Toshiba 57H82 convergence ICs or other issue?

Greetings! I've read the wonderful "CRT based RPTV Convergence Repairs" sticky thread a couple of times and was hoping I could get a suggestion or tip on how best to proceed with my specific issue.

My 9 year old 57H82 recently had the green go way out of convergence. The symptom is that in the service mode convergence screen the green lines are very curved up at the bottom left (bowed up by several inches) and also curve up on the top right. The green lines up reasonably well at most other places (in particular in the center of the screen) and red and blue are fine everywhere.

When I run "Touch Focus" the lines for each colour move both horizontally and vertically (although the green lines are bowed as above, especially at the bottom left) and a "Touch Focus Error" is returned. If I manually try to adjust the convergence in service mode all the colours respond in both horizontal and vertical in most places; the exception is that the green doesn't seem to respond very well if I attempt to adjust points in the lower left of the screen where it's the worse.

From what I gather, the most likely problem is one of:

1. The convergence output ICs. Some places on the web stop there and say all such problems means you should change out the ICs and check/replace related resistors.
2. A blown/open/bad resistor or pico fuse near the convergence ICs.
3. Bad/aged solder joints.
4. The power supply to the convergence circuits.
5. The convergence generator circuit.
6. The green deflection yoke or green tube, etc.

I would have gone ahead and do the common convergence repair indicated by problem #1 but in the sticky thread it says:

If all of the adjustments for R,G,& B, both horizontal and vertical have an effect, your problem is somewhere other than the output ICs.

Click to expand...

Since I can adjust all those (except for at the problem area) does that mean that my ICs are probably not the (main) problem?


Am I correct that to test the resistors for #2 I need to remove the ICs or unsolder a leg of each resistor?


My brother is great with a soldering gun and repairs audio amplifiers and the like regularly. He went over all the solder joints for me, he said a few looked suspicious, but nothing changed after touching them up.


After reading the sticky thread about how convergence works I figured it was safe to do a quick diagnostic test for (unlikely) #6. I swapped the green and red sub-deflection yoke connections on the signal board and verified that when powered up the green lines were back to straight and the red lines where bowed out. That tells me everything after that connection is probably good with green.


So my main question is should I go ahead and try replacing the convergence ICs and check the resistors while they're out? From what I read I think I should replace the existing STK392-110 with STK392-150 if I do this.

Or should I look at something else first. What? The power to the convergence circuit? The inputs to the ICs? I understand the last involves checking for specific waveforms, can this last be done (just basically at least) with a scope without knowing exactly what the waveforms should be? Did I miss anything major/likely in my list above?

Thank you ahead of time for any helpful input!