Samsung 47" Blown Convergence IC

[Chris F.]

I made the mistake of buying this Samsung HCN4727 to fix for resale, it
had a blown convergence IC (STK392-040, I think) so I thought it was an easy
fix. After replacing the IC, the set did work fine for the next week or so.
After a total of about 20 hours of operation, the picture started getting
jitters, and finally the same convergence IC failed again. I confirmed it by
subbing with a known good (but lesser wattage type -010) IC. At this point
I'm wondering if the replacement part was defective, or what if any
underlying cause there could be. Nothing seems out of the ordinary, both
IC's run at the same temperature and there are no other obvious problems
(bad caps, solder, etc.).
Just thought I'd get some advice before I put any more money into this
stupid thing.

 

[Meat Plow]

On Sun, 05 Dec 2010 16:41:56 -0800, Chris F. wrote:

I made the mistake of buying this Samsung HCN4727 to fix for resale, it
had a blown convergence IC (STK392-040, I think) so I thought it was an
easy fix. After replacing the IC, the set did work fine for the next
week or so. After a total of about 20 hours of operation, the picture
started getting jitters, and finally the same convergence IC failed
again. I confirmed it by subbing with a known good (but lesser wattage
type -010) IC. At this point I'm wondering if the replacement part was
defective, or what if any underlying cause there could be. Nothing seems
out of the ordinary, both IC's run at the same temperature and there are
no other obvious problems (bad caps, solder, etc.).
Just thought I'd get some advice before I put any more money into this
stupid thing.

Check the low value resistors in and around the IC circuits. A lot of
times when the IC's blow it will take a few of those out. They are like
10 ohm @ 1/8 watt. Make damn sure you clean the heat sink off and use new
thermal compound applied appropriately. And make sure you torque the
chips down to the sink properly. I'm not sure of Samsung 47's being a
convergence IC 'eater' but i might have read something to the effect.



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