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Ray Carlsen
 
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Rick Jones wrote:
I'm looking for a schematic for the above named monitor. My vertical
has compressed down to a thin line across the center of the screen.
Replacing the electrolytic capacitors has not helped.
Searches of the web have been fruitless. One monitor schematic for
the Commodore A2002 was alleged to be similar but when I get down to the
component level they are very different.


Rick,
You're quite correct about the A2002 schematic. I have both
monitors but no schematic for the 1080, unfortunately. However, I did
some digging inside my 1080 and the following info may help. This is now
on my site with a correction regarding the (dis)similiarity between
models. Sorry for the confusion.

It was made by Toshiba and
is unlike any other CBM monitor and my other schematics will not substitute.
Note that it is nearly identical in outward appearance and features to Commodore
monitor models 1902 (non-A model) and 1084. However, the internal construction,
components and board numbers are completely different. I own a 1080, and I have
collected some information about it to assist those who might have to repair
one. The chassis number of my monitor is TAK8520. Although the construction of
this monitor makes troubleshooting difficult because of crowded boards, all
boards are silkscreened on both sides with component identifier numbers. All
internal controls are marked as well.
Note that each section of the monitor is numbered, and that can be used to
locate components in each circuit. The following is viewed facing the rear of
the monitor with the back cover removed. The bottom main PC board contains the
Horizontal Sweep, HV, Vertical and low voltage power supply circuits. The PC
board designation for the H sweep section is 400 (example: H output transistor
is Q404). The vertical sweep section is designated 300. The power supply is 800.
The left upright mounted PC board is analog video and digital signal
processing (100) and an audio amplifier (600). That board swings away to the
left (remove two screws) for better access to it and the bottom board.
The rear upright PC board is an A/V and RGB connector interface and has
both 100 (signal) and 600 (audio) components on it.
Lastly, the CRT board (500) mounted on the back of the picture tube
contains the driver and output transistors for the CRT.

The Low Voltage Power Supply (LVPS): main switcher transistor is Q801, a
2SD1432. The line fuse is a 3 Amp F801, and the B+ fuse is a 1.2 Amp F802.
Both fuses are on the bottom PC board in fuse clips.

HV & Horiz Sweep: the Horizontal Output (Line Output) transistor is a 2SD1427 Q404
and the flyback (line output transformer) T461 is part number TFB5017AD (which
looks like a Panasonic number).

Vertical circuit: this monitor uses descrete components (no ICs). The output
transistors are Q304 2SC2073 and Q305 2SA940. Note that this monitor has a
service switch in the center of the bottom board towards the left side. That
switch should be in the NORMAL position. If in SERVICE, the vertical sweep
will collapse to a single horizontal line (used for CRT setup adjustments).


Ray