[TechAssist] Re: Toshiba 27A41 Intermittent Picture Distortion

  • From: "Christopher Barnak" <cbarnak@xxxxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Wed, 21 Jan 2004 09:14:38 -0500

I think the shadow mask is bad inside the picture tube. Especially when you 
mention purity problems.  Maybe  the auto deguasser, but I don't think so.
 
 
Christopher Barnak, CET
Norfolk Public Schools
School Plant Facilities
966 Bellmore Ave.
Norfolk, Va. 23504
 
Phone 757 628 3385
Fax      757 628 3392
cbarnak@xxxxxxxxxxxxx

>>> geminitv@xxxxxxxxxxxxxxxx 1/21/04 8:27:10 AM >>>

I currently have a Toshiba model 27A41 that has a very intermittent video
distortion that is rather hard to describe and unfortunately my digital
camera is at a different location. I will attempt to get it so I can
hopefully get a good picture of it and post it to my website later because
we all know a picture paints a thousand words in a case like this. I have
ONLY noticed this symptom on the RF input but have not yet determined if it
occurs using any of the video inputs (composite, component, or S-Video). I
am now running a DVD using composite video to see if it does occur there.
The best way I can describe the symptom is that first I do not notice any
audio problem at all, only the video (or raster) is affected. The picture
will get these vertical distortion lines like it is breaking up (no loss of
sync though) and at that time when this occurs, there are bands of purity
distortion that accompany the distortion. It can occur from a dead cold
start within a minute or the set can run for hours and then act up. I have
been all over the board with jewlers goggles and a jewelers loupe and can
find no cracks or bad solder. I cannot induce the symptom by tapping the
board nor by freezing or heating it. The symptom is completely random. So
far I have replaced the following components yet the symptom remains:

Tuner (TU001)
IC201
IC701
IC1501

So if someone has some suggestions, I am all ears.

Bob Waterman, CET® #RI-28
Master Technician License #9109
Service Manager / Parts Manager
Gemini Computer, TV, & Security Alarms
(508)695-7302
(508)695-7769 FAX
geminitv@xxxxxxxxxxxxxxxx 
geminitv@xxxxxxx 
www.geminicomputertvsecurityalarms.com 

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