Samsung SyncMaster 204B with bad caps, wondering if I can lower voltage

[Pentium4]

I have a 204B here with bad caps on the power supply...and guess what, they're CapXon! the whole PSU has:
3x 330uf 25V
2x 820uf 25V
1x 47uf 50V

the two 820's are bulged and the 330 next to the 820's.

I have exact replacements for the 47uf 50 cap and the 330's. What I was wondering is if I can replace the 820's with 1000uf 16V caps. If not, I have some 1000uf 25V caps that I'll have access to on Monday

[mariushm]

Re: Samsung SyncMaster 204B with bad caps, wondering if I can lower voltage

It's risky.

It varies from psu design to psu design. Some designs need 12v for the inverter section, others use a bit more. The problem is on some designs when there's no load, the voltage goes up a bit, so often the psu outputs 13-14v or more when the monitor is in stand-by or something like that.

I have for example an LG monitor on my desk now, one service manual says 18v for the inverter section and recommended 470uF 25v caps, another datasheet says 22v and recommends 470uF 35v capacitors.

I'm actually looking at the power supply and there's 28v (!) going through the board and the capacitors are 2 x 270uF 35v (Su'scon, they're ok on this psu)

Measure the voltages if you can, see where it idles at... then think if it's worth risking it.

[jetadm123]

Re: Samsung SyncMaster 204B with bad caps, wondering if I can lower voltage

They appear to be filter caps and I would wait until Monday to use the 1000uf/25V.

As mariushm pointed out, the 12V side of the power supply is unregulated and the output voltage can vary widely once the load is reduced. If you use the 16V caps, they will work, but not for long.

[Pentium4]

Re: Samsung SyncMaster 204B with bad caps, wondering if I can lower voltage

Thanks for the informative replies. Yeah I think I'll just wait till Monday. I'll update this thread with pics once it's finished