LG 32LX2R Faulty power supply.

A LG 32" LCD TV that would not power on, the fault occurred following a mains power outage.

The PSU board looked fine, no bulging or stained capacitors. Aquick google went straight to the point, somebody with identical experiences who recommended changing the output stage capacitors (circled) anyway.

http://forums.moneysavingexpert.com/showthread.php?p=27092505

post number #31

The capacitors were sourced, 14 in all. The board was of reasonable quality, no problems removing the old ones.

Here is a close up, all the old capacitors looking ok

So in went the caps. I measured all the old capacitors and they were all in spec for capacity on a basic Fluke multimeter....

However the TV now worked. I would be interested to know the failure mechanism of the capacitors but a good result and Google delivered as the capacitors really dint look suspicious.

Update:

Here is the capacitor list:

2200uf 10v x 1
1000uf 35v x 4
1000uf 25v x 2
1000uf 10v x 3
680uf   25v  x 2
100uf   50v  x 2

Update:

The likely failure for the capacitors is poor ESR, (equivelant series resistance) at given frequencies. I have access to a proper LCR bridge. A quick measure shows ESR varies with physical size on new capacitors, I will need to look into specs for given values and see if there is a large deviation from spec.

Update:

Ok, I had kept the capacitors and measured them all. Here is a table of typical ESR values. This is from a manual of an ESR meter made by Peak electronics. I hope they dont mind me using it, here is a link to there meter http://www.peakelec.co.uk/acatalog/jz_esr60.html

There are three 10v 1000uf capacitors in the TV PSU, two measured just under 0.2ohms but one measured 2.1 ohms, so it looks like this was the likely culprit.

The esr meter above can be used in circuit, I hope to try one out soon !