DogP wrote:
Hey,

I had a post about a problem with a rear projection 24KHz RGB monitor
from a Waverunner arcade game (old topic was "50" Mitsubishi Rear
Projection Help"). Anyway, after looking at it, I noticed that it's
actually a Toshiba, but I'm unsure of the model (it's missing the back
panel where the model number should be). I'm starting a new topic as
the original problem appears to be solved, and this is more of a
specific problem now.

snip

Does anyone know why when I hit the adjust buttons, nothing happens?
Would it be something with the new resistor I put in, or would
something else be blown, or is there some sort of protect switch or
something? Searching the internet for Toshiba convergence problems
seems to pull up a lot about the output transistors on the convergence
board, would that make it unadjustable and way out of adjustment, and
would it seem possible that all three colors are not adjustable?

So far, I've tested all large transistors on the convergence board, and
none are shorted, and I've tested the outputs of the remote, and
they're good. Any other ideas of what to check?

Thanks,

Pat
Hi Pat,

This is a special 15-24Khz (CGA-EGA) Toshiba Monitor built for Video
Arcade Games I looked long and hard in our company archives and files
for the schematics but it looks like Toshiba never gave out copies when
we purchased these.

Start File Notes
Toshiba 50" Rear Projector Engine Model No:P-R502L

PCBs
VIDEO/CONV PB6101
HOZ/FLY PB6105
CONV-OUT PB6112-1
POWER PB6106

IC Information
Sanyo STK392-020 3-channel convergence correction amplifier (2pcs per
monitor)
HOD Tr 1MB12-140 INSULATED GATE BIPOLAR TRANSISTOR Fuji
Electric

To enter convergence mode.

Note: You need to have a working Game Raster input first

1/- Switch front panel convergence switch to on

2/- Press and hold TEST button for 5 seconds until convergence screen
is
up

3/- MODE switches between
- Center Convergence
- Line Convergence
- Point Convergence

4/- the four POSITION keys select what to adjust in Line & Point
Convergence Modes

5/- the four ADJUST keys will move the current selected Convergence
Mode

6/- the three keys R, G & B select and toggle on/off each color

7/- SELECT will switch between Game Raster input and Convergence Test

8/- NEVER-EVER press the RESET key.. all stored convergence data will
be
deleted from memory and you will have a horrible time just to get the
screen all squared up again.

9/- The WRITING key writes the current convergence data to memory. Do
this often as any power glitch can exit you from convergence mode and
you will loose all current settings you have made.

Convergence Tips

1/- Use Green as your base color.

2/- Square up the green grid

3/- use the point convergence to make all the vertical and horizontal
lines straight as possible.

4/- For Red & Blue, first use Center convergence to converge the center

of the screen, Red-to-Green & Blue-to-Green.

5/- Then Square up each color to match the green, Red-to-Green &
Blue-o-
Green.

6/- Finally use Point Convergence to get best overall convergence, Red-
to-Green & Blue-to-Green.

End File Notes


Your photos look like all the convergence data has be reset or lost so
you have a long job in front of you. I don't think that the convergence
amps are bad as all three guns are giving similar shaped pictures. Bad
Convergence amps usually show up as one or two colors badly or unevenly
distorted.

I start with Green only and use black electrical tape across the
monitor
front evenly spaced to the number of vertical and horizontal grid
lines.
Start with the horizontal first then the vertical. Once you have a good
green square grid, then adjust the other colors to match.

Wes.