Re: Electrohome G05-802 deflection board revision question

On Thu, 11 May 2000, Matthew Sell wrote:
>
> P500 on the schematic lists the "key" at position 5, while the board I have
> has the key at position 4.
>
> The foil diagram for issue 5 matches the actual layout for issue 2, except
> for pins 4 and 5.
>
> On issue 2, pins 4 and 5 are electrically connected, but the wire that
> connects to pin 4 is purple, and it runs to the CRT neck socket where it
> terminates since there is no CRT pin that make connection to it.
>
> Basically, the situation is that I have an "issue 2" deflection board for a
> monitor that seems to want an "issue 5" board. The immediate difference
> between the two (other than the obvious key change) seems to only affect a
> connection to the CRT that is electrically isolated.

I also have such a board, and it confuses the heck out of me. I did
the trick of "ignoring" the key, and while nothing was damaged, it
looked as though the monitor was attempting to paint the beam on the
surface of Mars, rather than the surface of the CRT, so I powered back
down and left it at that until I had a chance to take a closer look
at it, the wiring of the standard monitor, and the pinouts of a standard
deflection board.

In my case, I don't know whether the board was ever working; it had a
couple of fried parts that I replaced before I did the test. Obviously,
I'd rather not run it in the monitor for more than a few seconds until I
learn more about it.

Another interesting thing - the heatsinks on the preamp transistors are
in the same place, but are of a different physical form than the ones on
the "normal" deflection board.

Has anyone else ever seen a deflection board like this?

Later,
Doug.

-- 
 dougj   |
   @     |
hwcn.org |
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