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Teak TV ctm687stcr vs TDA8305a readings

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

Reply to
alitonto
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On 26 Jul 2005 21:15:00 -0700, "alitonto" put finger to keyboard and composed:

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:

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- Franc Zabkar

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Reply to
Franc Zabkar

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
Reply to
alitonto

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.

Reply to
dkuhajda

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

Reply to
alitonto

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.

Reply to
dkuhajda

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