Mitsubishi VS55601 convergence question

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This set has poor dynamic convergence affecting two colors. (I don't
remember which two though). It is however fine around the center
area of the screen. I haven't been doing convergence repairs because
I got burned on a few in the past and had to cut my losses and walk
away from the job but with many 27" and even some 36" repairs
disappearing I don't want to keep turning this work down so I took
this one on. I pulled the convergence board and brought it to the
shop. It has 3 STK391-020's on it. I've never seen 3 STK's on a
convergence board before. I've always seen two. Whats the deal with
this configuration? I'm going to replace the chips and try to check
all the low value resistors on the board. The chips are cheap enough
and hopefully I'll be able to identify what the resistors are supposed
to be, but are there any special concerns I should be aware of before
reinstalling this board. I know that this work is where the money is
and I want to start doing more of these. Thanks for any assistance.
Lenny Stein, Barlen Electronics.

 

[Leonard Caillouet]

This set could have anything of several problems, and I would not assume
that the output ICs are bad. These ICs are two channel chips, where most of
the later ones are 3 channel chips. The set has a removable light box and I
would not try to service just the board. You need to make some checks with
the chassis intact to be able to run it. PITW to approach it any other way.

I'll send you an email so you have my address and can contact me directly.
I'll send you some tips.

Leonard