Service manual

H/Z-100 Service Bulletins
FSB-MON-004: ZVM-135 Color Monitor w/Dark Vertical Band
If a dark vertical band, approx 1/2" wide, develops on the CRT's left edge, it may be
caused by the CRT's blanking signal. If this problem appears, perform the following
modification:
- Remove the 9-227 module and replace R3473 (3.9K) with a 10K resistor. Reinstall
the 9-227 module.
- Adjust for proper width and centering by filling the screen with characters, either
with the Z-100 monitor ROM Fill command or using a BASIC program, then:
-- Turn the G2 control up to view the retrace lines,
-- Adjust the width control until the black bar disappears to the left side,
-- Adjust the Centering until the right side of the screen pattern is on the screen,
otherwise 0% over-scan.
-- Turn the G2 control for normal viewing.
NOTE: Do this modification whenever a Toshiba CRT is replaced with a Zenith CRT.
--- Steve Vagts, Editor, "Z-100 LifeLine"
[e-mail]
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Copyright © 2003, Steven W. Vagts
Revised -- January 30, 2003
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