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Another Leak Stereo 20 restoration

Mike P

Trade: Pickwell Audio
I appreciate that there have already been several Leak Stereo 20 restoration threads here but here I go again with another one.

This is my fourth Stereo 20 restoration and by far the most in-depth restoration so far.

I bought this particular example from @Rosewind a few years ago and it has been in my 'to do' pile until a few weeks ago, when I finally got around to tackling it.

I bought it knowing that it had been rebuilt at some point (as evidenced by all the non-original parts) and I naively thought it would therefore be a easy refurb. :rolleyes:

As you can see it had been crudely sprayed satin black at some point. All of the valve bases apart from the one for the GZ34 have been replaced, new speaker wire bindings posts and phono sockets have been fitted and the circuit board has been *rebuilt* with many replacement parts.

20210503_150220 by Michael Pickwell, on Flickr

20210503_150237 by Michael Pickwell, on Flickr

On closer inspection though the rebuild turned out to be a really truly awful job. Very messy with poor soldering everywhere. Oh dear.

20220501_190232 by Michael Pickwell, on Flickr

Oh dear oh dear. :(

20210503_150426 by Michael Pickwell, on Flickr
 
Wow, what an absolute mess! I hope it was cheap! By saying that if the transformers and mainboard are ok it can be brought back to mint fully functional condition, especially given decals etc are now available.
 
The fasteners were first soaked in thinners to dissolve the black paint. They were then left in an acid solution to get rid of the rust before being lightly scrubbed with a soft wire brush and then soaked in oil to protect them for corrosion.

20220507_093130 by Michael Pickwell, on Flickr
 
The finished underside.

Finished underside by Michael Pickwell, on Flickr

I was planning to use K40Y-9 PIO caps again but couldn't find them for a sensible price (no doubt not helped by the situation in Ukraine).

Thankfully member @disco very helpfully offered to sell me a set of K42 PIO caps, which he found to be sonically indistinguishable.

The big electros had already been replaced and were in good shape. So they were stripped of their plastic sheath and and painted along with the chassis etc.

The resistors are mix of what I had stock and new Takman carbon films.

Only the two yellow poly 1000pF caps were reused from what was there previously!

The mains switch was quite a neat solution and the power outlet socket was missing anyway, so I tidied it all up and reinstalled it.

The wiring isn't as tidy as I'd like but miles better than it was. I spent hours making it as neat as I could and replacing damaged bits of wiring in the original colours.

The bindings posts were retained but I replaced the phono sockets again as the ones fitted were a bit knocked about and tatty looking.
 
That looks fantastic, as I would expect from you, Mike. A few questions...

Why did you scrub the board before removing the components rather than after?

What in particular drew the ‘oh dears’? The type of components used or the fact that it looked as if they were laid in er, much the crooked way they would have been if I had been doing the job?

What exactly isn’t ‘as tidy as you would like’ about the final result? I’ve examined the photos using a powerful microscope and can’t see anything problematic.
 


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