Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Viewsonic VG150 --"Common" failures FOUND and a request

I have five of these that developed the same problem after about 3
years. In DOS mode or when entering a PCs BIOS setup, the bottom 1/3
of the screen went blank. If a line of text on-screen fell in just
the right place, the bottom line of dots of the letters in that line
would "echo" down the screen.

Following a long, frustrating website search for others with the
problem, I found a news forum post on a German website that listed a
bunch of capacitors. I could barely make out the translation ("Is the
smoke out yet?") but gathered enough information from the post to
determine that it had some relation to my problem.

I ended up changing ALL of the electrolytic surface-mount caps (not
too bad, only 18) and the one non-polarized 10uF/50V regular
electrolytic on the PC board. That restored the first one. I then
noted that, on the next two, one part value had been changed for C104
when the monitors went back for "repair" to Viewsonic previously--from
an original value of 22uF to 2.2 uF. From what I could determine
none of the other part values (caps, resistors) around that cap had
been changed. Changing the cap to the original value of 22uF caused
the display to be blown out vertically--an ATI graphics card logo on
PC boot-up would be at both the top and bottom of the screen. Changing
it back to 2.2 uF brought it back in, but the screen was still a
little "larger" than it should be. Also, the picture was shifted a
bit to the left.

The third monitor still seems to have a dead spot, but it's shrunken
from 1/3 of the screen to about 1/8th. I should note that the "dead"
zone is only in DOS; in windows everything appears correct.

So now I'm at this point: I know that Viewsonic uses a "special" cable
and software that allows tweaking and adjustment of internal monitor
controls. I need to acquire those. All the monitors cost me less
than $100.00, and each is worth squat due to depreciation. I can't
spend $2-300 on those pieces.

I know the cable can't be a mystery--SOMEONE has had to have built
their own. The software...well, it's got to be available for
downloading from SOMEWHERE. I once found a site listing "Viewsonic
Service Adjustment Disk" a while back, inviting people to send an
email and promising the software would be sent but I never got an

Can anyone help me find a cable schematic and the proper adjustment
** To respond, remove the crap from my addy... **
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