McIntosh C20 - can and should I bring it back from the dead?

Thanks Hipocrates! Just taking it one step at a time. Wish I had more cash to rip into the chassis, but will have to do it slowly.
You will get there, you have the most important thing to do it (brain)....the white vinegar stinks, but do wonders, I've used on rusted planes, chassis, and speakers.
 
My parts are coming in. Today my fabric to re-line the glass rails came in, “flocked back adhesive fabric” which is the same stuff used to line jewellery boxes and ring boxes. Essentially thin, adhesive backed velvet or faux velvet:

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Very cheap and I have enough now for about 700 amps o_O

I’m still thinking about how I’ll treat the rails. I’ll be heading over to pickup my CNC plasma cut bottom panel this week. So may play around with the idea of making new rails and end panels from scratch on his CNC. Need to see if he can make it work first. If I can make all the rails for less than $100 I’ll still be way ahead instead of buying just end panels from the US.
 
From early on, yes, it started breaking it down, but I was using completely encrusted axe heads. I was hoping it might help you safely remove rust, and not precious metal.

No sweat... it just doesn’t seem to be doing much. Sandblaster it is then!
 
Question for the experts. Is it an issue if I powdercoat the top panels? I’ve seen some comments that top panels need some paint worn off on screw holes so that it electrically couples the entire chassis for its noise isolation properties.

Wondering if powdercoating the top covers would be an issue in this regard?
 
I don't think it would be a problem, you could remove a little from the underside, or place a star washer between the cover and chassis, if there is an issue
 
Good ideas @s-petersen, in the end I decided to paint them like the factory did, as it will allow me to add some body filler to fix up the rusty parts, plus I can scratch the screws in a little to get the chassis grounded.
 
Well thanks to @onwardjames and his vinegar suggestion, we have a result with the painted parts.

In the tray the results were underwhelming, but once I started spraying them with the garden hose to clean them up, both the paint and rust was washing away with the water :eek:

Here’s the results fresh from the baking soda bath:

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All the parts came out really clean, however the rusty parts still needed some final touches, so I got my hand sandblaster out and decided to finish the job.

After blasting:

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Obviously much better :)

Finally I put a layer of body filler on the 2 panels (top parts) where the rust was which will get sanded mostly off tomorrow and should leave a perfectly flat panel ready for some satin black paint:

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Looks like I could have a few parts of this preamp complete before the end of the week :trebon:

I also have 2k spraying capability setup at home, so I’m toying with the idea of buying some satin black base colour and doing it properly. I’m pretty new to 2k but I assume it’s tougher than regular rattle can?
 
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@ neevo I am so happy for you!! Those panels turned out GREAT!!

This is a Smithsonian quality restoration. Enjoying immensely.
 
Thanks very much. Not sure it’s quite there but the will is definitely there to get this thing back and rocking.

Today I sanded back the top panels and set about painting them in satin black. As expected the top panels are showing the rust spots through which I suspect is the way the paint has laid on the body filler (the same happened on my AR speaker build front baffles). So the next stage will be to let the paint fully cure before the top panels will be wet sanded with 600 grit before getting another couple of coats of paint.

Pics to follow.
 
I’ve also kicked off the parts acquisition process. Items that are essential and hard to find so I’ve prioritised them over things like chassis rechroming.

Currently I have a mint condition faceplate from Mcintosh Audio in the US.

Next up I’m ordering some genuine Mcintosh feet and original case screws from Audio Classics. I’m pretty sure the feet aren’t original to the C20 but I wanted genuine Mcintosh feet at least. They also have the genuine chassis screws though which I need as some of mine are not original and I absolutely want original screws. That will be ordered immediately.

Lastly I’ll be ordering a replacement volume control. I’ve found someone that makes replacements with the included on/off switch to at least factory specs and is suggesting they are an improved unit over OEM.

There’s still much more to buy for parts but currently the above are the ones I’m most concerned might disappear, so they’ll be purchased first, then I’ll move on to the chassis rechroming.
 
I’ve found someone that makes replacements with the included on/off switch to at least factory specs

I think that you will be surprised when you will use this pot
I do it myself too and I know about what I am talking about

so they’ll be purchased first, then I’ll move on to the chassis rechroming

I just remind you that original chassis is not chromed , it is made with a bath in chemical product
 
@clinic-audio are the replacement volume pots good to use? Would I be surprised in a good or bad way?

Also any idea what the original finish is on the chassis? I was thinking if having it satin chromed as is would look very similar.
 
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