Re: TECH: 13 inch Amplifone! HELP!!

In a message dated 9/26/99 10:10:17 PM, jwelser@ccwf.cc.utexas.edu writes:

<<
    This is WRONG (but sorta right, based upon that data that you were
given -- i.e. that te RGB inputs were disconnected.) If I understood
the original message right, the problem was that all the vectors were on
full brightness, including the retrace lines. A side effect of this is
that there is a very bright spot in the center, too. My PAT9000 has
EXACTLY the same problem. I saw it in a few "regular" Amplifones too.

    In the past, I found that cold solder joints on the two biggest
capacitors could cause this problem, but I tried that on mine and it
didn't clear it up, so obviously something else can cause it too. I
haven't had too much time to tinker around with it (too many projects
these days,) but I'll post my fix when I find it.

Joe >>

Yeah, All the vectors are on full bright. There is no RGB data getting to
the monitor, because those wires are not connected at all, anywhere.

I looked over a regular Amplifone board, and noticed that the RGB inputs from
the logic board, are connected to the three drive transistors (one for each
color). Each input is connected to it's transistor at the center pin. But,
on the 13 inch amplifone, the transistors have been moved to the neck board.
It seems that the center pins of all three drive transistors are tied
together and are all receiving the same signal.

I guess the next step would be to cut some traces and route the signal in the
same manner as the regular Amplifone board. I would sure like to know why
Atari decided to alter the monitor design, to eliminate the RGB inputs. Why
would they want you to have a B&W monitor with the brightness too high? It
looks like a factory mod, since I have to of the monitor boards for the 12
inch and they both have been modifed in the same way.

Scott
Received on Mon Sep 27 02:39:03 1999