125 degree C electrolytics by Su'scon

[flippineck]

I'm attempting to repair a 22" HP LCD monitor.which powers up in a very delayed fashin, by replacing the electrolytic capacitors on the power board.

I've obtained most of the capacitors I need very easily, but three are proving very hard to obtain the identical spec to that currently fitted:

Manufacturer: Su'scon / Kuan Kun Electronic Enterprise Co., Ltd
SH Series / High temperature,RADIAL Electrolytic Capacitor for 125℃
http://www.su-scon.com/Templates/att/SH.pdf?lng=en

10 microfarad, 25 volt, 125 degree C
47 microfarad, 25 volt, 125 degree C
470 microfarad, 16 volt, 125 degree C

The 125 degree C temperature rating seems to be the problem, all of the suppliers I've tried haven't got them.

I guess I could just ignore those caps (visually they look ok) and hope for the best, of if that fails, try replacing them with 105 degree caps.. but I wondered, if anybody knew a supplier (ideally in UK) that did offer 125 degree caps in small quantities?

Tried CPC and RS but no luck (found the selection options a bit confusing though so maybe I wasn't working it right), Maplin's shutting down and not really sure where else to try

Looks like Su'scon electrolytics had something of a bad rep for a time.. http://www.shaddack.twibright.com/projects/badcaps/

 

[kellys_eye]

I wouldn't bother - 105^oC should be more than sufficient.

 

[flippineck]

Red arrowed ones are the 125 deg C capacitors. All the rest are 105.

 

[dave9]

Yes use 105C, and you probably only needed to replace those that are bulged on top (and those parallel in the circuit to the buldged caps if that is the case with some), in other words the entire row of medium & larger caps to the left of the heatsink as pictured, with the other important parameter being that they're very low ESR. If the ones you have aren't very low ESR I would not bother using them.

 

[kellys_eye]

Lots of nasty bulging capacitors on that board!

There's no rhyme or reason behind them using 125C versions as the temperature will be pretty much the same for all of them in the area so if they've used 105C versions elsewhere you may as well use them everywhere.

 

[flippineck]

Thanks folks, soldering in what I've got.. will then stand well back before flicking switch. You have me concerned now regarding low ESR

What I've ordered are all Panasonic FR series

 

[dave9]

^ ESR higher than optimal may work for a while, hopefully not allowing a damaging (or instability causing) level of ripple, but will tend to fail again much sooner and when a PSU circuit fails there's a chance it damages something.

Always use very low ESR caps on the output of a switching PSU circuit.

 

[flippineck]

Just found & checked the datasheet for the Panasonic FR series caps I used - it does say they are low ESR. Phew.

Noticed it says 'endurance at 105 deg C - 5000/10000 hrs'. Given the fact I tended to leave this monitor switched on 24/7, I guess I'm lucky it's lasted as long as it has! Given that a year works out at 8736 hours

Monitor (a HP w2207) now working fine after replacing all caps on the power / inverter board except those 125 degree ones. Thanks for the help