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Beware of QA02 Reset

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Tip from Peter Schlosser:  Peter, a TW40X81 owner, decided to perform a QA02 reset on his set in an attempt to improve its picture quality.  Below is his account of the problems that followed:

"For reasons I will not go into in this post, I decided, today, to reset my unit, and key in the register settings.

I issued a QA02 reset, as outlined in the Service Manual. For those who are not aware, QA02 is the part number of the main memory, in which the unit's settings are stored.

To my surprise, it was rather painless. After the reset, all 290 registers already contained default values. I discovered that only about 40 of them needed to be restored to their pre-reset values. The rest of them already had the values corresponding with my notes.

The downside, however, is that I have lost tuner capability. S-Video & Component inputs are working, but cable tv is not. All attempts to restore it have failed, and Monday, I will call a service tech.

When thinking about the VPOS S-VIDEO bugaboo, described in other posts, I am thinking there is a relationship with my failure. You see, the cable was still hooked up to ANT 1 when I performed the reset. I am thinking this damaged something.

Self diagnostics is indicating a failure in blocks QV01 and QV01a. Accoring to the service manual, QV01 is the unit that funnels all the inputs from the back of the set into the various places inside the unit.

Until I understand what went wrong, and what is required to fix it, I am extending this caution:

Before performing a memory (QA02) reset, disconnect all inputs and outputs from the back of the set.

Well, I think I have really screwed things up. I have tried several resets, now, all with varying ideas attempting to restore the tuner. No go.

I have also discovered that the adjustment patterns in the Service Menu, the ones that show the cross-dot pattern, for adjusting HIT, WID, etc, will not display, either.

Another strange thing, when bit 1 is set in the OPT1 register, the audio from the tuner is restored, but no picture. Also, the Picture-In-Picture is working, for some strange reason.

All composite and S-video inputs are not functioning. Add this with the tuner (though, PIP, the secondary tuner does work) and the adjustment mode patterns in the Service Menu, and that leaves only one input that is working, the Composite Inputs.

I am pretty bummed.  I guess my QA02 reset has really fouled things up !!  Sigh. That'll teach me for carelessly tweaking."

QA02 Reset/VPOS Bulletin

Tip from by Stephen Smith:   "Here's part of a Toshiba technical bulletin that may (or may not) be relevant to the QA02 reset problem. The VPOS bug is a separate issue, but this may be relevant as to why QA02 reset works for some but not others.


Black picture after initializing or replacing memory IC.

Corrective Action:

QA02 should never be initialized. If replacement is required, QA02 must be replaced with a preprogrammed memory IC containing the proper data.

There are two different digital PC (UX01) versions and corresponding memory data used in the progressive scan DTV ready televisions. If the memory IC (QA02) is initialized or replaced with an improper replacement, the microprocessor can not communicate with the digital PC, resulting in a black picture.

The list on the following page shows the serial number ranges that have a version 1 digital PC. If a television's serial number is within one of the serial number ranges listed, replace QA02 with a version 1 memory IC. If the serial number is not in one of these ranges, use the version 2 memory IC.

All new replacement digital PC boards are version 2. When ordering the digital PC, order the version 2 memory IC if necessary.

Version 1 Serial # Ranges:

TN50X81 65990770 - 65992994, 98989055 - 98989664
TN55X81 65993500 - 65994004, 41994385 - 41995904, 98991895 - 98992204
TN61X81 41998430 - 41999239, 98000070 - 98999559
TW40X81 41441005 - 41441509, 98440000 - 98441734
TW65X81 98440890 - 98441294
TW56X81 98441295 - 98441599
TZ55X71 All are version 2

My TW56X81 falls into the version 1 serial number range, and I've done several QA02 resets w/o any problems. I'm not sure just what that means. Maybe if your serial number is not in the version 1 range, then QA02 reset will lose your inputs?"

Unless you really need to do the reset, you should stay away from this until more info is known.

If you have done this and found the "right way" of restoring the TV, please feel send us an email so that we can share it with other Tosh owners.


Tip from Louis Szablya:  Here's another thing you should be wary of.  Louis reports his experience below:

"I own a TW56X81 also but my serial number puts me in the Version 2 Range. I don't know if I did a QA02 reset or not but I have the exact same symptoms as Peter.

The reason I don't know if I did a QA02 reset is because I got to this sorry state by playing with my Pronto Remote. I decided to hack through the Toshiba IR codes and sent all 255 codes to the TV, one at a time, just to see what they did. Well it appears as if codes 168 and 191 (decimal) do a reset along the lines of the QA02 reset described.

I have gone back and checked every design parameter and even the ADDR registers and they all appear to be set to the appropriate values.

I have talked with a technician and it sounds like the QA02 EEPROM will need to be replaced."