CBM 1541 drive faults

[Jules Richardson]

On 12/13/2015 09:22 AM, tony duell wrote:
>>
>> I've done the obvious, reseating socketed ICs, checking the +12V and +5
>> rails, and checking the on-board CPU reset line. Does anyone have any tips
>> for what's best to try next?
>
> Didn't at least some versions use 2114 RAM chips? If so, then check/change
> those first

Yes, I've certainly seen that on the schematics, and was considering them 
as a likely failure too - after opening cases though, my drives all seem to 
have a single larger SRAM (even the Rev A board, so that's presumably "Rev 
A of the type that doesn't use 2114's" :-)

While 2114's could be somewhat unreliable, I think the larger (6116 etc.) 
SRAMs are generally OK; while a fault there is a possibility, I'm thinking 
that the failure is likely elsewhere.

(Aside: Why on Earth do people scan schematics as bi-level images? I've not 
found a good 1541 schematic yet - the ones out there are all high 
resolution, but the depth reduction renders component information unreadable)

Jules