Dangers of VPOS
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VPOS ADJUSTMENT ON COMPONENT INPUTS
Update on the VPOS issue:
A fellow Toshiba owner got his set fixed. A Toshiba service technician replaces
an EEPROM chip (part # 23905321-2). After replacement of the chip, all inputs,
including rf and composites which primarily are the ones directly affected by this, are
Note: The VPOS problem appears to be strictly a problem with the TN
series sets only.
QA02 Reset/VPOS Bulletin
You may want to read up on the QA02 reset also which may
be related to this.
Craig Schwabacher has some insight on the
potential for "ruining" your system by adjusting VPOS via the component inputs:
"The problem occurs when you enter the service mode while the Colorstream inputs
are active. In other words, let's say your DVD player is connected to the TV via component
video, and you're viewing a crosshatch pattern from the Avia DVD. If you enter service
mode while that pattern's on the screen (i.e., when the component video inputs are
active), scroll down to the VPOS parameter, and try to adjust it, nothing will happen ...
the onscreen pattern won't move and the VPOS hexadecimal values won't change.
When you cycle the power off and back on to exit service mode, the s-video inputs will
be screwed up...images displayed through them will almost look like a washed-out photo
negative. In my case, half of the screen looked like a photo negative, the other half was
black. From my experience, this problem doesn't occur when entering service mode and
adjusting VPOS from any of the other inputs (Video 1, Video 2, Video 3, or R/F). In other
words, once I figured out exactly what was causing the problem, I was able to successfully
adjust VPOS from non-Colorstream-HD inputs. Performing a QA02 reset fixed the s-video
problem, however, that also wipes out all of the service mode parameters and requires a
full service mode convergence. Not fun.
I'm not sure whether something actually has to be connected to the
Colorstream input to cause the problem. I think this problem is only an issue with the TN
series Toshiba sets (and not the TW sets)."
Reinforcing Word of Caution from ISF calibrator Mr Bob:
"Whatever you do, DO NOT UNDER ANY CIRCUMSTANCES order up
VPOS and hit Volume Up twice. If you do, kiss your S-video inputs bye-bye."
RESETTING TV AFTER A VPOS DISASTER
Tip from Zac: If you happen to lose composite
and s-video inputs because of inadvertently reset of VPOS, you can try the following
"If you do a reset you do it at your own risk. I will take no responsibility if
you lose your RF and composite inputs.
Enter the service mode and select any register item.
- Press and hold the RECALL button on the remote, then
- Press the CHANNEL button on the TV. The word RESET will appear in the bottom right
corner of the screen.
- Turn the TV off, then on. You will now have to re-enter some geometry and convergence
If you have your defaults/modified settings recorded somewhere, then you may be able to
recover. If not, you may need a service call.