[TechAssist] Re: GE 27GT614 CTC177BE grainy pix on some channels
- From: Philip Bader <tjanphyl@xxxxxxxxxxxxxxx>
- To: techassist@xxxxxxxxxxxxx
- Date: Thu, 29 May 2003 17:07:38 -0400
Dearest Dominic:
(how am I doing so far?)
With all that done to the set so far (T chip, tuner ckt parts,etc) you
no doubt need to do the DREADED tuner alignment procedure.Many things
have altered the circuit from it's original state (freq
response,etc)This requires a TAG-001 RCA generator that hooks up to the
coax input and generates all the cable channels while you monitor a pin
of the T chip for a voltage as you "jockey" the values up and down.I
understand you can use other brand of sig gens also. You may "fudge" and
try entering the service mode and plugging in some default values in the
tuner service menu from another CTC177 chassis.This may get you in the
ball park.But this is sort of like a garage using the settings of the
last car for your car's electronic front end alignment procedure.Either
way, once started you must go all the way to the end before exiting the
svc menu.
i tried to be gentle.
Lovingly,
Phil Bader
;-)
MDileo0000@xxxxxxx wrote:
>
> This set came in with grainy image on some channels. Off air low band seems
> okay. Channel 10 and 13 are almost snowy, quite grainy. Cable shows similar
> symptom on upper channels. The tuner wrap had already been done by another
> shop
> some time back and the chassis shows evidence of considerable resoldering
> outside the tuner area. My first thought was to closely inspect prior work
> hoping
> to find a solder bridge but no luck.
> I have changed U1001 T-Chip, U7301 mixer/oscillator IC and Q7102 VHF rf amp
> with no improvement. The voltage of the rf agc on pin 12 of U1001 is at 8 vdc
> when on ch 13, it should be 5vdc approx. Adjusting rf agc menu parameter
> makes no difference. Lifting pin 12 makes no difference. I get a snowy image
> without any antenna which seems to indicate good front end gain to me.
> Some kindness and soft spoken words would be most appreciated. Actually some
> useful tips would be better.
>
> Dominic DiLeo
> Atlantic TV
> Freeport, Maine
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--
Philip Bader
Jan Phyl TV Inc. (estab. 1976)
3420 Recker Hwy. Winter Haven, Fl. 33880
Fax (863) 299-8821
email: tjanphyl@xxxxxxxxxxxxxxx
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