Fujitsu SL 3260W - high voltage ceramic cap replacement question

[Jooo]

Hi

I'm currently repairing an Fujitsu-Siemens 26" monitor. There is 12pF 3KV capacitor on the inverter section that has let out the magic smoke.
I have access to 10pF or 15pF 3KV capacitors, would it be OK to use a slightly different value capacitor there?

Thanks in advance.

[budm]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

The cap is ballast cap, its capacitve reactance is used to limit the current flow in the lamp once the lamp is on, so lower value will allow less current which is safer than using higher value cap that will allow more current flowing through the transformer and the lamp.
Do all 4 caps have the same value?

[Jooo]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

The cap is ballast cap, its capacitve reactance is used to limit the current flow in the lamp once the lamp is on, so lower value will allow less current which is safer than using higher value cap that will allow more current flowing through the transformer and the lamp.
Do all 4 caps have the same value?

Yes, all of them are same value. Would it be best to replace all four of them with 10pF caps?

[budm]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

I would check the winding resistance of that transformer and compare it to the other transformer to make sure it is not damaged first. Then put in just one cap to make sure the lamp still works, then replace the other.

[Jooo]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

Thanks, will do that. Actually the two inner capacitors are 300pF - while the two outer capacitors are 12pF

[budm]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

Are you sure two of the 4 blue caps are 300pF, at 3KV, 300pF will be bigger than that?

[re-atari]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

Hi
I'm currently repairing an Fujitsu-Siemens 26" monitor. There is 12pF 3KV capacitor on the inverter section that has let out the magic smoke.
I have access to 10pF or 15pF 3KV capacitors, would it be OK to use a slightly different value capacitor there?

I have the same monitor here on one of my PC's, the PSU is identical to yours. Last year it had exactly the same cap failed (c519). It was burned out even more than the one on your photo, looking like the head of a used matchstick. No markings readable anymore.

I chose a replacement by checking out how the caps are wired to the transformers. Turned out both inner caps c517 and c503 were of the same value, but differed with the outer one c504. I concluded the outer ones probably were of the same value as well. As c504 was 5p 3Kv, I replaced them both with new 5p 3Kv ones. As c517 and c503 looked ok, I just left them in place. Although c504 didn't show any sign of having run hot, like discoloring, I replaced it just to be sure. At a cost of only 10 cents each, no second thoughts. As much appreciated fellow forum user PlainBill used to say: 'Do it right, do it once; do it once, do it right'.

The monitor has worked perfectly ever since.

I suggest you replace not only c519 but c504 as well, on your photo it looks a bit discolored. You don't want to have to rip your monitor apart again in a few weeks time, just to replace yet another failed cap.

re-atari

[budm]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

You have to verify on how the caps are connected, in each set of the cap, one of them may be connected on parallel with the high voltage winding, if that is the case you must use the same value, the other is used as the ballast cap. That is why I ask if all four have the same value.

[Jooo]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

Are you sure two of the 4 blue caps are 300pF, at 3KV, 300pF will be bigger than that?

They were marked N3 3KV SEC, I thought that means 300pF, not 100% sure though.

I suggest you replace not only c519 but c504 as well, on your photo it looks a bit discolored. You don't want to have to rip your monitor apart again in a few weeks time, just to replace yet another failed cap.

re-atari

Yeah, ofcourse I replaced both. The second cap was indeed discolored.

You have to verify on how the caps are connected, in each set of the cap, one of them may be connected on parallel with the high voltage winding, if that is the case you must use the same value, the other is used as the ballast cap. That is why I ask if all four have the same value.

I understand.
I read on foreign forums that this is quite a common problem with this model.
There were other people that also had replaced the caps with slightly different value.
I was unable to get 12pF locally, so I replaced both of them with 10pF, and the monitor is working again.

[budm]

Re: Fujitsu SL 3260W - high voltage ceramic cap replacement question

N3 3KV, that is 3pF 3KV, very hard to get, I save lots of old boards for spare parts.