[comp.sys.atari.st] SM124 monitor down, help!

litt@bnlux0.bnl.gov (Laurence Littenberg) (12/23/88)

	I have an SM124 (monochrome) monitor down with the capacitor
problem mentioned a couple of times recently on the net.  The repair
shop claims they can't get a proper replacement for the cap.  The
specs are 2.2uf @ 25volts which are not hard to come by.  But the
replacements work for a while (typically a couple of hours) then blow
out.  One possible hint at what's going on is that the original caps
are physically very large (barrel mount ~ 1/2" by ~ 3/4") whereas
available replacements are much smaller, and apparantly less robust.
The monitors in question were apparently made for Atari by Gold Star
in Korea.  Any suggestions?

rich@lakesys.UUCP (Richard Dankert) (12/26/88)

[]

In article <709@bnlux0.bnl.gov> litt@bnlux0.bnl.gov (Laurence Littenberg) writes:
>
>
>	I have an SM124 (monochrome) monitor 

	etc...

>specs are 2.2uf @ 25volts which are not hard to come by.  

>	 Any suggestions?


	Sure;

	Just use a larger size (as in working voltage) capacitor. The value
	the same, just that it's working voltage is larger. Should hold up 
	better,providing that there isn't something else causing the cap
	tp fry up.

	Typically with caps, you can go `larger' with both the value and the 
	working voltage, but this is dependant apon whether or not the 
	cap is used for timing purposes or not. To be safe, just get a 
	2.2uf @ 75 ~ 100 wv.

	Should solve the problems.......

	rich.....

	UUCP: rich@lakesys.lakesys.COM     {always .... }

chasm@killer.DALLAS.TX.US (Charles Marslett) (12/26/88)

A very critical parameter in a power supply cap is the amout of current
it can carry (ripple/AC or whatever) when being used as a filter.  This is
not normally printed on the case of the cap.  Typically larger (physically)
caps will have a lower ESR (don't know what that stands for, but high ESR
is real bad for a power supply cap).  So just go for the same voltage,
lower ESR (or physically larger package, or labeled "for power supplies".

Charles Marslett
chasm@killer.dallas.tx.us