Sharp 3LS36 - partial vertical collapse from bad C509

[japlytic]

Today, I got a Sharp 3LS36 TV which had the problem of a partial vertical collapse where only a third of the screen can be filled with a picture.
So I tried replacing capacitors C501 (with a tantalum unit), C503, C506, and C509 in the Vertical section, and measured the originals with my handy capacitor tester.
Upon measuring the original 1000uF 10V unit (Nichicon VX Series) which was used in position C509, I got an off the scale reading (even at the highest range of up to 20,000uF) on my capacitor tester, which showed that this capacitor was defective, even though the others I mentioned earlier are probably still good.
C509 was upgraded to a 16V unit as a good measure since the main power rail used by the vertical output stage is 10.7V.

As a good measure, C615 was replaced with a low-ESR unit, along with C705, and the following capacitor upgrades were also done:
C701: 1000uF 25V (originally 100uF)
C704: 1000uF 16V (originally 330uF)
C623 and C624: 10uF 160V

[ben7]

Re: Sharp 3LS36 - partial vertical collapse from bad C509

The bad nichicon wasn't bulged was it?

Yeah I have heard before the capacitance can increase sometimes when the capacitor fails.

Poor 'nichi ... that shows that all capacitors are the same, in this respect - they all can fail, even the good ones

[japlytic]

Re: Sharp 3LS36 - partial vertical collapse from bad C509

The bad nichicon wasn't bulged was it?

Yeah I have heard before the capacitance can increase sometimes when the capacitor fails.

Poor 'nichi ... that shows that all capacitors are the same, in this respect - they all can fail, even the good ones

This capacitor had no visible signs of being bad - you are certainly right about even the best electrolytics are not immune from failure.

[Wester547]

Re: Sharp 3LS36 - partial vertical collapse from bad C509

VX is an 85*C capacitor, that's probably why it failed in that application...

Poor 'nichi ... that shows that all capacitors are the same, in this respect - they all can fail, even the good ones

Some are worse than others (more aqueuous ones may expand more with exposure to heat but it also depends on the other additives used in the electrolyte and the quality of the inhibitors), but I suppose the quality does vary even in the Japanese supply chain... I would not fault Nichicon. I think the only vaguely similar capacitors that can really take excessive heat (besides non-aqueous lytics maybe, assuming that the heat is not of discolorating range) are functional or solid polymers.