[TechAssist] Re: RCA, G27304DT, CTC177AM2, Tuner problem UPDATE

  • From: Doug Keller <dek@xxxxxxxxxxxxxx>
  • To: techassist@xxxxxxxxxxxxx
  • Date: Tue, 12 Oct 2004 06:35:35 -0400

Call Jeffery Dalmer and buy a spare finger.

Doug Keller
Wis-Kel Electronics
101 Freeland Ave.
Terra Alta, WV
USA        26764
dek@xxxxxxxxxxxxxx
dek@xxxxxxxxxxxxxxx
http://www.tech-assist.org
"Learn from the mistakes of others, because you
won't live long enough to make them all yourself"





daryls_tv@xxxxxxx wrote:

>Another day shot to Hell.....
>I spent all day again on this dog.
>It was mentioned several times to replace U7301.  This was the first par=
t I replaced to no avail.  I didn't have another new one to try but I had=
 the next best thing.  I had a working set to borrow parts from.  I repla=
ced the IC again but still no change.  Thanks to Barry Thompson for the f=
low chart.  I followed it out and found nothing wrong.  I compared voltag=
es to the working set and didn't find anything out of line.  I swapped ou=
t the varactor diodes without any help as well.  I figured I couldn't mes=
s it up any more than what it was... so I played around with the coils an=
d parameters.  Now I have some small gains but still not acceptable.  Cha=
nnel 2 has lines and motor boating.  Ch. 3 through 6 is acceptable but no=
t great.  Ch. 7 through 10 is good.  Ch.11 has no picture and sound, just=
 lines.  Ch. 12 through 18 are good.  Ch. 19 trough 22 are ugly with line=
s.  Ch. 23 through 39 are great.  Ch. 40 through 48 has poor picture with=
 lines and has noise in the sound.  Ch. 49
>  & 50 has nothing but motor boating. Ch. 51 up is great until Ch. 99 wh=
ich has lines and a poor picture.  That is the highest channel on the cab=
le system.
>I can still place my finger near some of the coils in the tuner and it w=
ill perk right up.
>Any other ideas would be appreciated.
>Thanks,
>Daryl
>Daryl's TV
>2402 Wyoming Ave.
>El Paso, TX  79903
>915-565-9184 Voice/Fax
>daryls_tv@xxxxxxx
>www.angelfire.com/tv2/daryls_tv
>
>----- Original Message -----
>From: daryls_tv@xxxxxxx
>Date: Sun, 10 Oct 2004 12:42:56 -0600
>To: TechAssist@xxxxxxxxxxxxx
>Subject: [TechAssist] RCA, G27304DT, CTC177AM2, Tuner problem
>
> =20
>
>>Hi,
>>This RCA, model # G27304DT, ch. CTC177AM2, is really kicking my behind.=

>>It started with the complaint from the customer of losing some channels=
 with lines in the picture.  I pulled it into the shop and did the usual =
tuner re-soldering job.  Set looked great and was delivered only to find =
out it was doing the same thing.  Took it back to the shop where it worke=
d great.  I re-soldered everything again plus all of the connections on t=
he smds.  Delivered it again and you guessed it...same thing.
>>The channels from 40 through 50 were either missing or full of lines or=
 motor boating.  I played with some of the tuner parameters and it seemed=
 to work but not to my satisfaction.  The customer was pleased, so I left=
=2E  A week later, same thing.
>>I pulled it back to the shop where it worked fine.  BTW... the customer=
 has another set that works fine on the same cable line.  I put an attenu=
ator on my cable line and the trouble showed up and even worse.  It gave =
me channels 2-6, 18-22, and 40-50 with the problems.  I re-soldered every=
 smd in the video section besides the tuner again and all of the grounds =
in the set... no help.  Looked with a high power magnifier for cracks in =
the print (none found).  Replaced IC7301, C7414(cracked), CR7102(didn't c=
heck the same as the others), Q7102(RF amp), U3201(eeprom), & U1001(t-chi=
p).  Did the tuner alignments after each parts change but still no joy.  =
I found that if I would place my finger over coils L7114 & L7112, the set=
 would start to function properly.  I got the same effect placing my fing=
er over L7115, L7113 & L7111.  I didn't have to touch the coils, just put=
 my finger near the coils.  This symptom reminds me of the old tube days =
when the grid neutralizer trimmer cap was
>>   =20
>>
>  o
> =20
>
>> ut of adjustment on the RF amp tube.
>>I really hope someone has encountered this and has a cure.... Help!!
>>Sorry for the long post but I deemed it necessary to explain the proble=
m.
>>Thanks,
>>Daryl
>>Daryl's TV
>>2402 Wyoming Ave.
>>El Paso, TX  79903
>>915-565-9184 Voice/Fax
>>daryls_tv@xxxxxxx
>>www.angelfire.com/tv2/daryls_tv
>>
>>
>>--=20
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>
>
>
>
>
> =20
>

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