Shugart 801 “L” Jumper Question

[Peter Sterrantino]

Hi All, 

Getting around to setting up this Shugart 801 with my IMSAI and Mikes FDC+ board and I have questions about the “L” jumper (shorting plug) on the board. 

The manual says under ***: 

The text describes “horizontal” or “vertical” positioning of the jumper. I’m supplying -5VDC so I believe I need the “horizontal” position but not sure what that is in reference to.  Is horizontal simply the jumper installed (shorted)? 

My drive board was missing that jumper and looks like the pics below. 

Also wondering what basic power up behavior looks like. When I power up, the drive spins (as I expect), but nothing else happens…. I think I was expecting some zeroing of the stepper motor or something. 

Thanks, Pete 

[Joseph Corda]

Pete ..

I have not messed with my 801 drives yet, so I can't offer any advice
Hopefully someone with 801 experience will chime in,  if not you can also try to post on the S100 forum  ..

Joe

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[Peter Sterrantino]

Hi Joe, 

Thanks. I was focusing on the Shugart manuals, but Mikes FDC+ document says this: 

Not perfectly clear, but it sounds like for a -5V supply you install the jumper. 

Pete

[Mike Douglas]

The L jumper is confusing because it’s marked differently on different versions of the PCB. On your PCB, install the jumper for a -5v supply. Remove the jumper for a -7 to -16v supply. You can know it’s configured for -5v if pins 2 and 3 on the 7905 are shorted to each other.

Mike D

[Mike Douglas]

Speaking of ambiguous… the assignment of pin numbers to the TO-220 regulator package is not consistent, so let’s say you can tell it’s configured for -5v operation if the input pin (center pin) is shorted to the output pin (pin on the right when the part is oriented with the metal tab at the top, the pins at the bottom, and the metal tab at the back of the part body).

Mike D

[T Gerbic]

Just a jumper for VR1 if you don't need it (when -5V is used). 

[Mike Douglas]

Tony,

The purpose and mechanism for the L jumper is clear, it’s how it’s marked and used on different board revs that’s confusing. So yes, as I mentioned, you can verify you’ve got the jumper L set right for -5v operation by checking that Vin on the regulator is shorted to Vout (regulator bypassed).

Mike D