It doesn't work! :(

fred
Jr. Member

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Posts: 57

It doesn't work! :(

« on: May 11, 2008, 08:18:21 PM »

Hello, finished my amp, followed the paul ruby tests and everything was looking peachey up until i went to bias the valves. All the volume controls were at 0, only the mid treb and bass controls were at 5, everything else at 0.

All the valves are in and the bias is set to the most negative it can. I flick the on button BURRRRRRRRR!!!. A very loud oscilation. Any ideas? I am using EL34s if it helps (cracked a 6l6 trying to put it in, doh)
what should i do?


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bluegate
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Posts: 63

Re: It doesn't work! :(

« Reply #1 on: May 11, 2008, 10:02:20 PM »

If its a loud high pitched oscilation than swap the two primary OT wires.
Happened to me, and after the swap the amp worked fine.

Look at recent fotos to see were the blue and brown wire is soldered to which tube.
Also read that sometimes the wire colours are wrong, measure the resistance between blue and brown and blue or brown and red.
Blue-Brown should read twice as much as Blue-Red or Brown-Red.
Red should be Centre Tap.

Good luck.


« Last Edit: May 11, 2008, 10:06:47 PM by bluegate »	Logged

fred
Jr. Member

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Posts: 57

Re: It doesn't work! :(

« Reply #2 on: May 12, 2008, 04:20:10 PM »

yep, that was the problem, i followed the pics after peoples suggestions but seems like the layout was right all along.
thanks blue!


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hywelg
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Posts: 896

Re: It doesn't work! :(

« Reply #3 on: May 12, 2008, 05:53:48 PM »

Glad that was an easy fix. How you liking it? Get that power amp opened up and hang the neighbours at least for 10 minutes or so!


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