Re: AppleColor Composite Caps

[srkh28@gmail.com]

Ive taken the chance to replace the caps in the my IIe's power supply.
There has always been the odd complaint (we'll actually a plethora of
complaints) about how the II's supply never having a fan. We'll after
28 years of service, the caps finally gave out - and because the
enclosure has no vents (or a stupid fan for that matter) the supply
inside looks as new as the day it was made - as clean as - a total
pleasure to work on. I dont know if anyone has worked on PC power
supplies 9or any supply wit a fan for that matter), but after a mere
few year in use, the fan sucks in is so much dust, grime and smokers
gooey tar, that you would rather work on a dead rat than a grubby
power supply.

Ill take some piccies of the caps being replaced if anyone is
interested in doing the same to theirs.

steve


On May 26, 6:35 am, MdntTrain <j...@cimmeri.com> wrote:
>   Short story for those, if any, who are curious about the A2M6020
> composite monitor.
>
>   My video input jack had become loose, so I removed the female
> portion while leaving the vertical ground bracket in place.  I then
> installed a regular 1/4" phono jack in the old hole.  Works much
> better since you can screw it down.
>
>    Also decided to check all the electrolytics while I was in there.
> My monitor was made in Nov 1989.   I tested all in circuit for ESR and
> capacitance.  Wasn't able to measure capac. on all.
>
>     As I kinda expected, all the physically large caps had good ESR
> and capacity (of those where that showed); and the two smallest ones,
> while they generally test higher anyway, these tested abnormally
> high.      The single 1uf/250V/85c AEC on the neckboard had very high
> ESR (not surprising given its location right next to a regulator with
> a large heat sink), and also the one next to the HV cage (1uf/160V)
> nestled tightly between a bunch of components.
>
>     I replaced the neckboard with a 1uf/250V/105c AEC, and the other
> one with a 1uf/100V monolithic ceramic.  I checked the running voltage
> across it and it was only 35V... plus it didn't explode after many
> hours of use.
>
>    The moral of this story is that, if you didn't know it already,
> caps are starting to go.. beginning with the smallest ones that dry
> out the easiest.
>
>    If I'm left with any question here, it's just over how effective is
> ESR alone in checking caps?  It's certainly the easiest one to perform
> if you have a meter.    But do we also need to be checking for
> capacitance and leakage to get a true overall picture of the cap
> health?   Or does high ESR tend to go hand-in-hand with leakage or
> capac. loss?
>
>   jS