Re: The 2e power supply

["Michael J. Mahon" <mjmahon@aol.com>]

Alex Freed wrote:
> Hi gang,
>
> I have just bought a 2e platinum on e-bay to help with the VGA 
> compatible card design. The problem is that is is only partially alive:
> the power supply delivers 3.4 volts instead of 5 volts and some 7v 
> instead of 12. So it only works as long as there are no cards in any slots.
>
> I have opened the (Dyna Corp) power supply and there is no trim-pot to 
> adjust. Wonder if anyone has schematics for it.
>
> Don't worry: after 25 years of electric engineering I know how not to 
> get electrocuted :))
>
> BTW the unit is not that old: made in 93. My ancient Apple ][ (no plus) 
> still works just fine.

The problem is almost certainly reduced capacitance in the line-side
filter.  If you look near the line input and diode bridge, there will
be 1-4 electrolytics with voltage ratings in the 150v-350v range.

If you replace them with capacitors that are at least as high in
capacitance and voltage rating, you should have a stable supply.

-michael

Parallel computing for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

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