"Phil Allison" wrote in message
...

"Dave"

Have a very small (5" screen) black and white TV that has lost its
verticle hold.

** Verticle ???

Whatever...

It is not a faulty power transistor in the vertical output - or their
would be no pix at all.

Yeah, hadn't thought of it that way. See comments further down.

MIL would like it repaired if possible,

** MIL ?

Is there a fourth letter missing .....

Mother-In-Law. No fourth letter.


and kept in storage in case of another hurricane knocking out power and
services like the last one did. Upon opening it up I see a power
transistor (2SB834) with signs of overheating. My meter tells me that
the E/B and B/C pn junctions are switching at .574 and .572 volts,
respectively. Am I missing the mark, or does this sound a little low to
others as well, as if the pn junctions have been damaged?

** Sounds normal to me.

Its a few more minutes until my candy store opens, and several hours
before I'll be able to get by there, but to me, this transistor souinds
like a good candidate for replacement. Would appreciate hearing what
others think, if anyone cares to comment. Otherwise I'll bide my time
until I can prove the part one way or another. Just hope I don't have to
order the damn thing and wait a week.

** Loss of vertical HOLD is far more likely to be a fault in the small
signal circuitry OR the power supply.

Can you still adjust the vertical frequency to get the picture viewable -
but rolling ?


Yes, but the picture is only half the size of the screen at that point.
Attempts to adjust the vertical hold so as to enlarge the picture result if
more rolling. The 100K pot has to be maxed out to make it stop, and once it
is no longer totally maxed it starts rolling again. Thinking of stuffing
another 20K resistor in there to see if that changes anything...


The first thing to check is all the filter and coupling electros in the
vertical and PSU for the vertical.

You need an ESR meter or lotsa luck.

Guess I'll need lotsa luck. What does an ESR meter actually measure,
pray tell?

Thanks again. Have been running all day and am just now coming to the end
of it all.

Dave


.... Phil