RS to TAG retro fit.

[908ssp]

I figured I'd show this you might find it interesting. Just a totally geek thing to do but a little touch among many to make a cooler Offset clone. When I got my Marstran RS I had already given it a lot of thought and someone sent me a picture that someone else had already done it so I wasn't the first but I did think of it and do it on my own. Anyway I made the little tag board to match the RS OT. I noticed in some of the Marshall chassis's they had two holes like I did and some were just hacked out and ragged. Not at all sure what was the deal at Marshall or if it the ragged holes were done later. But since I could do the neat holes and they were stronger I did that. The steel end caps to the transformer was removed and trimmed away and the edges were touched up so they don't rust right away. The rest you can see in the pictures.

[OnTheFritz]

Hey, that's really cool!
I've never used an RS clone OT, but thought the tag arrangement would be much *cleaner* to work with when changing impedance's/primary's etc.

[S.Marshall]

I see we're thinking alike on the offsets. I'm doing my OT the same way. Way cool.

[shakti]

Most excellent suggestion! I am probably going to do a block logo JTM45 next, I have the Marstran RS OT for it, but this looks so much neater, and as you all say; much easier to work with once it's done.

[Joe Popp]

Man what an awesome mod! Very cool!

[electricskychurch]

how did you do the cutouts ?

i have an original RS Deluxe OT and plan to build a 65' jtm45 block logo clone but i'm still wondering how i will make the cutouts ! LOL

somebody on the forum (S.Marsahll) told me about dremel tools but i would prefered to have it done before i buy it ( i will certainly buy a metroamp kit) ! LOL

[908ssp]

I did mine on a milling machine I own. Marshall didn't do them that nice on many of the Offset amps I have pictures of they just hack a big rectangular hole in the chassis. I couldn't see doing it that way in one picture it is done with two holes. Pictures not the best but this one is very original many Offsets have been repaired over the years so many of the original components are long gone.

[neikeel]

That's very neat.

Did you peg the baord to stop it slipping or did simply tightening the tranny clamp it down tight enough?

[908ssp]

Yes the clamping of the transformer clamps the board in place. I had to select just the right size washer so that there is a minimum of clamping force so the transformer feet weren't distorted or under too much stress. Plus that is a lot of wires so they help hold it as well.

Hey Neil see those gray caps in the picture above? I was told that those are the authentic caps for an Offset and that Mustards are all replacements as those caps were paper oil and didn't last very long so you hardly ever see them. Does that sound plausible to you?

[chubs]

Alex, Can you give me the dimensions of the cut outs I'm thinking of going this route too... Thanks in advance.

Chubs

[neikeel]

Yes the clamping of the transformer clamps the board in place. I had to select just the right size washer so that there is a minimum of clamping force so the transformer feet weren't distorted or under too much stress. Plus that is a lot of wires so they help hold it as well.

Hey Neil see those gray caps in the picture above? I was told that those are the authentic caps for an Offset and that Mustards are all replacements as those caps were paper oil and didn't last very long so you hardly ever see them. Does that sound plausible to you?

I think that for Marshalls of this era you know at least as much as I do .

Most of the early Marshall stuff was ex-WD surplus, some of it high quality, picked up by Bran and Marshall as it was available. I suspect the grey ones you see there were correct, particularly in the prototype era (I have seen these on other early Marshalls) mustards are consistent 63 onwards.

Marshalls were never squeamish about using any make of component in a crisis either (RS/WIMA etc).

I am surprised that Marshallhead from Scotland has not chipped in as I know that he is building/restoring one of these at the moment.

[908ssp]

Alex, Can you give me the dimensions of the cut outs I'm thinking of going this route too... Thanks in advance.

Chubs

I'll see if I can find my sketch if not I'll have to pull the chassis to measure that might take a couple days. I made the TAG board first and then cut the holes to fit. I made the holes as small as possible to keep as much strength in the chassis as possible but I am not sure how wise that was. A little extra space would make locating the holes a lot easier mine are pretty close to the turrets. I even had to wrap the output wires from the inside out to maximize clearance.

[chubs]

I might go as big as I can in that case... I'll be using autocad and getting the chassis laser punched... Thank!

[Puerco]

Did you consider, since the pegboard is only clamped between the OT and the chassis that under the influence of vibration, moving around and warming up/cooling down cycles the pegboard might move a little and one of the turrets might touch the chassis and cause a short? You've done such a great job, it would be horible if such a thing would happen...

[908ssp]

Yes I considered it and came to the conclusion that there is enough tension and weight from the OT that it won't move. You will notice I used flat washers on top and bottom and nyloc nuts to hold it all in place. I guess you could put a spot of glue between the transformer leaves and the tag board if it made you more comfortable.