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Re: opening the 2c brick psu
In <1176613311.401890.12900@o5g2000hsb.googlegroups.com> phil wrote:
>
>>
>> You don't mention whether the 12v power supply you used was regulated,
>> or what the actual voltage was when the //c was switched on, but if
>> it can supply 12v under load, it should work.
> OK, I found the problem..
> When I crimped the strain relief in the back of the power in DIN plug,
> It shorted the plus with the housing ground, so plugging in the lead
> in shorted my 12V psu. Oops. The fuse f1 (yellow, behind power switch
> inside 2c unit) did pop also, so if anyone knows what to replace it
> with, that would be good. I'm using a 2A one for now...
According to the Apple IIc Technical Reference Manual it's a 10 amp fuse.
That seems ridiculously high to me, but it doesn't look like a
misprinting and 1.0A would be too low. The manual says the internal
switching power supply can run from 9V to 20V and consumes a maximum of
25W, so at 12V it could draw peak currents of around 2A.
Check that the diode CR1 isn't shorted. It's a reverse polarity
protection diode connected from the positive to negative supply input
lines immediately after the fuse.
> My 15V brick outputs no power at all, so if anyone can please give me
> a hint on where the plastic casing is welded together... Thanks.
I had to open a IIc power brick up a few years ago. From memory the two
plastic halves are glued together around the entire seam. I used a vice
to repeatedly squeeze the brick around the seam until it broke and I
could get a screwdriver in to lever the two halves apart. The only other
option is to use a fine-bladed saw to cut it open. Designers (or
accountants) who save a few cents on screws by glueing cases together:
first against the wall when the revolution comes!
--
* Roger Johnstone, Invercargill, New Zealand -> http://roger.geek.nz
* PS/2 Mouse Adapter for vintage Apple II or Mac
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