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Help with power supply for Mitsubishi Model M2896 8" Drive

Jimmy

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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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Dwight Elvey

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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
 

Chuck(G)

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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.
 

MikeS

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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.
 

Dwight Elvey

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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.
 

Hugo Holden

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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.
 

Dwight Elvey

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..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
 

glitch

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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).
 

glitch

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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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