On Wed, 17 Nov 2004 19:12:23 -0600, Rick Jones
put finger to keyboard and composed:

Franc Zabkar wrote:

I suggest you identify the vertical output IC or transistor pair. It
should be fairly obvious which IC is the right one by following the
yoke connector to the main PCB. These ICs are usually mounted on a
heatsink and are packaged in SIPs. Their supply is most often derived
from a winding on the flyback transformer. There will be a series
rectifier diode and probably a low ohm fusible resistor.

If you still can't find the vertical IC, post some part numbers and
someone will be able to recognise it. You will most probably find that
the datasheet for the IC will contain an application circuit that will
closely match the layout in your monitor.

OK, here's some info:

The monitor was manufactured by Toshiba; the name is etched into all
of the PCBs. The main board that lays flat across the bottom has what
appears to be P/N PW5253. This has one IC on it - a 42-pin DIP P/N
TA7644. I have tried to find a datasheet for this IC but no luck.
A second small PCB stands at the back of this and has P/N
PWPW5252-3. This board has all of the connectors for RGB, composite
video, split video and mono audio input for the built-in speaker. There
is one IC on this board, P/N TC4053.
The third board is mounted vertically on the right side (facing the
front of the tube). This PCB is P/N PW5252-1. There are 3 ICs on this
board - P/N HD7407, P/N TC4053 and P/N AN5352.
The 4th board in the system is the yoke board, which I guess we're
all pretty sure is no concern with this particular problem. Also, the 3
digital chips - 7407 and 4053 - would not seem to be of concern.
Research on the AN5352 IC showed it to be a character generator, which
seems odd for a monitor. This unit has no capabilities to function as a
terminal AFAIK.

AN5352 = NTE1835
http://www.nteinc.com/specs/1800to1899/NTE1835.html
http://www.nteinc.com/specs/1800to1899/pdf/nte1835.pdf

That leaves the TA7644, which I can find no detailed information on,
just general data that it's a monitor controller IC. Either the vertical
circuit is a part of this 42-pin chip or it's all generated discretely.

TA7644 = NTE1547
http://www.nteinc.com/specs/1500to1599/NTE1547.html
http://www.nteinc.com/specs/1500to1599/pdf/nte1547.pdf

This is the "jungle IC". Follow pin 26 (vertical drive output) to
either a vertical output IC, or to a heatsinked transistor pair.

FYI, you can search for datasheets of equivalent devices at this URL:
http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm


- Franc Zabkar
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