On 17 Jul 2005 05:17:30 -0700, "alitonto" put
finger to keyboard and composed:

I am repairing this Teac TV ctm687 which has a grainy picture on all
channels; even when using the vcr (however the tapes play a normal
picture.

Am I right in assuming that you are playing back tapes through the AV
inputs of your TV?

Hence I suspect the tuner (oscar 2900kkc) for which I measure 7.87
volts at the AGC pin which goes to i/c TDA8305A pin 5 which according
to TV schematics should only have 3.9 volts.

That could just mean that the AGC circuitry is cranking up the gain to
compensate for a weak or absent signal.

My B+ at the tuner is 12.11 and I wonder if this is the correct supply
voltage to the tuner.

This sounds typical.

Thanks in advance.
Al

I don't have any experience with your particular set, but here are
some general tips.

Check that the band switching pins (BU, BH, BL) respond to band
changes (UHF, VHF high, VHF low). Also check that the tuning voltage
(VT) increases and decreases smoothly as the channels are scanned.

See the bottom RH corner of this page for a typical pinout:
http://www.wagner.net.au/Catalogue/03_01.pdf


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.