Re: G05-802 TIS98 cross reference

kevinpmullins@xxxxxxxxx wrote:
Progress made.... sorta.....

Not finding anything jumping out at me as being wrong or bad, I took
the chance and removed D504 (the LED) in order to temporarily bypass
the spot killer and turn it on JUST long enough to get a visual of
what's going on. (I know, I know)
But the brief glimpse was enough for me to see it indeed had a failure
on the Y axis. Horizontal vectoring, but no vertical.
So now I at least knew which side of the deflection board to
concentrate on. (all the 600 numbered components)
As I'm pulling legs up and measuring resistors, diodes and such I
noticed a spot of old flux from a previous reflow on pin 6 at P600
that just didn't look right. So I clean it off a bit and
whatdayaknow..... a totally burnt trace to that pin.
So I repair the trace and hope for the best.......
Well, that's when things went nuts again. Sure it did something
different all right.
Burned up R608, R613, R605 immediately.
Guess I'll have to back track a little more and look at Q607 and the
rest of that circuit and see what's going on.



You should be able to bypass the spot killer by cranking up the brightness, at least that works on the color vectors, not sure offhand if the G05 has enough range.

If parts burned up then you have a short. Did you check both junctions of all the transistors with the diode check on a multimeter? Do you have horizontal deflection all the way across the screen, or do you have just a flat line or a quadrant of the screen with something resembling a normal image? Double check that the correct chassis transistors are installed in the correct sockets, that the wiring is all intact, none shorted to the frame. For that trace to burn, you'd almost have to have a shorted chassis transistor. I would also look at D608 and Q607, as well as Q606 and Q605. You may want to disconnect P600 and take measurements with power applied. Q605 and Q606 are almost certainly shorted at this point.

Such is the nature of power electronics that failures often cascade. You can fix 99% of the problem but miss one bad part and everything blows up again when you apply power. I've got in the habit of very carefully checking and double checking everything, particularly when expensive or hard to find components are involved. For line powered items I sometimes wire an incandescent lightbulb in series with B+. You could probably do something similar with this, put a pair of 10-20W automotive bulbs (or a single 24V bulb) in series with each side of the AC input.
.

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