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Hitachi shut down

I posted this same problem a few times in the last 3-4 weeks. The set
will not power up. Model #50EX10B. I have checked, replaced, and
checked some more, various components. I have traced a problem to the
system IC0001 and eeprom IC0002. I should have 5 volts at pin #44 of
IC0001 (on/off) circuit, but I have 0 volts. I should have 0 volts at
pin 3,4 of eeprom, but I have 5 volts. I scoped the data lines on the
eeprom, but I don't see any type of data, only steady 5 volts. I am
aware that corrupted eeproms can cause many different problems for a
TV, and am suspecting this as the culprit to all my problems, since
some of the problems are intermittent. The B+ wasn't regulated (198
volts), kept blowing fuse, blew Hot twice, etc. Now the set won't do
any of this. Only relay clicks on/off with power button. Would a faulty
eeprom cause all these problems, including missing the 5 volts on pin
44 of system IC? Anything further I can check/test here before
replacing another component? Thanks a bunch group for all you responses
and help to this point.
 
J

Jeff Rigby

Jan 1, 1970
0
I posted this same problem a few times in the last 3-4 weeks. The set
will not power up. Model #50EX10B. I have checked, replaced, and
checked some more, various components. I have traced a problem to the
system IC0001 and eeprom IC0002. I should have 5 volts at pin #44 of
IC0001 (on/off) circuit, but I have 0 volts. I should have 0 volts at
pin 3,4 of eeprom, but I have 5 volts. I scoped the data lines on the
eeprom, but I don't see any type of data, only steady 5 volts. I am
aware that corrupted eeproms can cause many different problems for a
TV, and am suspecting this as the culprit to all my problems, since
some of the problems are intermittent. The B+ wasn't regulated (198
volts), kept blowing fuse, blew Hot twice, etc. Now the set won't do
any of this. Only relay clicks on/off with power button. Would a faulty
eeprom cause all these problems, including missing the 5 volts on pin
44 of system IC? Anything further I can check/test here before
replacing another component? Thanks a bunch group for all you responses
and help to this point.


If you have a switching power supply problem and have too much B+ to the
Horiz output and if you defeat shutdown you will break the Green CRT. First
problem. Now you probably have other problems since the fuse blew to the
horiz out. Too much voltage to the other circuits can cause problems there
too.
 
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