Samsung LCD PS - Change 150μF/450V?

[Chumly]

Hey, new to posting but have been lurking for years. Now I have a subjective question for ya'll.

About 8 years back I picked up a bunch of plagued Samsung 204B LCD's from work. It's just as much trouble to dispose of them so I decided to repair them instead. They all seemed to have the same bad condensers on each and everyone of them (CapXon 680μF &330μF / 25V) which I replaced. I didn't have an ESR meter back then to test the big one so I just replaced the obvious bad ones With Ruby's and all worked for a very long time (donated them and no complaints).

Fast forward: I just brought home a bunch of dead 225BW's and 2 more 204B's from work. The PSU's seem to be the same build, just some minor changes, and the exact same bad caps to replace. Now that I have an Anatek Blue ESR meter I was able to test the larger CapXon 150μF/450V cap and all seem to be just fine. No bulging, darn near perfect ESR readings, past repairs seem to be fine; but they're still CapXon brand.

I've got 26 of these PS's lined up and was wondering if you'd personally change these big caps with a reputable brand just because they're CapXon and I have them all open, or just leave 'em be and hope for the best? There's one of these on each power supply, the store here doesn't list them as being stocked, and sourcing them locally is darn near impossible (I have Radio Shack which doesn't stock much these days, and Fry's which carry iffy brands...if you happen to find more than 3 at a time on the rack). Mouser Inc is another option I guess.

So would you bother replacing a cap that appears to be fine but has a bad reputation, Think I should ask TopCat if he can source some for me and just do it while they're open, or just roll the dice and spit these things out with one CapXon still in there? I can post pics if needed, but probably not needed. I Would like to start this repair process next week as they really do take up a lot of space and I have 7 days off from work. Going to keep 4 of them then donate the rest, so I hate to give something away that I'm not really sure of 100%.

(Sorry for being wordy...that's me :p)

[selldoor]

Re: Samsung LCD PS - Change 150μF/450V?

I am relatively new to this forum and I am sure others will respond. Capxon
smaller caps come into the replace on sight category, however the general rule is that there is no need to change the big cap (whatever make) unless it shows
signs of bulging or leaking or has exploded!!.
You have done one better by testing them with an esr meter so I would just leave them in.

[retiredcaps]

Re: Samsung LCD PS - Change 150μF/450V?

Now that I have an Anatek Blue ESR meter I was able to test the larger CapXon 150μF/450V cap and all seem to be just fine. No bulging, darn near perfect ESR readings, past repairs seem to be fine; but they're still CapXon brand.

Mouser or digikey have replacements and they range from $3 to $5 each with discounts for 10 or more.

The big filter cap doesn't undergo the same stress as the secondary caps. See

https://www.badcaps.net/forum/showthread.php?t=15692

[Chumly]

Re: Samsung LCD PS - Change 150μF/450V?

Perfect link, thanks! I did search but not well enough obviously.

I never went so far as figure out what exactly they do in the circuit. These big caps are in a section of the PS that appear to be in the line voltage side (60Hz/120VAC here), do seem to be filters, and did see prices in the ballpark you've noted. That last part is what got me as it will double the cost to repair them all and decided to ask if you'd even bother. Peace of mind is always helpful and I very much appreciate it!

I feel comfortable leaving them all in now. What I figure I'll do though is replace 2 of the 4 I'm keeping just to see what happens as an experiment. Keeping two 204B's and two 225BW's, so I will put a good condenser in one of each and watch them. Going in 2 different garages which isn't really harsh conditions, but not optimal for sure.

Just for reference, the 204's lasted 2 years of daily use and the 225's went 3 years. One was my personal purchase and my first LCD to replace the awesome Sony 22" CRT that went 4 years before the blinking blue light. It's very ironic that you pull something apart from 8 years ago and 4 years ago to not just see the same blown caps, but also the same power supply basically.

[retiredcaps]

Re: Samsung LCD PS - Change 150μF/450V?

Just for reference, the 204's lasted 2 years of daily use and the 225's went 3 years.

The ccfls are rated to last anywhere between 40,000 and 60,000 hours so you should still have some decent life in them.

[momaka]

Re: Samsung LCD PS - Change 150μF/450V?

Generally, the big high voltage caps on the primary don't need to be replaced. HOWEVER, if the power supply has active PFC (APFC) and the caps are known to be a problematic brand, then change them. I've seen 2 or 3 PSUs now on this forum with blown PFC diodes/transistors due to CapXon high voltage capacitors on the primary going open-circuit.