Odd problem with SP-600

[w1vtp]

My SP-600 developed an odd problem over the weekend. When you first turn it on there no pilot lights and the AF output tube and driver fils do not light..  Well, I fuzt and tapped and nothing happened the all of a sudden, the pilots came on the the rx behaved OK

I have discovered that when I first turn it on - cold - there is no 6.3 volts right at the transformer (pins 15 & 16.  Sounds to me like there is an open in the 6.3 winding inside the transformer.  What I did to find that out was to let the rx cool down and put a Simp 260 right across pins 15, 16 and turn the rx on.  No pilots, no 6.3 volts - no 6V6 fils lighting.  Then I waited for about 4-5 minutes.  All of a sudden the pilots came on and there was 6.3 at the terminals of the xfmr.

Anyone ever heard of that?

Al

[WA1GFZ]

I bet the solder connection between the winding and output lead has broken inside the transformer.

[w1vtp]

I bet the solder connection between the winding and output lead has broken inside the transformer.

I bet you're right.  Anyone ever performed a lobotomy on a SP-600 pwr xmfr?

Comments?  I might just reheat the terminals with a big iron to see if it will reattach itself

Al

[WZ1M]

I think trying to reheat the terminals is the thing to do besides major surgery.
Gary

[WA1GFZ]

See if you can feed some flux in to get solder to flow.

[WQ9E]

Given potential damage to the transformer,  if applying heat to the terminal doesn't fix it I would be very tempted to mount a separate transformer for the filaments rather than go into the otherwise functional power transformer.  There should be plenty of room and a place to mount where you can share an existing hard point without having to drill any new holes.

Now hopefully your SP-600 isn't one that has the filter chokes potted with contaminated tar.  I won that little lottery and replaced them with Hammond chokes.

[w1vtp]

Given potential damage to the transformer,  if applying heat to the terminal doesn't fix it I would be very tempted to mount a separate transformer for the filaments rather than go into the otherwise functional power transformer.  There should be plenty of room and a place to mount where you can share an existing hard point without having to drill any new holes.

Now hopefully your SP-600 isn't one that has the filter chokes potted with contaminated tar.  I won that little lottery and replaced them with Hammond chokes.

OK Rodger

Yup -- agreed, that is a good option.  One of my friends out here who has had some experience with SP600s suggested that it might be as easy as putting some rosin on the terminal and reheating the whole thing.  The wire from the xfmr come out of the potting through a hole and wraps around the terminal. So that might be a good option.  I agree about not pushing my luck doing major surgery on an otherwise good transformer

Tnx, Al