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Help with power supply for Mitsubishi Model M2896 8" Drive

Jimmy

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Feb 19, 2012
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Fort Walton Beach, Fl
I have a model M2896 Mitsubishi 8" diskette drive, I have the following setup below.

I have a DBIT power adapter and a DBIT 50 to 34 pin cable adapter. On Chuck G's advice I have tried to operate the Drive with an Adaptec Drive with a floppy controller, Sergey's FDC controller board as well as an XT-FDC board from the forum. All of them work.

I am trying to assist a friend who is trying to setup the same basic configuration with a Shugart 851. He is hoping to find a less inexpensive option that the DBIT adapters. I found a 50to34 PCB that think will work.

Can I use a MEAN WELL AC-DC Power Supply Dual Output 5V 24V, that you find on Amazon, with the correct connector for the Shugart Drive.


Thanks,


Jimmy



8InchDrive.jpg
 
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Looking up the power requirements for the SA851, I see 1 amp for the 24V and 1.1 amp for the 5V. If the supply you are looking at is rated for that or more you should be OK.
Dwight
 
I've also used a standard 5+12 VDC supply with a separate 24V supply. In any case, it shouldn't be too hard--there were lots of open-frame 5+24V supplies in the day.
 
I've also used a standard 5+12 VDC supply with a separate 24V supply. In any case, it shouldn't be too hard--there were lots of open-frame 5+24V supplies in the day.
Yeah, I've also got a few of those but when the system is a PC or otherwise with an AT/ATX supply with lots of amps then the $4.00 converters are very convenient.

I've got a 400W ATX supply in an S100 box to power two ST-4096s and the floppies, including the TM848 using one of those.
 
Looking at the SA851 schematic, the 24V is only used for the head load solenoid and the stepper power. I suspect it could be done with a simple transformer, rectifier and filter capacitor. No need for a regulator. A reasonably large capacitor ( about 2,000 uf for about .25V P-P on 60hz full wave ) is needed. I see 2 amp 18Volt transformers on ebay for under $13.
 
Looking at the SA851 schematic, the 24V is only used for the head load solenoid and the stepper power. I suspect it could be done with a simple transformer, rectifier and filter capacitor. No need for a regulator. A reasonably large capacitor ( about 2,000 uf for about .25V P-P on 60hz full wave ) is needed. I see 2 amp 18Volt transformers on ebay for under $13.

..hmmm... If the current drain on the 24V supply is about 1.1A there would be too much ripple with a 2000uF cap...I think. But I guess the load is not there constantly.

Going back to first principles, Q= CV for the capacitor, then dQ/dt = C dV/dt. If one assumes that the ripple decay is almost linear between peaks for a 1v out of 24V step, and its a full wave rectifier, where the capacitor is being recharged every 8.3 mSec (on a 60 Hz system), and say you were prepared to put up with a 1 volt ripple between the peaks that are 8.3 mSec apart, then dQ/ dt = 1.1A = C x 1v / 0.0083 sec, solving for C yields 0.0092 F = 9200uF. So the calcs suggest it should be something like a 10,000uF capacitor, if the current drain is around 1A and you don't want anymore than about 1V of ripple.
 
..hmmm... If the current drain on the 24V supply is about 1.1A there would be too much ripple with a 2000uF cap...I think. But I guess the load is not there constantly.

Going back to first principles, Q= CV for the capacitor, then dQ/dt = C dV/dt. If one assumes that the ripple decay is almost linear between peaks for a 1v out of 24V step, and its a full wave rectifier, where the capacitor is being recharged every 8.3 mSec (on a 60 Hz system), and say you were prepared to put up with a 1 volt ripple between the peaks that are 8.3 mSec apart, then dQ/ dt = 1.1A = C x 1v / 0.0083 sec, solving for C yields 0.0092 F = 9200uF. So the calcs suggest it should be something like a 10,000uF capacitor, if the current drain is around 1A and you don't want anymore than about 1V of ripple.

My bad
I divided instead of multiplying. Still, 10,000uf is reasonable. All the loads are inductive and that should help some.
Dwight
 
Yes, you can use Mean-Well switcher modules. That's how I've got my Xerox 8" drive cabinet powered at the moment. They'll also current limit in the event of a short in the drive (if the model you get supports that).
 
I've not bought a Mean-Well supply specifically for 8" drives, I just have a bunch of them around the shop from other equipment. I'm using a 24V module and a +/-5V module. It'd be nice to get a part # for something that does all three!
 
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