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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: Re: The ol' debuggin' blues posted by Vinnie on February 19, 2006 at 16:23:12:
First, when you say the input is jumping between 70-250mVAC, do you mean inside the chassis, like at the grid pin of the 6SL7 socket? Many inexpensive voltmeters won't read AC voltage in the presence of high DC voltages. This could possibly be your problem in the plate measurement. With the amp off and the power supply caps drained, clip lead and extra cap onto the plate pin of the 6SL7 attach your voltmeter to the non DC bearing lead of the cap (do not ground the lead) and test the amp again. If there is signal there and the plate voltage on the 2A3 IS near correct. Turn off the amp, drain the power supply, lift the 2.5k bias resistor on the 2A3 filament transformer centertap and insert your ammeter there. Turn on the amp and note the current flowing there. Turn off your amp. Think about what you have found out.Good luck,
Michael
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- signal - marnold 17:14:46 02/19/06 (0)
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