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Old 6th December 2006, 07:32 PM   #1
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Default Can IC's have intermittent faults?

...my chip amp is fine, but my beloved 21" trinitron monitor has an intermittent wig out with the vertical deflection control. Searches show that the obvious culprit would be the "IC007 chip on the "D board". It appears that this may be heat-related, since it doesn't start until 15-30 minutes after the monitor is turned on. If it were a purely analog circuit, I would suspect a bad electrolytic(and there are some feeding the chip), but alas, it isn't.

Sorry...have to go...it's about to start wiggin' out.

any ideas appreciated.
 
Old 6th December 2006, 08:47 PM   #2
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Fortunately it is rare but can happen. The most vulnerable area is the wire-bond.


Years ago I had a similar thing with the C-B junction of a BJT in an audio amplifier which would open a close with almost electronic-timer repeatability as the junction heated and cooled.

Freezer spray helps diagnosis.
 
Old 6th December 2006, 09:03 PM   #3
Nordic is offline Nordic  South Africa
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I was reading som application notes regarding opamps last night, and I believe its even possible to partialy damage the input stage to some... causeing things like, blue smoke of death, DC offset errors, thermal errors etc...
 
Old 6th December 2006, 09:58 PM   #4
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Default Re: Can IC's have intermittent faults?

Quote:
Originally posted by pedroskova
...my chip amp is fine, but my beloved 21" trinitron monitor has an intermittent wig out with the vertical deflection control. Searches show that the obvious culprit would be the "IC007 chip on the "D board". It appears that this may be heat-related, since it doesn't start until 15-30 minutes after the monitor is turned on. If it were a purely analog circuit, I would suspect a bad electrolytic(and there are some feeding the chip), but alas, it isn't.

Sorry...have to go...it's about to start wiggin' out.

any ideas appreciated.
This sort of problem is often evidence of a bad solder joint, something far more common than an intermittent failure in an IC. Take a soldering iron to the IC pins and see if the problem goes away.

I_F
 
Old 6th December 2006, 11:17 PM   #5
drj759 is offline drj759  United States
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I agree with "I_Forgot". The symptoms are typical of a bad solder joint. Furthermore, Sony TV's have a reputation for bad solder joints (search the web and see the Repair FAQ at www.repairfaq.org).

Quite a few years ago, our 15 yr old 19 inch Sony developed tuner troubles due to a know problem of bad solder joints. I had to install a rebuilt tuner module. Our 7 yr old 32 inch Sony lost half of it's picture a few months ago. A search of the web of the symptoms indicated a known problem with bad solder joints near the vertical deflection IC. I re-heated the joints near the IC and that brought the TV back to working order.
 
Old 6th December 2006, 11:19 PM   #6
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Due to the risks of working on CRTs by the inexperienced, we do not allow such discussions on diyAudio, so I have closed this thread.
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