Test readings for KEL84 without valves - World-Designs-Forum

Sparks · #1 22nd April 2013, 08:17 PM

Hi all

Got a problem with my KEL84. One of the 84s is glowing within a minute or so of switching on. When swapping round the valves it's always the same position that glows.

Is there a troubleshooting procedure to follow with the valves removed so I don't break it further?

Cheers
Sparks

Phil Y · #2 22nd April 2013, 11:01 PM

Hi Sparks,
100uF cathode cap in that position gone short maybe ?

Phil.

Sparks · #3 23rd April 2013, 02:45 PM

Hi Phil

Thanks for that. Had a close look and one of the caps was a bit ripe. Took it off and it was a 220uF, as were the other three! Was this a mod or just a mistake?

Anyhoo, replaced all four with the correct value 100uF, and also replaced the four 270R 1w resistors, and now it's BACK

Thanks again

Cheers
Sparks

Phil Y · #4 23rd April 2013, 07:56 PM

Hello Sparks,

100uF caps is correct to the circuit diagram. 220s would not do any harm I think but I don't know why they would be fitted.
Anyway glad to hear all is well again. How long was any one valve subjected to the fault ? It would not do them much good it it was for an extended period.

Regards, Phil.