Late '68, early '69 restoration

Info for maintaining and tweaking your amp to perfection.

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beaulieu
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Post by beaulieu » Sat May 31, 2008 5:27 am

the insp tag and half of the original rear panel are gone!
69 SuperBass Plexi
12000 Series Bulid
73 1987
68 Nos 50 build
2554 Combo
2550 Silver Jub stack
71 LesPaul Deluxe
68,71,73 4x12

beaulieu
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Re: Late '68, early '69 restoration

Post by beaulieu » Mon Aug 03, 2009 8:53 pm

Wondering if its time to do this to my 69 100 watter?? I couldnt look any worse and probally get better.My chassis could use a good cleaning!!
69 SuperBass Plexi
12000 Series Bulid
73 1987
68 Nos 50 build
2554 Combo
2550 Silver Jub stack
71 LesPaul Deluxe
68,71,73 4x12

ledzep443
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Re: Late '68, early '69 restoration

Post by ledzep443 » Sat Aug 07, 2010 8:02 am

Wow George! I can't believe how "neat" you make the wiring look. No matter how hard I try, my builds always end up looking like a squirrel's nest! :mrgreen:

somethin'else
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Re: Late '68, early '69 restoration

Post by somethin'else » Wed Aug 11, 2010 8:04 am

ledzep443 wrote:Wow George! I can't believe how "neat" you make the wiring look. No matter how hard I try, my builds always end up looking like a squirrel's nest! :mrgreen:
You know, that's something I noticed when I built my 12 Series Metro kit. I referenced A LOT of build threads and pics, and noticed that while most are great builds (well, ALL are great builds if the amp works perfectly!? :lol: ) the lead dress ran the gamut from absolutely straight with hard 90 degree turns to others being sort of "thrown together" with lead dress willy nilly, the classic rats' nest, and lots in between.

Being an artist by nature (painting, drawing, graphics... and then there's music!), I automatically notice the "hand of the artist" in someone's work. Be it a painting or an amp build. In the amp builds, you can see the "looming" of the lead dress, the hand of the builder (artist). I went through a lot of trouble to smooth out kinks and make mine appear to be flowing, but you can still see it as being overworked. :roll:

If you check out a lot of early, early Marshall builds, the first ones off the line (old blockheads etc) they're beautiful. Very technical, but also very natural dress. Not overdone. "Just enough and just right", I like to call it. THAT is what I noticed about George's hand on his Metropoulos amps. George really is the natural artist when it comes to these amps. It shows in the lead dress. The perfect balance between technically accurate and a natural flow and attention that comes from knowing what is "Just enough, and just right". Masterful.

I mean, they are works of art, right?

Alright, I'm done gushin'... guess that makes me a fan? :lol:
dave

wrea398
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Re: Late '68, early '69 restoration

Post by wrea398 » Sat Mar 26, 2011 1:16 pm

Pertaining to Georges restoration... what might this amp be worth in this restored condition. Aftermarket trannies, new wiring and completely restored board? Being that George did it could make it worth a few bucks more but I'm asking in general. I have a near identicle amp that need the same thing.

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white noise
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Re:

Post by white noise » Wed Jul 09, 2014 9:57 pm

VelvetGeorge wrote:Making progress on the reassembly.

Each part gets cleaned with solvent and a detailing brush before being reinstalled. I spent a lot of time cleaning the chassis too.


george
George,

Can you share what different solvents you use and if there are certain solvents you use on certain parts in your restorations and what you use for cleaning the chassis.

Very nice job, looks like new! :worthy:

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VelvetGeorge
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Re: Late '68, early '69 restoration

Post by VelvetGeorge » Thu Jul 10, 2014 2:03 pm

I try to use the least volatile chemical I can for each application. Usually nothing stronger than denatured alcohol. I clean the steel chassis, panels and transformers with alcohol on a rag, sometimes use a plastic bristle brush.
Aluminum does well with soapy water.
I apply light rust inhibitor to rusty parts of the chassis, and transformer laminations if necessary. I like Gibs, but any good stuff will work.

If the panels are removed I polish the front (side with no paint or ink) with Novus products.

Contacts, pots, switches, jacks and tube sockets get treated with DeoxIt.

Elbow grease always works better than using too many chemicals.

george
Check out Plexi Replicas for my personal amp builds...
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Matthews Guitars
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Re: Late '68, early '69 restoration

Post by Matthews Guitars » Thu Feb 25, 2021 9:40 pm

I know, this topic has been dead since 2014 but I'm working on a restoration of an essentially identical Plexi at this time.

Except...I got even less of the original amp than the subject of this topic.

The only thing I got more of was holes. The poor thing had been messed with so much that on the board, literally ONE component was original. And the chassis had many extra holes in it. How many? Rough estimate is 86.

Yes...86 extra holes in it.

The power tube socket holes had been so badly butchered when they were reamed out to take different sockets, that I made the big decision to strip the amp to a bare chassis and send it off to the local sheet metal shop for an in depth restoration.

86 holes were welded up, ground flush, and the chassis was re-galvanized and re-chromated. I have to confess that the sheet metal worker(s) who did the regrinding work didn't do the job to my expectations but....it's good enough. Not as flat and smooth as I'd hoped but functional

The octal socket holes were cut out to a standard size, new punchouts punched to fit, those were welded in and ground flush, and then the holes were remachined.

There are still a few "extra" holes but that's OK. This will never be a 100 point restoration.

Neither transformer was original or even correct. But the choke is! I think....

All new old stock tube sockets of correct types (Amphenol ceramic base, eye plates, spring clip rings) have been installed. I opted to rivet in four NOIS EBY TS103P01 9 pin shield base preamp tube sockets, and will make use of that socket for a gain mod.

The new OT for it is a M**en. The new PT for it is a correct type, more or less correct vintage used but good DET-4145H type. It's as close as I can get for anything resembling a reasonable price.

So, this topic is a great resource for me as I rebuild mine. And now I have a better idea of the probable build date range, as the serial number is lost. The back panel was diamondplate, and Marshall didn't start stamping the serial number into the chassis on the top surface near the input jack area until the early 70s. (They were definitely doing it by late 1973, but I don't know when they actually started doing that.

I make replica JMP metal face front and rear panels for various JMP era Marshalls. I'm not doing plexi panels yet but that's in the works. (Made to fit and be correct for Marshalls, and those that are feature-for-feature correct as far as the front and rear panels are concerned.)

This will hopefully get my first plexi restoration panels.

Things I want and need: Really all I'd like to find is a few of the tubular eyelets that are appropriate to the board type of this era. There are apparently a couple that are missing from my amp's board due to past mod work.

Oh... I forgot to mention the best thing about this amp as it was when I got it!

If you installed metal base power tubes like Tung-Sol or GE 6550s, the metal base would be energized at plate voltage when the amp was turned on! The previous "technician" who worked on that part of the amp elected to use the ground terminal on the tube socket as an HV tie point! What a clown! Well, it does keep people from stealing your power tubes. It's hard to be an effective thief when you're in convulsions on the ground!

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