Re: Weird G05 Problem, Please Help

Last night I was so convinced that I had found the problem, I
started humming the Superman tune (no, I have no clue why). It
turned out that with everything connected and hooked up, there
was in fact a short from the 2 heatsinks to ground.

What I came up with was D608 was bad and even Q606 (it must have
recently blown). Also, although it does blow the fuse F102,
the resistors still fry even if the fuse is not there. This
brings are list of once dead parts to: R610, Q606, D608, R613,
R618, Q605, Q603, R620. Its possible that the chasis transistors
are bad now, but I haven't pulled them to test.

Fwiw, I had pulled the bad D608 and was going to put D708 in its
place just to see if the vertical deflection would work, but I
forgot. When I powered it up, it blew the 2 fuses (no major fires).
When I put the diode from D708 in D608, the fires started back
up again. Any ideas?

Jon

At 05:53 PM 7/19/99 -0400, you wrote:
>At 04:00 PM 7/19/99 -0500, you wrote:
>>OK, let's walk through this. First you had "one visibly fried
>>resistor R610". I wouldn't think that could even happen, but
>>I suppose if R620 opened and the yoke kicked back through
>>it that R610 could get damaged, along with Q603.
>>
>>You then replaced "several dead components: R620, R610,
>>Q603, Q605". Well, there is Q603 and R620, and I can
>>believe the other two.
>>
>>Once fixed "R618 and R613 were killed with extreme prejudice".
>>Hmmm, acts like the heatsink (or any lead) of Q606 is shorted to
>>ground? Or Q607. Or a solder short on ANY of the replaced
>>parts.
>
>I tested both Q606 and Q607 out of circuit, but didn't look
>for a short. As far as a solder short might go, <is it
>getting hot in here or is it just me?> while trying to see
>why the board caught fire on me, I happened to flip the
>board over and see a little sliver of solder at one corner
>of the solder-side of the board (I don't think it was there
>when I fried the resistors, but anything is possible).
>When I barely touched the sliver, it fell on the ground,
>I may even have just breathed on it.
>
>>Another possibility is that either D606 or D607 opened.
>>This would crank all the currents up and cause just what
>>you have.
>
>I will check all of the diodes tonight including D606 and
>D607 and I will check the 2 transistors w/ the heat sinks
>for grounding issues. I'll let you know how it goes
>tomorrow. Thanks a *lot* for looking at this for me!
>
>Jon
>
>
Received on Tue Jul 20 08:38:06 1999