Need help or service manual for RS COCO mini disk 26-3022...

From: Claude.W <claudew_at_sprint.ca>
Date: Sat Oct 14 23:35:57 2000

>>These are the 1st floppy disks for the COCO made by RS. The units are
>>TEC FB-201.
>>
>>Large full size mounted on their side in silver case with power supply.
>
>>
>>When dskinit (format) command issued, they go about 35 tracks then an
>>error is reported on the COCO screen.
>
>
>You sure it isn't the first drives for the TRS-80? The symptom would be
>the older SA400 drives designed for 35 track operation used within.
>The later drives were SA400Ls that were designed for 40 track operation.
>Both used the spiral groove cam but one was a bit different.
>
>Open up the box and see which you have.
>
>The other possibility is old (really old) media ment for the 35 track
>drives and this media has a smaller "window" in the jacket that will
>limit head travel.
>
>>They can't read a disk formatted on a good drive.
>
>
>That suggests teh head follower is out of the groove or
>the stepper has been rotated or other wear probems.
>
>>These drives use a plastic disc with a "spiral" grove stuck to the
>>stepper motor shaft to step the head along. I have seen this in Apple II
>>drives, it seemed reliable...but I have been told these RS drives were
>>not really realiable...
>
>
>SA400 drives were very poor over time for reliability. You would
>need an alignment disk to set it up or lot of trial and error assuming
>the head moves freely on it guide rails.
>
>Allison

Cant see SA400 anywhere...TEC FB-201 only thing I see...

They have "TRS80 Color Computer MIni Disk" in front of case.

They are listed by catalog no. on COCO web sites as being the 1st drives put
out for the COCO. Problematic but no hints given to fix them...

They don't "look" like they have been used a lot.

Looks like everything is working as far as the "groove cam" is concerned....

If it was wear and "slack" in the groove or other parts , I think I should
be able to have it "track" and do small reads when playing around with the
step motor alignement...no? It look almost like nothing is being written or
read at all...perhaps a failure in the electronics...

Test points are "identified" on the board with abbreviations...I will probe
these out "blindly" trying to figure out what's happening if I get no other
hints...

I am sure there was a service manual for these, RS had a service manual for
almost everything they sold back then including stuff like calculators!...I
actually bought a lot of about 300 at one point and threw them all out after
a few years not using them....

Thanks for the reply
Claude
Received on Sat Oct 14 2000 - 23:35:57 BST