Fault in ECL86
I've been revisiting a Dynatron record player which I'd previously "restored" circuit-wise. The original Mullard ECL86's tested 100%, but having changed the cartridge for a more appropriate type, I was greeted with truly epic distortion.
Big sigh and everything out of the case again: the phase-splitter triode should have 30 odd volts on its cathode, but it was up at 100V and only a few volts below the anode. Not having found any component problems, I removed the valve and tried it on the AVO. It said there was an issue with insulation "anode to rest". When I removed it and gave it a firm tap with a screwdriver, all came good. Back in the record player and the biasing is now correct. Is it safe to leave this as it would be a shame to replace one of two original valves with 100% emission.
John
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