Teak TV ctm687stcr vs TDA8305a readings

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Problem with grainy picture at TV and via VCR tuner only through RF.
Lots of tests done as previous posts but no change.
Anyone familiar with I/C TDA8305a, could you please look at these
readings and see what you can recommend:

pin 1 at 5.4     AGC take over - okai
pin 7 at 11.75v  supply voltage - okai
pin 5 at 7.84v  tuner AGC  (too high) -     should be 3.9 as per tv
schems
pin 18 at 11.18  AFC output(too high) - should be 6.28 as per tv schems
pin 19 at 4.29   AGC detection (too low)-   should be 6.18 as per tv
schems

Is there some relationship between these pins which could point to the
problem?
Thanks very much.
Al


Re: Teak TV ctm687stcr vs TDA8305a readings


finger to keyboard and composed:

Quoted text here. Click to load it

In a previous post you stated that you were able to watch VCR tapes
through the TV. Was this via the tuner or the AV inputs? If tuner,
then what were the voltages on the AGC and AFC pins? If normal, then
this would point to a weak tuner or weak antenna. Do you have a second
TV to compare?

FWIW, a datasheet for the TDA8305A is here:
 http://www.nteinc.com/specs/7000to7099/pdf/nte7047.pdf


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

Re: Teak TV ctm687stcr vs TDA8305a readings


Hello Franc,
Your comments have helped me understand the situation better and I have
performed more check with this results:
1-Picture from all channels from TV is grainy.
2-Picture from all channels from VCR's tuner via RF on TV is grainy.
3-Picture from playing VCR's tapes via RF on TV is good.
4-Picture from playing VCR's tapes via A\V inputs is also good.
Note:
When viewing the broadcast channels and the tapes via the VCR through
the TV's RF connector, the volts at pin 5 are lower down to 4.09v and
pin 18 down to 0.38v. However the broadcast channels look grainy but
the tapes look good.
When playing tapes via A\V inputs the volts at pin 5 lower even more to
.03v whilst pin 18 goes to 6.70v.
What do you think?
Al


Re: Teak TV ctm687stcr vs TDA8305a readings


Stop working on the tv set now.  What does the picture look like when
using the vcr as a tuner and the a/v inputs on the tv set.  The answer
to this question will confirm beyond a doubt that you have nothing
wrong with the tv set.

I think you have a weak cable signal going into your setup causing the
grainy picture and there is nothing wrong with the tv set.


Re: Teak TV ctm687stcr vs TDA8305a readings




snipped-for-privacy@locl.net wrote:
Quoted text here. Click to load it


Hi there, using the vcr as a tuner all channels also look grainy just
like watching the channells directly from TV.
Playing tapes always look good whether through the a/v or the RF
connector of the tv.
Al


Re: Teak TV ctm687stcr vs TDA8305a readings


Is it like this using the A/V inputs?
If yes, then you need to rule out the vcr as the source of the signal
problem.
If yes, then connect the cable signal directly to the tv set, bypass
everything else.
If the signal is still bad, then you have a problem with your incoming
cable.


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