modern GZ34 then 400V will be about right on pin 3 so 45mA would be your target.

As a rule KT66s will draw more so you can alther the bias resistor now for these tubes or play it as is and wait for the definitive valves or..........
Neil
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