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Leak Stereo 20

Tony L said:
If you were really picky about aesthetics a little filler and sanding on top would fill the dip prior to priming and painting. With a little effort you could get it looking original.

PS FWIW I’ve clearly not understood the issue here. The Stereo 20 chassis is ground. The signal return is ground. The schematic says it is ground. All of the black ground wires go back to a case screw on one of the big can cap mounting lugs. Everything continuity beeps to the earth pin on the mains plug anyway. Leak grounded the capacitor can, and very deliberately so by the looks of things. I was actually a bit worried by not doing so on my TL12 Plus rebuild, though left the F&T cap plastic skin on as I was mounting it internally and wanted to be sure it couldn’t short anywhere in any scenario even if it became loose (which it won’t!). As ever my aim is only to sympathetically restore. I have no interest in second-guessing or “improving” these classics.
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Tony, I'm not convinced that the original caps' cans were grounded through their clamps.

PXL_20220402_152157600~2 by Garf Arf, on Flickr

Looks to be too much paint on the cans.
 
chiily said:
Tony, I'm not convinced that the original caps' cans were grounded through their clamps.

PXL_20220402_152157600~2 by Garf Arf, on Flickr

Looks to be too much paint on the cans.
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That is a good point. I don’t know. That said the same would apply to the can caps in the Stereo 20 I restored upthread as they had some filler, a good coat of primer and two coats of top-coat. I didn’t make any attempt to scratch back paint etc. As stated my intention is restoration, nothing more. I just try to do things how they were, and where possible undo past less-sympathetic restoration attempts.
 
steveinspain said:
Has anyone here actually heard one of these valvepower amps?
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Given that the difference between them and the English Acoustics version is around £4k, I am interested as a prospective Stereo 20 buyer (who has not the foggiest about valve amps and has never owned one before, apart from the preamp in his Eden bass head....).
 
It’s a long time since I’ve posted here! My cousin turned up the other day with a Leak Point One Stereo, did I want it? It is in excellent condition, but of course it needs something to power it. So I’ve put it to one side for now and bought a Stereo 20. Of course I did. It’s off ebay and is in excellent cosmetic condition. According to the seller, a ‘Leak expert’ has serviced it and replaced pretty much all components underneath, which I shall go through and review/replace as required in due course. Two things worry me, though, and I’d appreciate some help and advice.

The green ‘safety’ resistor has been replaced with two ceramic, wirewound resistors, 5W 120 Ohm in parallel. Is that ok? The second thing is there are two additional electrolytics that seem to have been added: A 47uF 500V with the +ve connected to R21 and the negative attached to the negative of a 22uF 500V, whose positive goes to Pin 7 on the Right output transformer, The negatives of the two caps are earthed. Does anyone know what these are for, why they are there and whether I should take them out?

Any help gratefully received. If I could post a photo, I would, but sorry, I can’t.
 
My understanding is R21 should be a 100 ohm 3 watt wirewound, its what I've used. The other alterations I can't help with but if I was you I would just return the component values to stock.
A photo of the underside of your amp would be helpful, there are some extremely knowledgeable folk on here who can spot potential issues a mile off.

TS
 
Thanks, Tony, that's what I thought and why I worry that it's been reduced to 60 ohm. I'm trying to upload a photo, but it keeps telling me 'Your content can not be submitted. This is likely because your content is spam-like or contains inappropriate elements'
 
Ok, I needed 5 posts before I could post an image. I've had an account here for years, but changed my email provider and then forgot to copy my password when I dumped LastPass, so had to start again as a new member.

Anyhoo... here's my Stereo 20. It is excellent on the outside, but I cannot live with that soldering job. So can anyone help with the reason for those black electrolytic?

 
I hate to say it, but I’d just strip that right out and start again! There is a lot of weirdness there to my eyes. Just get the schematic, bill of materials and check every single component. I suspect it would actually be quicker to just strip it down to bare tag boards and do it right. Probably not what you want to hear, but that isn’t right, and it wasn’t done by anyone who understands these amps.
 
The extra black caps give the impression of being in parallel with the main reservoir and smoothing caps, C13 / 12. If so it would suggest that someone thought they had a PSU hum problem and wanted to bump up the standard values. This could overload the rectifier.

As Tony says, get it back to standard.
 
You're right, of course, Tony, it's a pretty shocking job. It gives me the willies just looking at it. It arrived with Parcelforce in a big box, all the valves carefully inserted in their sockets and surrounded by random bits of foam. One of the EL84s didn't make it and red plated once switched on, so I switched off pretty quickly. It smelled hot, like really hot. Music did come out, though. I still wonder what those caps are for, though. Here's the outside as delivered.
 
Ah! Thanks Barry, that makes sense. I will strip and refurb. It's going to drive some B&W DM4s that I've been refinishing. Front end will probably not be the Point One, but a B4 that I used briefly with headphones but can now be repurposed after all these years. I already have 5 stereos in the house so I won't be short of a tune while I fettle! Thank's guys. I'll be back.
 
Looks like a good candidate for a full rebuild. As an aside I don’t know why some people choose the components they do. Pet hate : those tiny blue film caps used in place of axial types. So easy to source proper types online and just looks better when all correct types used. Looks like the pcb material has been cracked at the top where the mounting clip is missing. Hopefully somebody here might have a spare they can part with. Otherwise there’s nothing that can’t be put back to spec. again. These are great fun to work on and you’re rewarded with a truly fantastic sound at the end of it. Look forward to seeing its progress :)
 
I'm trying not to worry about that crack! AFAICT it shouldn't make a difference and I'll pretend I don't know about it until I've forgotten. Which shouldn't be that long these days. I think I've sorted all the caps - Ive gone for Ruskie PIO for C3,4,5 and 6 and polystyrene for C1 and 9. I notice that C10,11 and C12,13 are 16uF+16uF so I think I'll need to replace those with 32+32. And now I'm now fretting about resistors. I'm thinking all carbon film except R14, 15 and 21 which I think need to be 3W? What about the wattage of the rest? Can I just choose on the basis of size to make them look right? I'd rather order a compete set of replacements before I start desoldering and testing individual components to see if they can remain in place.
 
SimeonJ said:
And now I'm now fretting about resistors. I'm thinking all carbon film except R14, 15 and 21 which I think need to be 3W?
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I went with 1W Takmans as, unlike many, they are long enough to span the tags. Most folk here seem to have done the same. IIRC the original Leak were mostly 0.5W aside from a few of locations that were 1W, and then the green one. Annoyingly you won’t find half-Watt with long enough spans these days.

I’d be wary of usung too high a value as it is always better that a resistor blows than the transformer in event of a failure. I actually reversed-out a choice in my TL12 Plus build a few months ago to lose a couple of higher Wattage 270 Ohm resistors that could have been problematic in a failure scenario. Where possible stick precisely to the Leak bill of materials. They knew what they were doing.

PS I’d be inclined to glue the board crack. If you are dropping the board out, which I’d recommend given the amp has been rebuilt previously just to check the above-board wiring and clean everything, it could probably be glued and reinforced from above out of sight.
 
Thanks, I'll ammend my resistor plans accordingly. Mine has a an 8162R and 8778 output transformers , so I'm basing component values on that schematic. I suppose I should grit my teeth and check out the top wiring, too, and fix that crack while I'm at it. I've also been having a closer look at the wiring the last guy did and he managed to rest his soldering iron against quite a few wires in there.
 
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