Triad HS-66 missing mounting studs. Workaround?

My business partner bought a pair of Triad HS-66 for some Pultec builds I'm doing for the studio.

I just picked them up and noticed the threaded mounting studs have been removed--ground off, or perhaps snapped off.

I'm trying to devise some sort of mounting strategy... I've considered zip ties through holes on the chassis, but that seems inelegant and unreliable.

Has anyone ever run into this situation and devised a workaround?

Maybe 2 long threaded rods and a strap across the top?

Or a thin aluminum strap going over the top, down the sides, and fastened to the chassis.

You could try bending one of the larger circular capacitor mounts into the shape of the transformer. Maybe a 1 and 1/4 or 1 and 1/2 diameter cap mount? Maybe larger, I don’t know. But that would be my first impulse.

Interesting ideas worth exploring! I mocked up a zip-tie solution and it's just not stable enough.

rackmonkey said:

You could try bending one of the larger circular capacitor mounts into the shape of the transformer. Maybe a 1 and 1/4 or 1 and 1/2 diameter cap mount? Maybe larger, I don’t know. But that would be my first impulse.

Click to expand...

This sounds interesting... I wonder, though, how I'd manage to attach the cap mount to the transformer? There are no tabs, holes or protrusions anywhere, save for the connection pins.

But something these ideas have me wondering... I wonder if there exists (or whether anyone could fabricate for me) a sort of metal "box" in which the transformer would snugly fit, but with mounting tabs on the sides? Then I could mount this box to the chassis with screws

per youngwhisk's suggestion.
bend a piece of steel plumbers tape up and over the HS-66,
cut to size,
solder 6-32 threaded rods to the tape, 
long screws will work, just cut off the heads,
clean the flux residue,
will hold the transformer more securely than the original studs.

soapfoot said:

This sounds interesting... I wonder, though, how I'd manage to attach the cap mount to the transformer? There are no tabs, holes or protrusions anywhere, save for the connection pins.

Click to expand...

Those capacitor mounts I’m talking about have a screw that tightens the mount around the capacitor. And they’re galvanized, which creates a high friction surface. So between the physical constriction supplied by the screw/nut and the friction supplied by the zinc coating, done with care you wouldn’t have to worry about the transformer moving around on you. Of course, you’d have to bend the mount pretty close to the same shape as the transformer to get these benefits. Any but minor gaps between the mount and the transformer can will reduce the effectiveness.

If you have access to a spot welder, lots of new and professional looking options open up to you. [EDIT: I’m not alluding to welding a galvanized cap mount here or anything else galvanized, as that creates poisonous fumes.]

Go look at Antique Electronic Supply to see the round cap mounts I’m talking about.

The capacitor mounting bracket is probably the easiest to try. I had a similar thought to the box idea. You could use a square aluminum tube a little bigger than the transformer cut to length. Mount the tube horizontally. Slide the transformer in. You could drill a hole in the tube and use a screw to push against the transformer like a set screw would. Secure the screw with jam nuts. Even better tap the hole and use a set screw.

If you really want it to be trick, you could make a PCB with mounting holes. The PCB could be the same footprint if you just insert low profile bolts before you solder it on. You could also add some female headers while your at it. Just make sure you clip the header pins flush on the back side to prevent them from making contact with the case. And leave a wire pad for a bit of bus wire to solder to the case to make your shield connection. Use a modified wire pad for the bolt holes so the bolts complete the shield connection. Getting the PCB perfectly flat will take care.

I would 3D-print a box in which the xfmr would fit snugly. Mounting is limited by your imagination. It may be necessary to print it in ABS, not in PLA if the ambient exceeds 60°C (140°F).

If you decide to go the inside-a-can route, for 25 bucks you can get a nice one with vintage style header on eBay. Surround the transformer with some open cell foam to keep it snug and you’re good to go:

https://groupdiy.com/index.php?topic=76784.0

Great ideas everyone!

Thanks so much.

It turns out I've used some Sowter transformers I had on hand and will reserve these for another project, but I'll very likely use one of these strategies when their time comes

I dunno if this will be of assistance:

https://groupdiy.com/index.php?topic=76933.0

and from that thread:

https://www.ironageaudioworks.com/3d-printed-brackets

HS-66 is listed, but it looks like he assumed the mounting studs (??)

Bri

Maybe you could drill holes where the studs were and then tap them. If that worked you could just use machine screws to mount it which would look good.

Would definitely be tricky, but might be worth a try.