Dynaco FM3 T72

[Peter Wieck]

I am looking for a T72 stereo discriminator can for a Dynaco FM3 - this is the short can that lives on the MPX board. The one in the unit I am restoring has a shattered slug that has divided into six (6) pieces that have molded themselves to the coil. I do not want to junk the entire beast if I can find that can elsewhere.

Please contact me at p f j w at a o l dot com - remove the spaces, etc.

Naturally, I will pay a reasonable cost + shipping.

Thanks in advance!

Peter Wieck
Melrose Park, PA

[John Robertson]

Any chance you can remove the old ferrite core chips, drill/carve out
the plastic core, and build a replacement thread?

I'm thinking along the lines of coring out the original threaded body
and using (perhaps) epoxy and a long threaded bolt of the same gauge,
liberally greased so it doesn't stick to the epoxy, to shape a
replacement threaded core.

Then find a suitable ferrite core...

John :-#)#

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[Peter Wieck]

On Saturday, April 18, 2020 at 10:55:05 AM UTC-4, John Robertson wrote:

> Any chance you can remove the old ferrite core chips, drill/carve out
> the plastic core, and build a replacement thread?

John:

I would engage at that level after I find a drop-in - which seems to have happened. I have often fabricated parts for equipment, and/or taken apart switches and so forth to make internal parts. I do keep a small stock of spring bronze and such along those lines. As to a ferrite core, If I can get the old one out cleanly, I will start along those lines surely. Note that the core is split into six vertical sections such that the alignment tool goes right through to the bottom without engaging. Dental-pick time once the can is out.

This particular FM3 had only one (1) virtue - a complete set of tubes and shields. The faceplate was filthy, the knobs crusted, the sheet-metal rusted and the boards covered with a hellish combination of nicotine and grease. Given what I paid for it - a dive into a dumpster - I figured I would keep it around for parts. Now that I am looking to fill the day, I have decided to give it a go for restoration, they are not making any more of them.

Cleaning took the full-monte - brake cleaner, ammonia spray and the dishwasher (x2). If I get it to behave properly, I will then deal with the sheet-metal.

I have gone through the alignment up to the stereo discriminator, it receives! So there is hope.

(PAM is a great release agent for the method you suggest - thank you for the idea!)

[John Robertson]

Don't a few of the surplus places have bags of ferrite cores?

Or am I thinking of the 60s...

[Michael Terrell]

Peter, can you find a similar transformer from another radio that isn't worth fixing? That circuit doesn't vary a lot, so the hardest part would finding one with the same form factor. I have extra cores, but I can't get to them right now. After the work is finished on my house to make it more handicap accessible, I will be able to get to them. If it doesn't slip my tired mind I will send you some.

[Peter Wieck]

Sorry for the unconscionable delay in this reply.

I have found a T72 from a fellow Dynaco fan, and it should arrive some time next week. Whereupon I will remove the bad one, clean it out, form a new thread if necessary - hopefully based on the original thread, and then send you the thread-former (Machine screw) for matching. Should I be able to get the old bits out without further damage, that is.

Wish me luck, and thanks for the offer!