Re: PSU Schematics for Mac II Power Supplies

On Mar 13, 2024, at 12:39, Stan Johnson <[email protected]> wrote:
> 
> Hello Hauke,
> 
>> On 3/13/24 4:06 AM, Hauke Fath wrote:
>>> On Tue, 12 Mar 2024 19:23:51 -0600, Stan Johnson wrote:
>>> Does anyone know where schematics for the following PSUs can be obtained?
>> 
>> The 68K MLA forums <https://68kmla.org/bb/index.php> are a good
>> starting point.
> 
> The 68K MLA forums do not appear to be a good starting point. I looked
> there, but I was not able to find any of these PSU schematics:
> 
> ASTEC AA15830
> ASTEC AA16870
> ASTEC AA15831
> DELTA SMP-120EB

In my experience, these power supply schematics are essentially impossible to find unless you find someone who has reverse engineered one (I saw one such claim a long time ago and never bought the schematic from them). My goal had been to fix up a Q700 power supply with an infamous startup issue, but I wound up finding a replacement supply instead.

If you’re looking to recap them, I would honestly just suggest opening them up, finding what values need replacing, and buying new high quality ones. Almost anything from a reputable vendor is likely to be better in terms of ESR and durability, just make sure you're getting the correct temperature grades.

- Dave