The AM Forum

I recently discovered the RCH receiver was deaf and mute. The panel lights were on but dead as a door nail.

Pulling it out of the cabinet I saw the filaments glowing away. Hmmmmmmmmmm.

Once I got it out far enough the problem became obvious.

Ewueeee. Yucky.
Sorry; looks like a sticky case perp. for Nick Carter, master detective.  ;D
Well, temporarily, the power Transformer and choke are common enough.
Exact replacement might be tougher.
What baked it, filter cap. shot?

I haven't dug too deep yet, Rick, but a quick look at the filter cans show some intense bulging. I suspect they will be the suspects!

Most of the power transformers I've found with the right voltages have filament windings without enough scrote. I need 4 amps on both the 5 and 6.3V windings. Might have to go with separate transformers.

You might want to be sure and run the power iron to see if it has shorted turns or not... you can put the tar back in
the can, if the windings survived.

The other thing is that one can also put another transformer into the same can (assuming it fits) and re-pot it as well.

Something under 212F usually melts the tart nicely, gravity will drip it out, and the bottom of the can - if soldered - can be desoldered...

Good luck with the project...

                    _-_-

PS. really smart fellow whomever it was that cooked the rig long enough to melt out THAT MUCH tar!!

Well Bear, I usually leave my receivers on 24/7. So it could have happened during the day while at work or at night while asleep! Strangely there was no smell associated with this. My wife would have picked it up immediately. Fastest nose in the east!

Looking closer at it, it may be gunk from the choke. I'll know more this weekend.

Check out the myriad of other Scott receivers from that time frame. I suspect there's some commonality there. Saw a couple ratty RBOs on ebay over the last year for $9.99, good donors perhaps. They seldom bring much due to hefty shipping fees, but one was in Ohio so it might've been within driving distance.

Other possibility is Gary/WZ1M in Orono, ME. He can likely rewind it but may also have a spare kicking around.

Thanks Todd!

Autopsy showed the transformer is good. First choke is where the gunk is from and it is open. 2 of the 4 electrolytics are shorted. It looks like the choke croaked when the caps shorted. Resistance checks throughout the receiver are in line with the manual so I'm pretty sure a PS rebuild will fix it.
 

And a choke is a whole lot easier to replace or substitute.

Yes, I have one on order. 12hy, 250ma, 264 ohms. Should work just fine!
Pictures to follow....... someday!