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Hitachi 53SWX12B - Red CRT out after DC chip replacement

3K views 5 replies 2 participants last post by  lcaillo 
#1 ·
1st, let me thank lcaillo and other wonderful folks on this forum for the wealth of information.

The convergence started going about a year ago, but would resolve itself after the set warmed up. The warm-up time gradually became longer. I started keeping the TV on all the time, and that worked for a while. Eventually, the convergence was out completely, and the picture became unwatchable.
I was ready to discard my 7-year-old HDTV, but this forum gave me hope.

After reading the threads, I ordered the Hitachi kit and replaced the DCCs with new Sanyo 394-160s. Two of the resistors on the conv. board were discolored, I replaced them as well. I checked the others with the ohmmeter.

After reinstalling the repaired board, I turned the set on.
The Blue and Green guns are working, but with a horribly distorted picture.
The Red gun is not working.

Unfortunately, I don't remember if the Red CRT went out before the convergence repair or not. I stopped using the TV several months ago when the picture became unwatchable.

Since I now have 2 issues, I am not sure how to proceed.

Any advise?
How can I verify if the Red CRT is OK?
Could something I did to the convergence board cause this?
One of the PCB traces broke off during the DC chip removal, I made a bridge connection, verified for continuity.
I am a bit afraid of messing with the CRT, given the voltages involved.

Thanks in advance!
LT
 
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#3 ·
The connections were checked and re-checked. I will re-re-check them.

The red crt is not producing output. The issue is: I am not sure it worked before the convergence chip repair.

I tried "jiggling" the circuit board attached to the bottom of the red crt, vigorously enough to bend the RF shield at the bottom of it.

Is there a way to check if the crt is working, perhaps by swapping the circuit boards between the red and the adjacent blue-or-green crt?

Any other suggestions?
 
#4 ·
It is hard to switch the crt boards because of the length of the wires, but that is one way to isolate the problem. Are the filaments lit in the neck of the CRT?
 
#5 ·
The filament does not appear to be lit.
To eliminate the recent convergence board repair as the culprit, I switched the blue and red connections to the conv. board. The no-red-CRT problem persisted, but the distorted picture was different.
So, the problem is possibly in the CRT tube, or the board at the bottom.

Not sure how to proceed, given the voltages present on the CRT.
LT
 
#6 ·
If the filament is not lit, that is the place to start. Find the connection for the filament voltage and work from there. Likely a cracked joint from moving things around or a connector displaced. Convergence failures have nothing to do with CRT filament voltages.
 
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