W-G and Electrohome B-W XY variants

> One of the monitors is a little weird... there is a set of 4
> transistors which I've always seen mounted on a big heat sink. On of
> the monitors has these mounted in the metal frame!!! And this appears
> factory - not some Op who has lost the heatsink.
>
> Anyone seen one like this? Quite common over there?

Until recently, no. I believe this is the G05 variant described in
Atari manual TM-146.

A simple jig can be made to turn the 12-pin connector of an Asteroids
harness to the 6-pin and 7-pin connectors for input to the old-sk00l
Electrohome G05. With the jig, the monitor will run just fine in an
Asteroids or any other B/W XY game.

Seeing this thing made me wonder, though. Does anyone know what parts
can be swapped (with wiring harness mods in the monitor chassis) with a
standard (TM-151-style) G-05?

New-style G05: (looks a bit like W-G 6100 color X/Y layout)
1 - HV unit
1 - Deflection board, normal-style ("P299" board)
4 - Chassis-mounted deflection transistors

Old-style G05: (looks real weird as described in the original mail)
1 - HV unit (swappable with new-style G05 HV unit modulo pinouts?)
1 - Deflection board (totally different layout than "normal-style")
4 - Heatsink-mounted deflection transistors
1 - Low-voltage supply board with two heatsink-mounted transistors.
    Takes 30VAC in and turns it into +28VDC, much like the two power
    transistors of a W-G 6100 color monitor. There is no equivalent
    pair of power transistors on the TM-151-style G05 BW XY monitor.

Interestingly enough, I've also seen a variant of the "normal-style"
deflection board that isn't normal at all - it's got the same layout as
the TM-151 "normal P299-style" one, but a different pin is used for the
key on the connector that goes to the HV supply. I have *no* idea where
this thing came from or what it's supposed to be used in. Any ideas?

Finally, I've seen severe HV bloom on a 19" mono XY. The retrace lines
for the vectors are also visible. Replacing caps didn't work. Am I
correct in assuming that this indicates a problem with the HV diode?

Later,
Doug.

-- 
 dougj   |
   @     |
hwcn.org |
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