Subject: Re: help! shugart 801

From: "Dwight K. Elvey" <[email-masked]>
Date: Tue Jul 22 11:30:01 2003

>From: Joe <[email-masked]>
>
>    I have several systems that use Shugart 800-1 SS 8" disk drives. I've
>got several defective drives plus I've been wanting some spares. Last week
>I picked up 10 Shugart model 801 SS drives. Today I tried to use them on
>the same systems but I can't make them work. I've set all the jumpers and
>straps exactly the same as in the 800-1 drives but the 801s aren't working.
>The system knows the drive is there and detects the disk being in place and
>rotating and that the drive door closed but the drive never gets the head
>load signal. I'm using the same system, cables, power supply, etc with both
>drives so the only difference is the drives themselves. I've tried a couple
>of 801s and gotten exactly the same results with all of them so I don't
>think that it due to a drive failure. Anybody have any experience with
>these or have a good idea of what's wrong?
>
>   Joe
>

Hi Joe
 You do know that some of the drives have data separators.
I forget which numbers have this and which don't. I don't recall
if the 800-1's had them or not. If you are using these for
M2FM, is seems that I remember that the bandwidth was slightly
increase on these drives. As I recall, there was a capacitor
change in the pre-amps.
 Those are the only things I can think of.
Dwight

---

From: Joe <[email-masked]>
Date: Tue Jul 22 16:02:00 2003

> Those are the only things I can think of.

   You may be right but the head isn't even loading so I'm not even getting
that far. I have a Shugart 800/801 manual but it's vague about the
differences between the two. But IIRC the 801 is designed to handle hard
sectored disk and the 800 doesn't. I'm wondering if the index pulse
detection circuit is different and may be causing a not ready condition or
something similar. (Yes I know I can check it with a logic probe but I
didn't have one where the machines are located so I havne't done that yet.)

     Joe

---

From: [email-masked] (Tony Duell)
Date: Tue Jul 22 17:58:00 2003

> something similar. (Yes I know I can check it with a logic probe but I

I think you might well be on the right track. IIRC, the 'ready' signal 
only goes active after the index signal has behaved correctly (indicating 
there is a good disk, rotating correctly, in the drive). It's possible 
that if the drive is set for hard sector operation and you've loaded a 
soft-sector disk, then the drive will never go ready.

According to the scheamtics, there's a pair of jumpers labeled '800' and 
'801' on older versions of the main PCB. Later versions (with a 40 pin 
ASIC) have a single 3 pin jumper with the 2 positions labelled '800' and 
'801'. This is confusing, you _don't_ set the jumper to '801' if you have 
an '801' drive.

Rather, '800' means soft-sectored (and disables the hard-sector 
circuitry, which is only present in 801 model drives), '801' means 
hard-sectored. I'd check the position of this jumper.

-tony

---

From: Don Maslin <[email-masked]>
Date: Tue Jul 22 18:14:00 2003

> didn't have one where the machines are located so I havne't done that yet.)

Joe, the 800 series OEM manual has a brief table entitled Model
Differences.  It is copied below:

800-1	Soft Sectored with an FM (single density) data separator.
800-2	Spft Sectored without data separator.
800-4	Mechanics only (No PCB)
801	Hard Sectored with an FM (single density) data separator
	and sector separator.

NOTE:
	To convert a 801 to a 800 move the shorting plug from the
	801 position to the 800 position.  A 800 cannot be
	converted to a 801.

						- don