Toshiba TV CF3266a

[Charlie Bress]

My son's future father-in-law just gave him a Toshiba CF3266a set that had
been replaced. This old TV has been losing vertical amplitude and
adjustments were no longer able to restore the size. I have not seen this
set yet , but have been invited to try fixing it.

My understanding is that picture shrink had been from both top and bottom.
I am betting it is a cap or two that have degraded. This box is a 1991
build. Are there any particular suspects in the vertical amp section.

I am also hoping that the suspects are PTH and not surface mounted. I have
no way of checking caps other than a VOM to check for leakage and plain old
substitution if I can find suitable replacements.

I am well aware of HV concerns and will keep my fingers away from places
that bite.

Charlie

 

[sofie]

Charlie Bress:
When you are not too busy filming CSI Las Vegas you should do a google
groups archive search for "Toshiba vertical"..... you will find dozens of
good hits that will most likely pinpoint the problem to dry, leaky, high
ESR, or otherwise faulty electrolytics in the vertical deflection
circuitry..... this has been a very frequent repair topic on this
newsgroup for many years..... so there will be lots of archived posts to
read and to learn from. Also you should go to the website for this
newsgroup at
http://www.repairfaq.org/
there with some searching you will find specific repair hints and important
safety information so if you attempt to repair the television yourself you
can avoid the dangerous and lethal electrical shock hazards.... note that
these hazards can still be present even when the television is disconnected
from the AC power.... be careful.
If after reading through the repairfaq and other google archive information
you are still not certain how to proceed then you should at the very least
TAKE it to a repair shop for a repair cost estimate so you can make an
intelligent repair decision with facts. This is usually NOT an expensive
repair..... a set of this size may be worth the repair price as long as the
CRT still has good emissions.

 

[Charlie Bress]

Thanks for the tips.
I had tried some searches that were not productive, but I hadn't tried
Google groups.
I have a fair amount of experience with TV repair and I am well aware of the
shock hazards.
My biggest problem is that I haven't had much need to do component level
repair since everything went solid state.
That dates me, but the basics stay the same. It is the implementations that
have changed.

Charlie

 

[[email protected]]

Google Groups at sci.electronics.repair for "toshiba vertical" should
give you all the information. Many different models had the same
problems with capacitors.
Once you find the vertical output ic, the capacitors with the same
numbers C308,c301, etc.

Realize you won't be able to hit Radio Shack for suitable replacement
parts as they need to be high temperature and preferably low esr, high
precision capacitors. In that circuit if the small one 1uF or 2.2uf
change value with temperature, you will definitely see a change in
vertical size and linearity as the tv warms up.

As long as the capacitors have not damaged the vertical ic (some
deflection is still present to mostly full screen) then the capacitors
should be the full fix.

While you are in the tv there are some power supply capacitors that
often go bad soon after the vertical ones. Google for Toshiba power
supply capacitors. I think some of the locations were
c840,c822,c841,c863 etc. Exact locations can vary by model a bit.

 

[kip]

Yea ! Right.