3-pin jumper on Tandon floppy drive?

[musicforlife]

I have 4 Tandons and one of them seems to contain this 3-pin jumper in the backside while all of the rest are having only empty soldered spots there. What was the function of this jumper?

 

[Dwight Elvey]

It looks to only have one pin in the connector. I'd say it wasn't a jumper but a location to connect a test cable. Since it is on the motor control board, I would suspect it is used to look at the motor speed. It maybe looks at the control voltage range or something. The connector on it is to keep one from accidentally bumping and shorting the pins. It is not a shorting jumper.
Dwight

 

[jlang]

I think thats where the door closed microswitch connects (if equipped)

joe

 

[modem7]

On a TM100-4 that I have, the connector at that position has all three pins, and three wires head off to a 'door open/closed' microswitch. Photo follows.

On a TM100-2A that I have, there is no connector at the position, the position labelled as J14 on the PCB.
J14 pin 1: On PCB, connected to the positive via of position CR1. No diode in CR1 fitted. Also connected to the positive via of position CR3. No diode in CR3 fitted.
J14 pin 2: On PCB, connected to the negative via of position C7. No capacitor in C7 fitted. Connected to nowhere else.
J14 pin 3: On PCB, connected to +12V

 

[Dwight Elvey]

That is what they are for then. The one that was shown had no wires and likely had no door switch.
It is clear that it is for a door switch and not a test point, as I suggested.
Dwight