KEL34 making safe to work on

[Greg.]

Originally Posted by bob orbell

When I mentioned covers I did not think of small chrome covers, I was thinking of a cover that totally encloses both transformers as in some Icon Audio amplifiers, myself, I think all exposed transformers look naff. Bob

As in potted.

[willslenco]

Populated the board yesterday

[willslenco]

Thanks Pavel, I've now put it all back together :grin:

I've even fitted a proper IEC socket now and got rid of the redundant XLR speaker sockets.



Fired it up with a cheap pair of speakers to test voltages etc, but couldn't resist trying some sounds through it...

Nada :sad: although when I swapped the source to the tape input I did get sound - on left channel - so looked like at least a possible problem on selector or toggle switches.

So checked voltages and found left ECC82 k1/k2 were showing 0v and a1/a2 just over 400v :shocked:

Lets try a new ECC82 - that's better, spot on now :grin:

Both channels now working via tape in and fault traced to the toggle switch gone bad, replaced it and all is now good :cheesy:

It's now in main system and sounding very good indeed, with a beautifully silent background, much quieter than the other KEL34, which has a bit of a hum - hopefully I can remedy that when I strip it down to repaint.

And the bonus is I still have a brand new circuit board for the future.

[bob orbell]

Very good indeed, I commend you on your work but, one small, and to me very annoying issue, the input phono sockets are correct with the red on the lower line, but the speakers are upside down why please correct it. Bob

[A Stuart]

Always very satisfying to locate and sort out problems successfully.

Cosmetic detail - how about an attractive cap of some sort on the mains transformer bolt. Just looks very utilitarian compared with the suave sophisticated surrounds.

[bob orbell]

Aha, I didn't notice that Alistair, good call . Bob

[willslenco]

Thanks for the help and encouragement guys.

Sorry about the aesthetics but the speaker terminals don't bother me and are hidden at the back anyway.

And the bolt is as original, yeah a bit industrial but I'm comfortable with it.

[Richard]

Originally Posted by bob orbell

Very good indeed, I commend you on your work but, one small, and to me very annoying issue, the input phono sockets are correct with the red on the lower line, but the speakers are upside down why please correct it. Bob

These varied a bit on WAD/WD amps. Kit88 was as you describe Bob but WD88VA was as Malcolm's black amp. Both versions of KEL34 used XLR so no clue there.

Here's a pic attached of WD88VA terminals from when we were discussing Rigger's earth lift.

[Richard]

Originally Posted by willslenco

It's now in main system and sounding very good indeed, with a beautifully silent background, much quieter than the other KEL34, which has a bit of a hum - hopefully I can remedy that when I strip it down to repaint.

Have a check through the earthing Malcolm. Kel34 didn't use an earth lift and was very quiet so long as the exact routing described in the build sheets was followed. From memory there is no earth post and the signal ground is connected to the mains earthed chassis at the volume control. Make sure the paint is removed to allow that. Also check the input phonos are isolated. They come with those red fibre washers which usually work but if a socket moves off-centre it may become connected to chassis. Mine were ok but replacement with plastic shouldered washer type would be better. A bit of investigation with a continuity meter may be useful

[Greg.]

Originally Posted by willslenco

Sorry about the aesthetics but the speaker terminals don't bother me and are hidden at the back anyway.

And the bolt is as original, yeah a bit industrial but I'm comfortable with it.

Good for you. You’re contentment is what is important. The thoughts of others are inconsequential.