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Time to start repair on my single sided 160KB Floppy drive..

VERAULT

VERAULT

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So In an effort to finish my restoration on my early model 5150 I think its time to address the single sided 160KB floppy drive (or is it 180KB? Half of 360kb right?) Going to test for shorts but I noticed that the IC socket where there is normally a jumper block bridging pins 3 and 14 there is nothing. Should I still add something to short pins 3 and 14 for single sided use on Dos 1.5?

I have it circled in RED in the photo as IC position 1E.

By the way does anyone have a working 160KB single sided drive working in thier 5150? It would be nice to have questions answered on disk imaging.

IMG_20220928_154600.jpg
 
Tthe simple thing I do is plug a 8 position dip switch into the 1E Position. That way you can select
exactly what toggles to short.

Larry
 

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VERAULT said:
the single sided 160KB floppy drive (or is it 180KB? Half of 360kb right?)
Click to expand...
That depends on the version of DOS. I think it's DOS 1.1 added support for double sided, and DOS 2 added support for 9 sectors per track, so 180K or 360K, vs the previous 160K or 320K with 8 sectors per track.
 
VERAULT said:
Going to test for shorts ...
Click to expand...
The only reason you would do that is if the drive was causing the power supply to shut down.
If there is a short, then see the 'Short-circuit capacitors' section of [here], because there is a history of two particular tantalum capacitors being problematic.
 
Thanks for all your help everyone this is great info.

@modem7 the only reason I do that is because in the past 2 years I started getting tantalums on these floppy drives failing.. and like you said shorting the psu out. My Kaypro 2 for instance had it happen earlier this year. Same drives in it.
 
If you are troubleshooting a single drive on the Cable is the TERMINATOR Resistor Installed?
Does the Drive LED come ON when the Drive is Selected?

If the Terminator (PULLUP RESISTOR PACK) is installed there is only IC's 2B & 4F to troubleshoot,
assuming the +12VDC, +5VDC and GND is applied to the Motor Connector.

Larry
 
So I checked 2B and 4F (7406 and 7438) both ICs test fine. I also replaced the tantalum at C43. The drive still does not spin.
 
I think that bitsaver manual says it’s a tip110, if I’m looking at the correct schematic.

Edit: Assuming the double sided drives are the same. Is this what you’re looking at?

92B486EE-0BB0-4F79-8B4E-D3290904CEEC.jpeg
 
Thanks Both. Seems its a tip110. But I was barking up the wrong tree. ITs definitely the speed board as a swap from another drives I get the motor spinning. But the q1 is not the culprit.
 
VERAULT said:
Thanks Both. Seems its a tip110. But I was barking up the wrong tree. ITs definitely the speed board as a swap from another drives I get the motor spinning. But the q1 is not the culprit.
Click to expand...
U1 is also known to fail. It's an LM2917 voltage/frequency converter.

If there is anything wrong with the actual motor (i.e. it won't maintain speed even with a good driver board) I have some extras I could sell you one
 
Speaking of drive speed I am not acustomed to checking and changing drive speeds on a PC system. Can I use a program like imagedisk to check and set drive speed?
 
Yes, just keep in mind that the speed test in IMD averages the totality of the time it has been running. After you make an adjustment you need to hit the space bar to reset the counter
 
Is there a more comprehensive program?
I have my doubts about a certain adjustment pot not working. When I turn it the drive speed does not sound like its increasing or decreasing RPM

just curious, what is the ideal drive speed for one of these drives?
 
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Ok so I took the drive motor/speed board from a good working drive to test the single sided drive. Now I am putting it back on the 360KB drive and its not reading disks and sounds too fast. Yeah I made the bonehead move of adjusting the pot. IMG_20221004_171242.jpg

Im getting weird errors and 7601 RPM sounds wrong to me.. But the drive seems to be running the wrong speed which probably accounts for the not reading disks correctly or being able to format a disk at all. Could the pot be bad and just moving it broke it?
 
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