Re: How to confirm a TV tuner is at fault?

Article View: sci.electronics.repair

Article #508

Back to sci.electronics.repair Previous Next

#508

From: dkuhajda
Date: Wed, 20 Jul 2005 16:59

24 lines
2427 bytes

Now that you are thinking about it.  The AGC voltage goes high to
increase the gain of the rf amplifiers inside the tuner to compensate
for a weak rf signal.  Most go as high as 9v DC.

If you unsolder the AGC pin off the tuner and feed a direct 4v DC to
it, you will probably find that the signal gets worse as the gain of
the rf amplifer is lower.

If the tuner is in fact tuning all channels correctly and it appears
they are locked on but just snowy.  Odds are very high that the problem
is in the rf stage of the tuner.

Do you have lightning where you live?
If that is a possibility, pull the tuner from the tv, carefully remove
the shields without prying on the internal parts of the tuner.
Visually inspect the front end (where the cable signal goes in).  Look
very carefully for any signs of burnt traces, arc marks, or bad solder
connections to the grounds.  Then do a good visual to the solder
connections to the pins of the tuner and the rest of the grounds.

Unless you have a tv tuner signal generator with if output, there is
little more you can do at your end beyond swapping out the tuner.

Instructor David

Technical Details

Message-ID: <1121878787.622523.184130@f14g2000cwb.googlegroups.com>

Path: arc1-ca.pugleaf.net!g2news1.google.com!postnews.google.com!f14g2000cwb.googlegroups.com!not-for-mail

References:

<1121692367.684276.178280@f14g2000cwb.googlegroups.com> <1121737563.005452.209730@g14g2000cwa.googlegroups.com> <1121845516.379519.281570@g47g2000cwa.googlegroups.com>

Show Full Headers

Complete Article Headers

X-Google-Thread: 1131b0,a749db4b04a371b9
X-Google-Thread: 103407,a749db4b04a371b9
X-Google-Attributes: gid1131b0,gid103407,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: arc1-ca.pugleaf.net!g2news1.google.com!postnews.google.com!f14g2000cwb.googlegroups.com!not-for-mail
From: dkuhajda@locl.net
Newsgroups: sci.electronics.repair,aus.electronics
Subject: Re: How to confirm a TV tuner is at fault?
Date: 20 Jul 2005 09:59:47 -0700
Organization: http://groups.google.com
Lines: 25
Message-ID: <1121878787.622523.184130@f14g2000cwb.googlegroups.com>
References: <1121692367.684276.178280@f14g2000cwb.googlegroups.com>
   <1121737563.005452.209730@g14g2000cwa.googlegroups.com>
   <1121845516.379519.281570@g47g2000cwa.googlegroups.com>
NNTP-Posting-Host: 166.90.91.150
Mime-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
X-Trace: posting.google.com 1121878793 18369 127.0.0.1 (20 Jul 2005 16:59:53 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Wed, 20 Jul 2005 16:59:53 +0000 (UTC)
In-Reply-To: <1121845516.379519.281570@g47g2000cwa.googlegroups.com>
User-Agent: G2/0.2
Complaints-To: groups-abuse@google.com
Injection-Info: f14g2000cwb.googlegroups.com; posting-host=166.90.91.150;
   posting-account=_3xaSAwAAAAmzT3yQtLkdnCSEay9zJty

Reply to Parent Message