Hitachi Ultravision Model 50UX26B Intermittent Power Shut Down

We have a Hitachi Ultravision Model 50UX26B projection TV that was
made in July 1996. Lately it has been shutting itself off at random
times. Hitting the power button on the remote usually turns it back
on again (you actually need to hit the power button twice; the first
time you hear the TV click and the second time it comes on).

I don't think it is heat related because it's done it shortly after
turning it on sometimes. Other times it will run for a long time
without problem. The frequency of the intermittent shut downs has
progressively increased from infrequent to several times an hour. Now,
we can't power the TV on except occasionally and then it doesn't stay
on for long. When we hit the power button the TV would click and the
power light would flash on briefly but wouldn't stay on.

Does anyone have any ideas what is wrong with our TV and how it can be
fixed? We'ev found several other posts to Usenet where people have had
the same problem, however, we haven't seen a definitive fix, and no
one has followed up to say whether the advised fixes actually worked.
Of course, we are hesitant to call a repair service and spend a pile
of money only to have the problem continue...

Thanks for you help.

Angela D'Andrea
Austin, Texas

 

It's probably just a cracked solder joint in the power supply or horizontal
deflection system, if the picture is good I suggest calling a pro unless you
have good soldering skills and are able to identify subsystems by looking at
the boards to know where to look for the bad joints. The repair should be
fairly straightforward for an experienced tech though.

 

AP63 Chassis

Inspect all electrolytic capacitors for leakage and ESR, resolder the common
areas that are problems. Check for defective components and bad solder
connections:

I601
D936
Q003
I901
I907
R913
I401
T701
T901
L708

and a few dozen more parts. Troubleshooting would narrow it down to the
problem area more effectively.

Or call a tech that has some experience with these sets.

Leonard Caillouet

 

Angela,

I have the same model manufactured at approximately the same time frame. We
have not experienced the problem you describe, but I did have the main power
on/off relay go bad so it had to be replaced. I only mention this since it
was a pretty easy fix and if you can't find any cold solder joints on the
main
power board you may want to check the resistance of the relay contacts
themselves (mine would stick closed after the set was turned off, but I
could
imagine that they could just as easily become resistive and have the
potential to
fail in the manner you describe as well).

After dismissing cold solder and checking the other components Leonard
cited, I'd look at the relay. Hope you can get this fixed. We still love
our set. If you need a schematic, let me know as I think I have the service
manual somewhere.

Bob

 

I too have the same model television. It seems this is the most commo
problem for these units. On mine however, you can hear the tv clic
when you press the power button. I have removed the back and the fus
is still good. In fact the red indicator light (on the circuit boar
inside tv) comes on when you turn the tv on. Neither the outsid
indicator light or the screen however come on. Its as if the tv i
turning partially on, but not all the way. Any advice would be helpful
I just dont see the reason to take it to a repair shop. I'd rather se
if I can get it fixed myself. And if anyone has the service manual fo
it... I would appreciate that too. Thanks

Matt Walker (),
Lubbock TX

 

This is a common scenario.

Careful! The main filter caps bite hard on these!

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Text pasted from WinSTIPS 2.0
http://www.ServiceSoftware.com
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HITACHI 50UX26B

Shuts Down Randomly. May Take 2 Hours Or 2 Minutes.

Jeff Stielau : 2/19/03 : Shoreline Electronics

After Pulling The Chassis & Resolder All Heatsinked Parts & Connectors (
None Looked Suspicious To Begin With) Problem Still Existed.
Replacing The Strm6511 (Ici1901) Fixed The Set. Change The 2 Small
Electrolytics Next To It For Good Measure.

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Jeff Stielau
Shoreline Electronics Repair
344 East Main Street
Clinton,CT 06413
860-399-1861
860-664-3535 (fax)

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