[Jam_Master_J]

Having a weird issue with a Millet + tread combo I put together.

The tread powers up ok and measures a steady 27.00 VDC on the output, it is fed by a 24VAC transformer.

As soon as the millet is turned on, the transformer is wokring very hard, and the connection to the positive input of the tread gets very hot, even melting solder. For some reason the voltage regulator doesn't get hot though. The transformer got very hot so I didn't think it was a good idea to keep it on long enough to get any other measurements? The LED on the TREAD does decrease in brightness though, so it can't be sustaining 27V.

What should I be checking? It's one of the older Millet boards, I've completed the missing ground connections on IG and OG.

 

[Pars]

I'd start with the transformer connections... anytime a transformer runs hot like that something is wrong. A Millet should not load even a relatively small transformer. Anytime solder starts melting, something isn't right (which you knew

). Post pics/datasheet of the transformer, and pics of the tread.

 

[Jam_Master_J]

Thanks,
No data sheet, just a cheapie I bought at RS.
25VAC
Center-tapped secondary
50VA

Primary side has two black wires, I wired those to the black and white wires in a power cable. Secondary has yellow-black-yellow, I sent the two yellows to the input of the TREAD through a coaxial 5.5/2.5 jack. (transformer is on my desk, not in case)

This means that the -ve input to the TREAD is grounded to the case.

I just remembered something, when I had the TREAD outside the case, I was able to get everything setup in terms of adjusting tube bias and the transformer didn't freak out. Is grounding the -ve input to the TREAD to the case a bad idea?

 

[Pars]

Yeah, the AC leads (either one of them) are not the same as ground as far as your Millet or Tread are concerned. Isolate the jack.

Mouser has some nice isolated jacks (MisterX turned me onto them).

 

[Jam_Master_J]

Easy solution, I like it

I'll report back after some modifications.