Maker Pro
Maker Pro

Hitachi turns itself off

Here we go again. Hitachi model #50EX10B. Replaced the green CRT. Works
fine, just have serious mis-convergence that I'm working on. Anyway,
now the darn thing tuns itself off after playing for about 20 minutes.
Hit power button and hear relay click. Wait about 30 seconds, hit power
button again and set comes back on. About 3-5 minutes later, goes
though the same sequence. I'm guessing it's heat related? Just not sure
where to start looking. Any ideas? Thanks group.
 
Here we go again. Hitachi model #50EX10B. Replaced the green CRT. Works

fine, just have serious mis-convergence that I'm working on. Anyway,
now the darn thing tuns itself off after playing for about 20 minutes.
Hit power button and hear relay click. Wait about 30 seconds, hit power

button again and set comes back on. About 3-5 minutes later, goes
though the same sequence. I'm guessing it's heat related? Just not sure

where to start looking. Any ideas? Thanks group.

No idea's? Anyone please?
 
T

Tom MacIntyre

Jan 1, 1970
0
Here we go again. Hitachi model #50EX10B. Replaced the green CRT. Works
fine, just have serious mis-convergence that I'm working on. Anyway,
now the darn thing tuns itself off after playing for about 20 minutes.
Hit power button and hear relay click. Wait about 30 seconds, hit power
button again and set comes back on. About 3-5 minutes later, goes
though the same sequence. I'm guessing it's heat related? Just not sure
where to start looking. Any ideas? Thanks group.

Guess answer...coolant spill?

Tom
 
K

kip

Jan 1, 1970
0
Maybe if you repair the serious mis convergence
you would also correct the shutdown..
kip
 
T

Thirsty

Jan 1, 1970
0
I don't know this particular set but I repaired a Zenith in years past
that had a problem of turning itself on at all hours of the night.
Problem was silver migration on the the pcb (in the TV) that receives
the transmission from the remote control. Solved problem by cleaning
between the traces with a pencil eraser.

Maybe your set thinks it is receiving an "off" transmission from the
remote.
 
I wish. I replaced the green CRT with a new one. After this, the set
powered up OK, but convergence was bad, especially the blue. Adjusted
the static, then dynamic (fun) convergence, and picture is close to
accepable, but not quite. Anyhow, like I said, once powered on
initially, it stays on longer prior to shutdown than after shutdown and
powered back up. One more clue, if I don't leave the set shut down for
at least 20-30 seconds, and power it up again, the picture seems to
display interference like bad reception, but will clear itself up after
a minute or so, then will shut back down as said after a few minutes.
Prior to changing the CRT, when hitting the power button, the set would
try to power up (red led come on), then shut down. Only way to power
back up was to unplug it, plug back in, and turn on. The set would then
stay powered up. Of course it got to where it wouldn't power back up -
fracture in green CRT neck, causing shut down, and blowing fuses,
Hots's, etc. There seems to be a definite time period I have to wait
before the set will power back up - 10-20 seconds. Does this sound like
a possible capacitor problem, leaky diode? I tried freeze spraying
everything, but nothing found yet. Thanks for the replies to all. Still
hoping for one hot tip.
 
K

kip

Jan 1, 1970
0
What is the number of the regulator in that set..

kip

..
 
I wish. I replaced the green CRT with a new one. After this, the set
powered up OK, but convergence was bad, especially the blue. Adjusted
the static, then dynamic (fun) convergence, and picture is close to
accepable, but not quite. Anyhow, like I said, once powered on
initially, it stays on longer prior to shutdown than after shutdown and
powered back up. One more clue, if I don't leave the set shut down for
at least 20-30 seconds, and power it up again, the picture seems to
display interference like bad reception, but will clear itself up after
a minute or so, then will shut back down as said after a few minutes.
Prior to changing the CRT, when hitting the power button, the set would
try to power up (red led come on), then shut down. Only way to power
back up was to unplug it, plug back in, and turn on. The set would then
stay powered up. Of course it got to where it wouldn't power back up -
fracture in green CRT neck, causing shut down, and blowing fuses,
Hots's, etc. There seems to be a definite time period I have to wait
before the set will power back up - 10-20 seconds. Does this sound like
a possible capacitor problem, leaky diode? I tried freeze spraying
everything, but nothing found yet. Thanks for the replies to all. Still
hoping for one hot tip.

I would look into the deflection and convergence circuits, seriously. Do
you think that green CRT cracked all by itself? Do you think there is
no logical reason for protection circuits to be kicking in after some
part of the convergence heats up beyond safe limits?
 
Yes I do, but I am a beginner in repair. I have been told by a friend
(TV repair man) that this is not uncommon in older TV's for a hair line
fracture to develop. Maybe from sub-standard production, etc? Anyway, I
am still fiddling with the convergence adjustments, likely because I am
avoiding the shut down issue. If the set was shutting down by
protection circuits, would it power back up after a short time period
without unplugging the set? Thanks for the reply.
 
T

Thirsty

Jan 1, 1970
0
Are you convinced the degauss is turning off properly (you mentioned
a click)? You might try disabling the degauss circuit, to see if
there is any change.
 
Top