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Dangers of VPOS

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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 fully operational.

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."


Tip from Zac:  If you happen to lose composite and s-video inputs because of inadvertently reset of VPOS, you can try the following procedure:

"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 parameters.

Good luck."

If you have your defaults/modified settings recorded somewhere, then you may be able to recover.  If not, you may need a service call.