GT bias tool failure? fixable?

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GT bias tool failure? fixable?

Postby selmerelmer on Fri Feb 21, 2014 8:20 am

Recently while attempting to set the bias on a 50W amp using my GT Bias tool, a preamp valve base decided to play up (intermittent pin connection) and in the process cause loud noises to come through the speakers, obviously with increased current and power being dissipated in the EL34 as a result. Since then I can get no reading when using the GT Bias tool. I've tried it in other bases and valves etc. It seems the bias tool has been killed?

What is inside them? is it just a close tolerance resistor? Anything else inside? Does anyone have a schematic? On close examination it doesn't look as if it is possible to take the bias tool valve base apart, it's not obvious anyway. Has anyone repaired one?

I'm in the UK. BTW, GT don't appear to sell the bias tool any more - is that ominous?!

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