My R-388 sprung a leak!!

[W1ATR]

I moved my 388 tonight to find a 3" puddle of clear syrup like goop on the table. (PCB's OH NO!!! Pack up the family, we need to evacuate immediately.!!!)

Upon further inspection, it appears it's actually dripping from the power tranny.

I didn't pull the tranny tonight, that'll be for another time, but has anyone encountered this kind of leakout before, and what did you do?

It looks like I may be able to reseal the tranny, but what do I refill it with? I do have a couple buckets of Shell Diala hanging around for a pole pig project, but I know the old stuff and the new stuff can't be mixed.

Thanks in advance guys.

[k4kyv]

It will probably run ok without filling it with anything.  If worse comes to worse, it should be a fairly standard receiver power transformer, and you should be able to easily find a suitable replacement.

[wb2fof]

I take it you already checked the circuit for shorts, with caps etc.

Bob, WB2FOF

[WBear2GCR]

How hot is the can running??

That's the question.

Melting potting compound is due to overheating. Either shorted turns or a load that looks a lot like a short...   

It's pretty specific to the R-388 and 51J series... but maybe a standard transformer can be shoehorned into the hole.

The plug in cap for the B+ in mine went south.  I made up a replacement with an octal socket, a pair of modern caps, and aluminum tube and some silicone rubber.

                _-_-bear

[flintstone mop]

I don't want to ruin this thread with a post outta no where, but it pertains to the problem of a hot transformer. Back in the 60's we had a nice tube stereo ampllifier from Knight Kit. The power amp was a KB-85, nice stereo tube amp on a chrome chassis, 4-EL37's in the center of the amp and 2-5AR4's for the 540vdc P.S. That power tranny was so hot you could not touch it. We had a small fan always blowing on it to keep it cooled down. I guess it was just its nature. It was a potted transformer and the stuff never ooozed out.

Fred

[W1ATR]

Thanks guys. Going to check it out maybe this weekend and see what it's specific problem is. I don't think it's heat related because I haven't used it in a while, and this is the first time I've seen it 'marking it's territory.'

I think these are oil filled cans anyway. Maybe it just leaked out, simple as that, but I'll take the previous advice and check for any overloading.

On edit: come to think of it, I had a choke in my 750 leak out once pretty much identical to this one. I just replaced it with a spare, and still have it in the junk closet. I have to look around and see if there's a suitable replacement for the PCB juice that's in these things. (Maybe I can save that hard to find TMC choke too.)

SK

[WBear2GCR]

It's oil filled??

Whooooo...

Ok, well if you can find the leak source, and drain the pupply, clean the leak, and plug it - either resolder, or maybe gastank epoxy? (gotta watch the fumes if you solder...), you can definitely refill with moderne transformer oil or mineral oil (almost as good).

I assumed it was a puddle of melted wax, not oil!?!??   

                     _-_-bear

[W1ATR]

Hi Bear. It's definitely not some kind of wax. It was a clear sticky liquid puddle   on the table and I looked inside and it tracks back to the tranny terminals.



 

[WA1GFZ]

Look at the terminals. They can leak if the seals dry out. Resolder it outside  if you need to. Most cans have a filler cap that is soldered after the transformer is filled with oil. Usually about 3/4 inch round plug. It faces upward on the top of the case. You can remove the cap with a large iron and drain out the oil if the terminal seals need repair. Just stay upwind of any fumes. Once the oil is drained out you can repair any leaks on seams or around mounting studs or inserts.
High temp solder with acid flux was usually used for this kind of stuff.