[TechAssist] Fw: Toshiba CF-315
- From: "fantaj" <fantaj@xxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Sun, 30 Sep 2001 15:20:27 -0400
Toshiba, CF315,
an old classic, similar to this circuit are CF915, CF917,
Symptoms, turn the set on, chanel 2 comes on, set totally out
of
sync, looks more like the horizontal, as soon as you press the channel up or
down buttons, the screen gets dark, sound disappears, and the channel
numbers
start running, like bad AFT, once ina while,AT RANDOM, it locks to a
station,
sound comes on, but the video totally out of sync again.
this thing has a video amp
Q201, I have good video waveform there, then the video goes thru a cap C301,
and feeds to pin 57 of the jungle TA7777, thru a 300 ohm resistor, here is
the strange thing, at this end of the 300 ohms, I have perfect video, the
other end to pin 57, the sync input, sam calls out about 1.5VPP, which I
have
more than that this side,but at pin 57, that is almost a flat line, just
millivolts of video.!!!!!!!! Either sam is wrong, which I don't beleive it
is, but what's going on, check/replaced all parts around that area, isolated
sections, in total dispair, I replaced the TA7777, almost sure that was not
the problem, ONE TRACK MIND, no matter, always the same! The AFC pulse from
the flyback is perfect, pin 59, and looks ok on frequency, , there is not
much left, I will try subbing the 503KHZ resonator today, and see what
happens, in case I did have an AFT problem, carefully tweaked the aft coil,
ended up subbing the whole coil, as I have one new, that I use for test
purposes, no help.
Anyway, I am at my wits end, today, I am going to use my
tuner
subber, see if the tuner control has a problem, if that fails, will, give it
back I guess, let someone else give it a try.
Please any Help greatly appreciated.
fuzzzzzz
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