Author Topic: Toshiba 32HL67U - Lightning Damage?  (Read 652 times)

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Offline Sceptre

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Toshiba 32HL67U - Lightning Damage?
« on: December 04, 2016, 04:33:56 am »
I'm trying to diagnose a broken Toshiba 32HL67U power supply.  When I removed the V28A00030801 assembly from the TV, I noticed a couple burn marks on the chassis, corresponding to marks on the PCB (near R869 and R806) per the attached picture.  Are these characteristic of lightning damage, or could they just be arcing from a malfunctioning supply? I don't want to put any more time and effort into this if there may be more damage downstream (as can be the case with a lightning strike).

The first issue that I found with the PS was an open F802 (HOT_DC_MAIN to main DC-DC controller Q801).  The replacement fuse did not blow, but there were still no outputs.  I then determined that START_UP_SUB to QE01 was low and pulsating (when read with a DMM), though the voltage is steady on the other side of the dropping resistor (i.e. after the full-wave rectifier).  It's not clear to me whether QE01 is broken or if an output short is causing it to cycle into shutdown.  I checked cap ESR values (as seen in the picture, C816 and C827 were removed for testing) and diode/transistor junctions, but didn't find any problems.  One burn mark is on the DRIVCC signal to Q801 (Pin 9); the other is on the 5V1 coil pin of relay SR81, which supplies AC to the HOT_DC_MAIN full-wave bridge.  The pins are relatively long on the solder side, but there are plenty others which are just as long.

Thanks for any insight or guidance!
 

Offline amyk

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Re: Toshiba 32HL67U - Lightning Damage?
« Reply #1 on: December 04, 2016, 04:01:16 pm »
Lightning damage will be far worse than that.
 
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Offline Sceptre

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Re: Toshiba 32HL67U - Lightning Damage?
« Reply #2 on: January 21, 2017, 03:39:20 am »
A belated thanks for that response, amy.  Still looking for hints regarding how to isolate this failure.  Anyone?
 


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