S-100 power supply transformer

js at cimmeri.com js at cimmeri.com
Mon May 18 10:13:41 CDT 2009

>> In my IMSAI, I feed each board power from a dedicated, pluggable line 
>> running to it... ground is still done through the connector.
> David Griffith wrote: What did you do with the power feeds on the 
> backplane?  Got any pics?
The original backplane wiring is left intact... so unconverted cards 
will still work.

I do have a photo.   Email me direct at js at cimmeri.com.

> Alexandre Souza wrote:   The problem is compatibility. Imagine that 
> each S-100 board you would connect on your system has to be modified. 
> And every board that will be sold, lended or given away, will ALSO 
> have to be modified.
>    Why not just change the regulator for a newer one? They are so 
> cheap nowadays :o) 
I get around the compatibility issue by leaving the original backplane 
power in place.  Btw, this regulator failure problem is only showing up 
on the 5V line.   I've not had any issue with the 12V regulators.    So, 
I run a separate unregulated 8V wire from the primary PSU over to my 
regulator board.   This board has the new 5V regulated rail.   Wires 
from cards that have been converted plug in here.   I don't have a lot 
of cards, so conversion is not a big deal... but I find converting the 
card easier than replacing its regulator + associated caps.

You can just replace the regulator... but the job is not just the 
regulator... it's also all the supporting caps.    If the design 
overstressed the regulator to begin with, then you are back where you 
started with a high heat situation.


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