Mylar Capacitors

[IIciNov90]

I am about to replace my old leaky caps on my IIci but before I go ahead and order them from Trag I wanted to see if anyone knew whether or not mylar capacitors might be an option for the big ones, the 470 microfarad and at least one other good sized one on the IIci motherboard. Mylar caps are those big yellow ones that resemble squashed cylinders. I have had success with them in the past in homemade crossover networks for speakers and I went to them for their durability after burning out or just outright melting electrolytics.

As far as I know there are no fluids in these guys. I think they are larger volume-wise for their capacitance so perhaps clearances may be the biggest hurdle.

Could anyone please weigh in?

thanks,

Brian

 

[IIciNov90]

Well I think I just found the answer, it is definitely due to size.

These things are absolute barrels for the capacitance that we need.

http://www.parts-express.com/wizards/searchResults.cfm?searchFilter=&srchExt=CAT&perPage=27&sortBy=3&layout=GRID&page=6&srchPrice=&srchCat=163&srchMfg=&srchPromo=&srchAttr=

I found some good selections for the 470uf though in electrolytic.

http://www.parts-express.com/wizards/searchResults.cfm?FTR=470uf&search_type=main&WebPage_ID=3&searchFilter=470uf&x=0&y=0

The axial type will be what I need. Are there any durability advantages to be gained by going with the higher voltage rated ones?

thanks,

Brian

 

[H3NRY]

A 470 uF mylar would be huge! Going up a step in voltage won't hurt, and may offer a bit better reliability, but the temperature rating is a better measure of how long they last. If you can find 105° rated, that's about the top for electrolytics. Higher voltage also means bigger size, which in turn means higher series resistance and inductance, so don't go overboard on voltage.