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Old 9th June 2021, 03:49 PM
willslenco willslenco is offline
Join Date: Jun 2021
Location: Swansea
Posts: 53
Default Re: KEL34 making safe to work on

The probes to make discharge tool and the gloves arrived yesterday from Amazon and this morning the resistors from HiFi Collective - a huge shout ou to them as I only ordered them yesterday afternoon.

I made the discharge tool out of one probe lead and a 1k 10w resistor.

Then opened up bottom of amp, donned the gloves, attached discharge crocodile clip to one of the neutral speaker posts and took readings at 'a' pins on EL34s - only 38v but amp had been off for a couple of days. But I'd made the discharge tool and I was going to use it, a couple of seconds with it and 0v observed.

Decided to do as Nigel suggested and leave the circuit board in place to change resistors. They all unsoldered easily and solder sucker cleared holes although one solder pad got detached. Fitted the new resistors, bent to right gauge and legs trimmed to go through board but also leave a good height above board to allow cooling, then flowed solder to joints keeping iron in place a little while to hopefully flow solder through to other side of board especially in the case of the one with the missing pad.

Then checked resistors for continuity with rest of circuit, all good. Also tightened the toroid's fixing bolt as it had loosened in transit.

It's back in system and playing very nicely, it actually sounds better IMHO.

A great result and many thanks to those who gave good advice, especially Nigel and Alan.

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