Zenith A50M84D Series, Service Manual

agmchas/p1

2-4

SERVICING - SMALL SIGNAL MODULE REPLACEMENT

SMALL SIGNAL (MAIN) MODULE REPLACEMENT

AND TOUCHUP CONVERGENCE

IMPORTANT

!

All convergence data is stored in

IC6002, the eight pin Serial EEPROM located
on the Micro Module. A complete re-conver-
gence will be required unless this data is

retrieved from the original module either by recording
the convergence values or transferring IC6002 to the
replacement module.

Small Signal Replacement Convergence Procedure

NOTE: If the small signal (Main) Module is the

cause of a Dead Set condition, and IC6002 is
faulty, the replacement module may require
a complete convergence setup.

If set still has on-screen display, use the following
procedure:

1. Remove shield from the Micro Module on the

original Small Signal Module and the replacement
module. Remove IC6002 from original module and
exchange it with

IC6002 from the replacement

module. Replace both shields making sure to re-
install IC6002 on DUD Module.

2. Press and hold

MENU

on remote until User Menu

display disappears. Then press

“999"

and

ENTER

.

Set will now be in the Geometry Adjustment Mode; it
is not necessary to save GEOMETRY settings. Press

FLASHBACK

to access the Green Convergence Sett -

ings. The left side of the bar describes the adjust-
ment name. The two numbers on the right side of
the bar are the Horizontal and Vertical settings:
Horizontal on the left and Vertical on the right.

Green Convergence Mode Display

3. Start by pressing

1

on remote.

Write down the

convergence values on the Digital Convergence
Numbers For Rear Projo TV sheet provided. Where
there are more than one set of numbers, press the
number again to see the second set.

4. After all the Green settings have been recorded,

press

MUTE

to access the Blue settings. Repeat

procedure and record all of the BLUE settings. When
BLUE is finished, press

SURF

for RED and record all of

the RED settings.

5. When all of the settings have been recorded, press

QUIT

to exit the Convergence Mode.

NOTE: REMEMBER - Avoid any mechanical adjust-

ments on the CRTs or adjustment of the
Horizontal and Vertical size controls on the
Power Supply Module, if only replacing the
Main Module.

6. Remove defective module and install replacement

module. Ensure that all connectors are plugged in
securely.

7. Place the set in the Convergence Mode and install all

of the convergence values. Start with Green and
follow with Red, then Blue.

NOTE: To save the convergence values just entered,

press QUIT. “Do You Want To Save The
Changes - YES/NO” will appear.  Use the
ADJUST button to select YES or NO, then press
ENTER to save.  Do this after each “Green,
Red, Blue” sequence to avoid losing all of
your work should a power interruption occur.

8. If, after installing all of the original values, set still

needs some touchup of the convergence, attach a
crosshatch generator to set and follow the procedure
provided. Use the small Left/Right arrows for hori-
zontal adjustments and the small Up/Down arrows
for vertical adjustments. Pressing

ENTER

lets you

toggle between the control’s stored setting and the
adjustment just made.

9. Access the Service Menu and enter the Stereo

coefficients as shown on the bar code label on small
signal Module.

Replacing Small
Signal Module

Dead Set

Record  convergence
values to worksheet

Proceed with
minor convergence

Transfer IC6002
from original
Module

Record convergence
values to worksheet

Install convergence
values or transfer
IC6002 to new
Module

Proceed with
minor convergence

Set has OSD Display