THORN 8800 CHASSIS

This set has been troubled with the same problems from
new. The symptoms are that the red content of the picture
changes to mauve, followed by total loss of colour, and
when changing channels the picture appears in
monochrome for three-four seconds before colour appears.
Adjusting the set oscillator frequency control R210 and
trimmer C188, both associated with IC5, seems to make no
difference. IC5 (SC9506/TBA395) has been replaced.
Some batches of TBA395 i.c.s were suspect for thermal
effects, but since this’ item has been replaced and the
symptoms remain it seems clear of suspicion. We suggest
you replace the crystal and the two electrolytics C186
(6.8µF) and C187 (1µF) associated with R210. It’s not
beyond possibility that the following SN76227
demodulator/PAL switch/matrixing i.c. (IC4) is faulty.