Fault in ECL86 - UK Vintage Radio Repair and Restoration Discussion Forum

John_BS · 10th Jun 2021, 8:40 pm

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

Ed_Dinning · 10th Jun 2021, 9:06 pm

Hi John, it may or may not have a lot of life in it yet.
Analyse the circuit and see if the fault re-appears it will cause expensive damage. If not a note to self within the machine as to what the problem was

Others may disagree

Ed

John_BS · 10th Jun 2021, 10:09 pm

Ed: no, it's got 100K to both anode & cathode, so only passes 1mA !

John

kalee20 · 11th Jun 2021, 12:25 am

It's probably some debris, unfortunately rattling around in the valve.

If it works, leave well alone - it may carry on fine, but die if you pick up the equipment and turn it on its side.

As nothing is going to get damaged, according to your checks, you might as well carry on and enjoy its service.

John_BS · 11th Jun 2021, 10:27 am

It's back in and working, so fingers crossed!

Thanks for the advice.
John

10th Jun 2021, 8:40 pm	#1
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,780	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

10th Jun 2021, 9:06 pm	#2
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Fault in ECL86 Hi John, it may or may not have a lot of life in it yet. Analyse the circuit and see if the fault re-appears it will cause expensive damage. If not a note to self within the machine as to what the problem was Others may disagree Ed

10th Jun 2021, 10:09 pm	#3
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,780	Re: Fault in ECL86 Ed: no, it's got 100K to both anode & cathode, so only passes 1mA ! John

11th Jun 2021, 12:25 am	#4
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,081	Re: Fault in ECL86 It's probably some debris, unfortunately rattling around in the valve. If it works, leave well alone - it may carry on fine, but die if you pick up the equipment and turn it on its side. As nothing is going to get damaged, according to your checks, you might as well carry on and enjoy its service.

11th Jun 2021, 10:27 am	#5
John_BS Octode Join Date: Dec 2008 Location: Wincanton, Somerset, UK. Posts: 1,780	Re: Fault in ECL86 It's back in and working, so fingers crossed! Thanks for the advice. John