[TechAssist] Re: Question Thomson technical help.
- From: "George" <grndmstrg@xxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 31 Dec 2001 04:26:53 -0800
Paul,
Does this chassis use a TDA7499 for the audio output? I do not have a print
for the CTC197 but if it uses the above IC check the small electrolytic
across the resistor to mute transistor collector (B+ source) controls the
mute on/off time, about 1 mfd. Also check the parts off pins 2, 4, 8, 9 and
10 as RCA uses separate voltage dividers to DC clamp the outputs (pins 2 &
4) and the closed loop gain circuit (pins 8 & 10) at common return point.
They all should have equal voltage reading at all the dividers (half of the
applied B+ 31v), check the resistors if off. Also check the electrolytic
(470 mfd) used for AC return of the gain loops used because they are
floating the DC return point. The 4.7 ohm resistors used at Pins 2 & 4 that
go to ground through a .1 mfd are critical in value. I used a CTC195 print
and a datasheet, it should be similar. What is the delay time of the pop
from turn on or off? That capacitor mentioned earlier might be bad. HTH
George
Afana Electronics
Moreno Valley, CA
----- Original Message -----
From: "Paul" <dntwntv@xxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Tuesday, December 30, 2003 6:12 PM
Subject: [TechAssist] Re: Question Thomson technical help.
> I have posted the problem and haven't come up with a fix. It is an RCA
ctc197A. There are apparently variations in this circuit because the
collector of the mute transistor Q11900 has a .84 ohm resistor to ground and
0 volts. If I lift that resistor I lose the sound. Other circuits show 31v
on the collector. The problem is a delayed loud pop in the sound when
plugged in and also when turned off. I have replaced the mute transistor and
a couple of caps in the supply for the sound. Several have tried to help and
I am not unappreciative, but maybe no one else has had this problem.
Paul
> "Phillip R. Hull" <phil245@xxxxxxxxxxxxx> wrote:You may be able to get
more help here. Whats the problem??
>
> Phillip R Hull STET
> phil245@xxxxxxxxxxxxx
> FAX 517--569-3075
> Professional Technicians only
> ----- Original Message -----
> From: "Paul"
> To:
> Sent: Tuesday, December 30, 2003 4:57 PM
> Subject: [TechAssist] Question Thomson technical help.
>
>
> > Have any of you used Thomson technical assistance recently? If so how
> would you rate it? Both AFS and non AFS. I have not called them in a
number
> of years,but the last time as I recall it was rather expensive and they
> didn't help with my problem. Paul
> >
> > Paul ,B
> Central TV&Video
> Grover Beach Ca.
> >
> >
>
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> Paul ,B
Central TV&Video
Grover Beach Ca.
>
>
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