310

This is one of the variants of the 133 internal structure.

 

Let's call this an early edition until I learn the proper name for it.

 

See how the case is a bit taller and narrow.

 

The issue I started to fix was a PTT hang up in the unit.

 

Seems there are two ways this happens.

A straight mechanical issue with the PTT switch.

 

Got this tip from N6CY

 

"The only think I did with my HM133 was to “flow” some rubbing alcohol into the PTT switch enclosure a couple of times while cycling the switch.

The mic still works, but maybe that was just a temporary fix."

 

This is very similar to the issue with this microphone.

It was hanging up in PTT.

Plus the caps were failed.

In this case the PTT switch had a mechanical failure in it.

Had to run solvent into the switch, then lubercate it with high quailiy mineral oil to keep it running.

 

The second is when the electrolytic caps (the silver parts) fail.

When that happens the electronics in the mic 'hang up' in PTT.

There are also hints of level shifting in the TX audio.

 

Anyhow, clean up the switch, solder in new caps, and the mics work properly.

 

Done