Hoffman 610 Lost B+

[zeno]

I cant see the schematic, too small & blurry. Also it is
laid out messy. Give a point to Sams for drawing all
schematics the same & with sense.

If something is loading down a source & the dropping
resistor is the right watts it should get real hot fast.
Measure ohms to GND from the source. If it reads say
5K look for anything that is fed with about 5K resistor.
Example if a 4.7K feeds the G-3 of a tube there is usually
a decoupling cap to ground that may short. Pulling
any tube using the source is another test.
Another place I found a few times was the tuner B+
feed-through shorted.
Good luck

73 Zeno

[Doug66]

I'm back in business, sort of. Before I acquired this set, the member I got it from warned me ahead of time that a mouse had been inside the cabinet on top of the chassis. The mouse had peed all over the IF board leaving that part of the chassis rusty and corroded.

I had tried cleaning that part of the chassis with various rust cleaners and steel wool. Either the mouse pee had corroded some of the tube sockets or maybe a combo of the steel wool and cleaners shorted something.

With everything connected, I would get an arch in certain tube sockets, and several 1K resistors fried. After replacing 4 tube sockets, my voltages are back to normal. However, I've lost vertical as my raster has come back to just a line. I'll start troubleshooting the vertical now then continue loking into why no signal is coming thru.

[old_coot88]

Originally Posted by Doug66

...I had tried cleaning that part of the chassis with various rust cleaners steel wool. Either the mouse pee had corroded some of the tube sockets or maybe a combo of the steel wool and cleaners shorted something.

Steel wool? Yeeikes!!

With everything connected, I would get an arch in certain tube sockets, and several 1K resistors fried.

[Joe Connor]

Ah, yes, steel wool. I learned my lesson back in the late 1950s when I cleaned my Lionel train tracks with steel wool and some of the fibers remained behind. A very interesting light show for a 7-year-old.

[Doug66]

Well after finding a replacement filter cap in the vertical section in which I had pushed it where the leads were touching (why I had no vertical), and another short; I am finally ready to post my 1str results on the screen.

I can't tune the signal in. The tuning slug doesn't get it any plainer than this. Tuner tubes and IF tubes have been subbed with no change. Sound is just a weak buzz.

Video IF voltages check ok.. I'll start checking other voltages next