Date : Thu, 14 Feb 1991 03:05:04 GMT
From : mvb.saic.com!ncr-sd!simasd!simasd!pnet07!donm@ucsd.edu (Don Maslin)
Subject: Help: 8" SA-851 Failure. Where to send for repair?
mbeck@ai.mit.edu (Mark Becker) writes:
>Problems.
>
>My S-100 work has just come to an abrupt halt by the failure of both
>Shugart 851 8" floppy drives. One lost head #2 (the head that is on
>the head-load lever) some time ago, the other lost it two days ago.
>
>I find that if apply a light pressure on the heads then I can boot the
>system.. but this is obviously non-optimal.
>
Assuming that dirty heads are not the problem, have you lost the spring that
loads the upper head?
>Questions:
>
> * I need references to repair places. Where have YOU sent
> 8" drives for repair?
>
Can't help you there. Likely you have a do-it-yourself project.
> * Does anyone have a manual for this series drive that has a
> description of all the jumpers and what they do? Maybe an
> OEM manual with schematics?
>
Perhaps the following will be of some help.
Customer Cut/Add Trace Options
___________________________________________________________________________
TRACE SHIPPED FROM FACTORY
DESIGNATOR DESCRIPTION OPEN SHORT
5E Terminations for M'plxd Std Inputs H Plugged
DS1 Drive Select 1 Input pin Plugged
DS2,3,4 Drive Select 2,3,4 Input Pins X
1B,2B,3B,4B Side Select Option Using Drive Select X
RR Radial Ready X
RI Radial Index and Sector X
R(SHUNT 4F) Option Shunt for Ready Output X
2S Two-Sided Status Output X
850/851 Sector Option Enable 850 851
I(SHUNT 4F) Index Outpur X
S(SHUNT 4F) Sector Output X
DC Disk Change Option X
HL(SHUNT 4F) Stepper Power From Head Load X
DS Stepper Power From Drive Select X
WP Inhibit Write When Write Protected X
NP Allow Write When Write Protected X
D Alternate Input In Use X
M MulZ:Z-Media Option Plugged
DL Door Latch Option X
A,B,X(SHUNT 4F) Radial Head Load X
C Alternate Input Head Load X
Z(SHUNT 4F) In Use From Drive Select X
Y In Use From Head Load X HC*L&#xSide
Select Option Using Direction Sel X
S2 Standard Side Select Option Plugged
S3 Side Select Option Using Drive Select X
TS,FS Data Separation Option Select TS FS Plugged
IW Write Current Switch Plugged
RS Ready Standard Plugged
RM Ready Modified X
HLL Head Load Latch X
IT In Use Terminator Plugged
HI Head Load or In Use to the In Use Ckt X
F (MLC10 only) Remove for MFM encoding. Instl for M2FM X
AF(MLC11 only) Install for FM or MFM encoding Plugged
NF(MLC11 only) Install for M2FM encoding X
There is a DIP 'Shunt pack' at location 4F to select drive number and
other options as indicated above. Also, at location 5E is a DIP socket
for a terminating resistor pack. It appears to be simple 150 ohm per
resistor type rather than a 220/330 ohm divider.
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