[vcf-midatlantic] SASI Hard Drive Controllers

[Dan Roganti]

On Sat, Dec 17, 2016 at 6:04 PM, Jonathan Gevaryahu via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

> On 12/17/2016 11:03 AM, Dan Roganti via vcf-midatlantic wrote:
>
>> On Sat, Dec 17, 2016 at 10:06 AM, william degnan via vcf-midatlantic <
>> vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:
>>
>> Related to my post yesterday, I have a SASI XEBEC 104526 rev 4 that works
>>> ok when there is a fan blowing on it but overheats after a while.  It
>>> controls a SASI external hard drive used by a Visual 1050 computer.  OK,
>>> I
>>> will look through the electronics and replace failing components and sure
>>> it up.  Seems like the typical course of action for an XEBEC and other
>>> (SASI) external controllers.  I am also thinking about the CBM 9090 and
>>> related 5-10Mb drives. 35 years in, they all seem to be failed or
>>> failing.
>>> Similar XEBEC controllers for things like IBM PC's seem to have fared
>>> better.  Why?  Or just a coincidence?  Is there a common component that
>>> fails more often in SASI controllers but not IDE and others of the era?
>>>
>>> I know the history of SASI/SCSI and I have some XEBEC docs.    I can
>>> research further on my own, but maybe someone who actually supported
>>> these
>>> back when they were new has some casual knowledge to pass along.  How
>>> reliable were these when they were new/current?
>>>
>>> Bill
>>>
>>>
>> ​I don't have any repair history of that board, I think that's a long shot
>> Unless you find someone who worked at XEBEC, they would have a more
>> comprehensive view of failures.
>> And most if not all of those components are well beyond their mtbf rating
>> already.
>> So that basically means, anything can go wrong.
>> But the basic repair steps for something like this include several options
>> One of which is using a ol' tried and true method of finding the hot
>> component, your finger :)
>> That's if the slot has room for you to get in there.
>> There's other options such as using a temperature probe[thermocouple]
>> adapter for your DMM.
>> So you can measure the heat from each component.
>> Also, for these tricky problems it helps to have a thermal imager -
>> they're
>> getting cheaper every year.
>> Then you can pinpoint the source of the heat, but first turn off the Fan
>> :)
>> Dan
>> .
>>
>> Can't you use a FLIR or similar thermal camera to figure out which IC or
> capacitor has a partial/internal short, and replace just that one?
> Keep in mind that some ICs normally get hotter than others, though.
>
>
​that was in my 3rd option
​