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Zenith ZB4683RK convergence problem

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Joined: 07 Jan 2006
Posts: 1
Location: tn

PostPosted: Sat Jan 07, 2006 9:42 pm    Post subject: Zenith ZB4683RK convergence problem Reply with quote

Hello, If you look at the pics at
you will see what I see on this TV. The customer convergence controls
on the front of the set act as follows:
Red left-right doesn't move the cross hatch pattern.
Red up-down doesn't move the cross hatch pattern.
Blue left right does move the pattern
Blue up-down has no affect on the pattern.
The cross hatch pattern was generated by an old HealthKit color bar

I replaced op-amp IC4003 and two 100 ohm resistors in its power supply legs.
The resistors had dropped to around 50 ohms.
Checked all of the pnp/npn output transistor pairs. They look good.

Went around looking at the bases, collector & emitters of transistors on the
board. Did not see anything that called out for closer inspection.

I have a scope and have looked at some of the points on the convergence
board. Not knowing exactly what I'm looking for I have some questions.
Shouldn't the general shape of the horizontal signal applied to each of the red,
green and blue coils be similar? If you inspect
waveform5.bmp through waveform10.bmp at the above web site you'll see some of the waveforms that are applied to
the trailer yokes. I looked at the vertical and horizontal signals coming in
to the convergence board, they look good.

I have measured the power supplies, the + 16 and - 16, and +,-12 and +,-7 are all close.
I can post on my web site captured waveforms at points in the set.
Oh yes the schematics I have are more general artistic renderings instead of actual circuit diagrams.

Any ideas of what components I should look at? I hesitate to purchase a
replacement module for fear I would be throwing good money after bad. I fixed a power supply module
earlier only to have this convergence problem pop up after a few months.

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PostPosted: Sat Jan 14, 2006 7:25 am    Post subject: Reply with quote


Has anyone looked at the waveforms on my web site? Is that a good
idea to post waveforms to help in trouble shooting?

Please some feedback, please.
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