Date   : Wed, 17 Jun 2015 05:27:45 +0100
From   : profpep@... (Mike Pepper)
Subject: SJ Research MDFS Wiring Diagram

> On 14/06/2015 17:39, J.G.Harston wrote:
>> Michael Howard wrote:
>>>   I have 2 x MDFS which I'm trying to resurrect.
>> ...
>>>   I'm looking for a wiring diagram/schematics so I can find out what
>>> should be at C3 on the main PCB. One of the MDFS has nothing there and
>> The Community have been looking for technical info on the MDFSs for
>> year.
>> There was somebody up north who did MDFS repairs and SCSI/parity mods.
>> Somebody on here may remember who it was, there may be the possibilty he
>> still has some reference material.
> I wonder if he has ever been asked if he has any reference material?
>>   I bought my MDFS from him in 1998,
>> if I could find my receipt I could tell you who he was.
>>
> Well, no worries.
> If the next time somebody here opens up their MDFS I'd be grateful if
> they could let me know what is at C3 :)
>
> Cheers,
> Mike.

If it was a small 2-leaded 'blob', it was probably a tantalum capacitor 
across the power rails. One of tehir failure modes is to go short circuit, 
and since the power supply in the MDFS is quite 'beefy', they can then 
explode or burn away.

If it is such a thing, then it's non critical, and could be replaced with a 
small electrolytic.  A quick check with an Ohm meter will let you know if it 
was across the 5V rail.

Hope this helps

Mike