CTV2003 04 10
Month of Issue:
TELEVISION TECHNICAL BULLETIN
Page 1 of 1
Sharp Electronics (UK) Limited
White – Carry out as required
Yellow – Carry out as required and whenever the unit comes in for service
Red – Carry out on all units
SYMPTOM RGB lines at top of screen / picture brightness ramps up to white screen or down to
A number of faults can cause the above symptom.
1. Corrupt NVM data.
2. Incorrect compensation of the RGB signal due to errors in the sense feedback
circuitry. This can be due to Q912 being leaky.
3. Incorrect setting of the screen control on the line output transformer.
Take action as required.
1. Reflash the NVM with the default data from this site – ensuring the correct data is
applied for the CRT type and Device permutations (see CTV 2002 04 01)
2. Replace Q912 with correct type (this is imperative)
3. Set up the screen setting (G2) as per the bulletin CTV2000 01 04
If Q912 gets hot during operation fit a 68
, 0.5W resistor on the print side of the PWB
between the collector and emitter of this device. Use part number VRD-RA2HD680J to
obtain the resistor.
Although Q912 may read correct, replacement is recommended where intermittent picture
problems have been reported.
The RGB lines at the top of the screen are a definite indicator of NVM corruption (unless
a clear frame foldover has occurred).
The picture brightness will appear to correct itself in service mode.
In some severe cases the RGB driver IC1801 may need to be replaced. As parts differ by
model number please use the service manual to verify part number (or parts listings from
the Sharp Technical Web site).