Metropoulos Forum

I have ordered my 50W board and other parts and am looking forward to starting my project.

Issue: the 50 watt Marshall (if I am not mistaken) uses 3 multi-caps. I saw that the chassis used in the kits has circular cuts for mounting the multi-caps. My chassis only has one multi-cap mounted below the deck, and its mounted off to one side (not between the transformers as the Marshalls appear to be).

How do you guys recommend addressing this issue? Do I have to take the chassis to a metal shop to get two additional circular holes cut in the chassis (or perhaps 3 so the holes are in the same location as on the Marshalls)? Is there another way to mount the caps?

Thanks,
Scott

For safety's sake I'd ad holes so the leads are down inside the chassis. You COULD mount them upside-down with the clamp so the leads are sticking up and then you'd just drill holes, but I'd be scared to death to reach in there.....might work better this way if there's room inside the chassis to mount them, like an old JTM45.
But why cough up dough to go to a machine shop? Go to Sears or wherever and buy a Greenlee cutter in the right size and do them yourself....and you'll always have the tool for the next time around....

The upside down mounting sounds a bit hairball, with the wires having to travel "up" the side of the can to reach the lead. I think drilling/cutting the holes sounds like the better way to go.

Also, is a "Greenlee" cutter something that attaches to a drill for cutting metal? So I just go to Sears and get the size I need - what size is that if anyone knows?

And, if I cut the chassis, I can mount all the caps in the equivalent position that they occupy on the Marshall, for ease of wiring.

Scott

A Greenlee cutter is actually more of a punch. You'll have to drill a hole big enough for the center bolt of the cutter. The cutter is in two halves that you assemble on the bolt, then as you tighten the bolt the cutter pulls through and makes the hole. It will come out way neater than the holesaw you've got in mind.
It's a good investment, because I'm with you on the idea of running the leads up the side of the can with the terminals on top. One wrong move and you're fried.....
Here's an example of a Greenlee cutter:
http://www.grainger.com/Grainger/produc ... 70&ccitem=
I just wish it was pictured spaced apart so you could see how the cutting half looks, it's kinda got two big "teeth" 180 degrees apart that slide into the other half as you tighten it up.

OK, I understand now. Do you know offhand what size hole I need to cut; or what size punch I would need?

Thanks much.

You can mount the caps inside without drilling a large hole like this:

Far right, mounted over the power trans.

George

Interesting. But I have two additional caps to deal with. I'll have to check on whether I have enough room inside to mount the two additional caps.

That amp in the picture, where are the other caps? I think I see the bottom of one near the upper right hand corner.

There are just the two can caps. Four stages of 32uf filtering.
That's a JTM 45 pictured.

George

Is that the way JTM 45s were factory wired - with one cap below (or above, depending on orientation) and one cap inside the amp?

Sems like often times there was one of the filter caps in the middle of the turret board, but there was usually one mounted to the side of the chassis like that. That's what I meant about old JTM45's above, if you've got the room it's a good option.

Cool - I appreciate the help guys.

Im gonna tell you a little secret, if you have an aluminum chassis you can use a regular spade bit, the ones for wood. aluminum is very similar to wood as far as metals go. You can buy a punch kit over at harbor freight for $20, but the spade bit is cheaper and faster, and available at any hardware store.
i have done this many times and the holes are very clean..
mike