Are this caps something special?

[AndreStarTrek]

I been repairing special mainboard for a exposure machine but after replacing a chip and some cleaning it seems not to boot correctly so seen the machine is about 25 years, I have replaced all the caps with cheap chinees caps because that was something i have in stock. But after that there was no life at al. Been probing with a oscilloscope but noting.

So I been thinking, sure the cheap chinees caps are not the best but noting at all seems a bit strange. Are this something special?

[stj]

those are just regular - low-spec electrolytics.
i replace them all the time in sega gamegear consoles.

i would have replaced them with SMD tantalums

[AndreStarTrek]

Originally Posted by stj

those are just regular - low-spec electrolytics.
i replace them all the time in sega gamegear consoles.

i would have replaced them with SMD tantalums

Thanks, I take it using tantalum caps that capacity is not a big deal, if I at least meet the minimum requirements?

[stj]

tantalums are better and probably smaller

[AndreStarTrek]

Originally Posted by stj

tantalums are better and probably smaller

I understand that, but that was not what I was asking I like to know if it could be a problem if i use tantalums, would it be a problem if the capacity are bigger that the normal caps that are on the board right now?

I dont think it would, but want to be sure.

[stj]

there is no problem as long as the voltage rating is atleast 1.5x what it is connected to and you dont put them in backwards!

company's like apple and sun etc used to cover the boards in tantalum caps - the only reason they stopped is cost.

[budm]

Tantalum cap:
https://www.arrow.com/en/research-an...lum-capacitors

[Hitto]

Just use 50V parts and you should be okay. Kemet produces 50V parts for both 10 and 33uF tantalums, search for T52X serie.

Use a Panasonic [email protected] SMD electrolytic, it should fit. EEE-HC serie.

[AndreStarTrek]

Thanks for all you reply's.

[AndreStarTrek]

After 1 1/2 year this caps still haunts me.

After replacing the caps with the tantalums caps did not fix the problem it even create a problem, i found that out just recently.

After a year trying to fix this board we finally got a other board that worked. But this board has a lot of leaking/defective caps. So I replace 1/3 with tantalums and after that it wont boot, so i replace them again with caps that are not dead from a other donor board and the system boot again, but with a catch. We have to boot twice and I think this is because of the high resistance in the cap.

So i bought a ESR meter and got to work and the 33uf 16v caps has a ESR of 4.2 ohm with a 100KHz meter, and what i could find oud that is pretty high.

So I been searching for the right replacements and this are the one I found that could be it with my logic:
33uf 16v : https://nl.mouser.com/ProductDetail/...ZkYnMMng%3D%3D
10uf 16v : https://nl.mouser.com/ProductDetail/...52BHR3OQ%3D%3D
1uf 50v : https://nl.mouser.com/ProductDetail/...0g3nTfyA%3D%3D

So could it be that the tantalums are to fast? Are this caps the right one to replace with? Also a big chance i go with the radial version because this caps are even a bit to wide. I cant find a direct replacement for this cap.

In the end I am a bit lost, are this caps something special, could the tantalums be to fast and what should i replace it with? I hope someone could help me out.

[mockingbird]

Originally Posted by AndreStarTrek

So could it be that the tantalums are to fast? Are this caps the right one to replace with? Also a big chance i go with the radial version because this caps are even a bit to wide. I cant find a direct replacement for this cap.

I doubt it.. It could be you butchering the traces on the board with the iron... If those capacitors leakes, they may have weakened the traces or pads.

The caps you linked to are fine... I would probably use something like Panasonic FT, it has a higher endurance, and the last item you linked to is out of stock.

[stj]

check for electrolyte damage near the caps - those old boxed ones dump a surprising amount of liquid out!

[AndreStarTrek]

Originally Posted by mockingbird

I doubt it.. It could be you butchering the traces on the board with the iron... If those capacitors leakes, they may have weakened the traces or pads.

The caps you linked to are fine... I would probably use something like Panasonic FT, it has a higher endurance, and the last item you linked to is out of stock.

Originally Posted by stj

check for electrolyte damage near the caps - those old boxed ones dump a surprising amount of liquid out!

I am pretty sure the traces are fine. The solder points are a bit dirty but no leakes on the board. It helps that the caps hanging upside down on the board. I am also pretty sure there is no damage from soldering as I made sure i heat the pads as shortly as possible.

I wil take a look at the Panasonic FT caps but dont think the higher endurance is necessary, the setup only have to work for a few years.

Both thanks for the info

[sam_sam_sam]

Originally Posted by AndreStarTrek

I think this is because of the high resistance in the cap.

So i bought a ESR meter and got to work and the 33uf 16v caps has a ESR of 4.2 ohm with a 100KHz meter, and what i could find oud that is pretty high.

You would be correct that this value would be very high depending on what series you have it could range from 0.39 to around 1.something

The brand name that I use that are [email protected] volts read 0.39 new