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Old 09 May 2008, 23:18   #1
Yoto
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Research on Micronik HD 1.76 MB Power M-disk

I bought this drive 9 years ago for my Amiga 1200 and used it until a few days ago...
A bad Disk rammed the top head off...

Anyway i found out that this is a Sony MPF 920-E/131 Drive with some tweekie Lattice semiconductor chip, the GAL16V8B (PLCC) Type.
10 wires connect this chip to some key points in the Drive PLC.
I believe one can reproduce this in a Sony Drive, not sure if it must be from the 131 series.I can upload a few pictures if this interests anyone out there.

I modified an old Sony 420-4 to work with my 1200, it works great, appart from the fact that X-Copy cant recognize the disks, for some reason;well it couldnt recognize 1.76 mb disks too, but it was a nice way to format and verify 880K disks.
I have a lot of 1.76 mb backup disks that i cant open now...

BTW, Does anyone knows why X-Copy recognizes the drive but cant find the disks?
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Old 10 May 2008, 01:10   #2
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Quote:
Originally Posted by Yotoxionomai View Post
I bought this drive 9 years ago for my Amiga 1200 and used it until a few days ago...
A bad Disk rammed the top head off...

Anyway i found out that this is a Sony MPF 920-E/131 Drive with some tweekie Lattice semiconductor chip, the GAL16V8B (PLCC) Type.
10 wires connect this chip to some key points in the Drive PLC.
I believe one can reproduce this in a Sony Drive, not sure if it must be from the 131 series.I can upload a few pictures if this interests anyone out there.

I modified an old Sony 420-4 to work with my 1200, it works great, appart from the fact that X-Copy cant recognize the disks, for some reason;well it couldnt recognize 1.76 mb disks too, but it was a nice way to format and verify 880K disks.
I have a lot of 1.76 mb backup disks that i cant open now...

BTW, Does anyone knows why X-Copy recognizes the drive but cant find the disks?
Don't know about the unit, but just a single tip for Xcopy: did use the killsys before use the program?
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Old 10 May 2008, 21:54   #3
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Thank you rkauer for your quick reply!
Yes i did, still it displays the same unpleasant message,... "No disk in Df0:"
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Old 11 May 2008, 17:18   #4
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Quote:
Originally Posted by Yotoxionomai View Post
Thank you rkauer for your quick reply!
Yes i did, still it displays the same unpleasant message,... "No disk in Df0:"
Have you been able to locate another onf of these same model Sony Floppy Drives ?!?

If so, then carefully unscrew the circuit board and swap it onto the new floppy drive.

The only thing you have to really be extra careful with is the flat, flexible cable that connects the top and bottom R/W heads to this board.

Obviously if the same model floppy drive can't be located then a hacking job is in order, good luck to you on this one
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Old 12 May 2008, 16:05   #5
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Thanks jmmijo for you help!
I cant find a MPF920-E /131 model around here,i´ve searched every hardware store and Ecocenters...still no go!
The closest match i found is a new Sony MPF920 , there are quite a few diferences in the board PCB from the early E series (1998), the older one has a jumper area close to the stepper motor flat cable, but the chassis is the same, so i hope to merge the old PCB into the new drive with little trouble, my only doubt is the compatibility between the heads, and the stepper motor, they do look the same though.

Last edited by Yoto; 12 May 2008 at 19:23.
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Old 13 May 2008, 07:33   #6
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So can any other HD Floppy Drive work in this unit ?!?

Does this use an interface card inline with the data cable to adjust the data density or is it like the CBM drives that actually spin at half speed ?!?
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Old 13 May 2008, 14:33   #7
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No Jimmijo, no interface card , thats the beauty of the thing , it relies solely in a small Lattice chip, the GAL16V8B, that steals the HD signal from the cable interface solder points and then increments it directly into the PCB. I was trying to replicate this MOD by using this same chip, not only to recover my drive, as well as to make it available to all amiga users.
The new Sony MPF920 is too different from its previous versions, i am trying to find a MPF920-E review 131 (1998-99) the 2000 to 2003 version is almost the same as the actual MPF 920 , but the smaller chip is quite different from the original, in position and number of contacts.
I do believe the heads and Stepper motor are the same, in order to avoid head misalignment, i will keep the newer stepper motor, and heads, i will unsolder these two from the new PCB and replace it with the old one.
If anyone as any experience or knowledge in this kind of mods i will be most gratful for all the help!
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Old 13 May 2008, 17:38   #8
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I have with me one of these drives which I got off ebay quite expensive, and it did not work. It doesn't even recognise DD floppies. I was too lazy to follow up with the seller lol, I told them it didn't work, then I didn't get back to them.

Maybe I can help you by finding the model of my floppy drive inside, and fix mine at the same time. Do I need to unscrew all of the many screws on the bottom? (taking off the top cover does not reveal the drive model that I can tell). I don't want to remove the wrong screw and end up with a mix of lego pieces. I think it would just be to unscrew the 3 screws around the edge of the frame?

EDIT: Just noticed on a sticker it says "9808 E/131", so it must be the same Sony MPF 920-E/131. Also it appears obvious that someone had already opened the drive as the cover is a bit loose on one side.
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Old 13 May 2008, 18:59   #9
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Yes Calgor, its the same bloody thing, i´ve managed to fix mine, i´ve acquired a new Sony MPF920 just today, and i´ve cannibalized the thing, first i unsolded the stepper motor flat cable ,then the Head Sensor...its a bit tricky, but they are fully compatible with the older PCB Modded by Micronik.

If anyone out there wants to do it to your drive you may want to read the following steps, read it fully and carefully, and apply them at your own risk. Before doing it consider if you have the necessary skills and tools, also check below in the "Other important things you should have in mind" before do anything that you may regret later.

Exchanging MPF920-E /131-Micronik chassis with MPF920 (Drive Heads, Head Sensor and Stepper Motor)
(Disconnect both head cables from the PLC)

Make sure you use a small clamp to lift the stepper motor pins from below,while you aplly a low temperature solding iron, be careful not to lift it while the sold is still cold, you may damage the circuit below,if that happens you will have to bypass it to the resistences ahead or expose a little of the circuit.

Lift it pin by pin slowly!!!

Low Temperature Solding Iron is really important, cheap solding irons sometimes have live fase and high temperatures that will damage the components.
You will have to do this operation twice.

One for the Stepper Motor and other for the Head Sensor flat cable on the opposite corner.

You may want to use a 3 volt test lamp to check on the solded components, i always do that.
It may look well solded but sometimes its not, check it by following the circuit from the Stepper Motor contacts to the nearest opposite naked contacts after the area you just solded.

Other important things you should have in mind:

Make sure you glue some paper tape below the Lattice Chip inside the drive, otherwise the contacts may short circuit with the metal cover,and that may well be the reason why your drive does not work properly, also check to see is all its wires are connected to the right place, if they are not and you are not sure where the right places are, i can post a picture i took from my drive.

Check the stepper motor axis and see if its not too dirt, if it is, use a small soft brush to clean it. (Dirty Stepper Motor axis will make the drive fail to read / write and format Disks to the endtrack)

Check the Heads for dirt too, old disks tend to "dirten" the head too often, and faster than you can imagine, since cleanning disks are a rarity nowadays you may want to look for other ways to get the heads cleanned.
First dont lift the upper head, just use a poorly wet Cottonet and gently circle it around the lower and upper head.(Use water , and only water...saliva also seems to works well...)

Whatever happens NEVER lift or unscrew the upper head, nor remove the stepper motor, nor unscrew the bolt that adjustes the Head Sensor metal plate.( I learned this the hard Way) LOL.

Good Luck! I hope this helps...somehow...

Last edited by Yoto; 14 May 2008 at 01:02.
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Old 14 May 2008, 08:21   #10
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Whoosh.... all that went way above my head. Thanks heaps for the tips if only I had the skills.

I have no idea between the stepper motor or whatever. I do however have a floppy cleaning disk (these are quite plentiful on ebay if you need any). I will try that and see if it improves anything.

I just have an el cheapo soldering iron, and my skills are almost non-existent, so I couldn't do those tasks. Was hoping there were somethings I could check without soldering, but sounds like to check those I need to unsolder some things first.

I don't think it gave the clicks waiting for the floppy to be inserted. Does your drive give these clicks or is it silent?

Also, the top of my drive seems curve in slightly - the thin sheet of metal at the top of the drive dips in the front-centre about 2-3mm or so. Is yours totally straight or curved?

Glad to hear your drive now works. Does it work with HD disks too? And it is able to load amiga games that the AT 1200 floppy drives can't?
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Old 14 May 2008, 11:22   #11
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Yes Calgor its fully functional, it also Formats at 1.76 mb and loads all the few surviving disks i have.
No the top its not curved, and yes its makes the clicking sound.
It looks like your drive took a serious bang in the top, but that may yet be fixed.

First you should remove the top cover and check the ejection mechanism, insert a disk into into it a see how the mechanism operates, there´s some kind of white plastic lever that slides the Disk cover open and makes the heads join one against each other with the Disk tape in between.
Now you can remove the Disk and pull the plastic lever down and see if the heads join with each other, they must touch each other.
If the ejection mechanism is ok then the problem should reside elsewhere, if you say that the drive dosent clicks then is probably not recognizing the READY signal and that is most likely in two areas, first it can be the type of flat cable you are using, is it a modified cable , with the 2 swaped with 34? (this is not possibly if you are using the original Amiga Floppy cable) then that leaves us only a second option, for this one you have to remove the bottom cover, unscrew the 3 screws, and check the connections between the Lattice Chip ( 5 pins on each side in the PLCC version ) and the PCB (Drive Board) Remember to see if any of this connections are ok, in the CHIP itself try to see if any of the solded wires fall on the contact next to it , they must all be individual if they touch in the contact next to it use a small clamp and gently move it away from it. Also there´s usually a short bit of Paper Tape on top of this chip, you can remove it and replace it, you can also glue the tape in the bottom cover instead, if you do this make sure you glue it in the right place. A third but not likely problem may also be the switch that activates the drive engine and the Ready signal , its located at the right of the Disk protection switch. To test this , and if al the rest fails to produce some result, you can also identify the switch contacts and bypass them with the use of something metallic like a small clamp or screw driver. I hope this helps further.

Last edited by Yoto; 14 May 2008 at 11:36.
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Old 14 May 2008, 12:15   #12
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Old 14 May 2008, 12:22   #13
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CUT represents the places where Micronik Bypassed the original circuit in the Sony MPF 920-E /131 Board.
Lower Cut Is just a 2-34 swap, and must include another circuit cut in the # 2. As already described by some PC to Amiga Drive modders.
Upper Cut the original Chip Signal was redirected to the Lattice chip in order to reassign the HD Signal.(I think)
I included the Lattice Chip position, for anyone who wants to Mod this Type of Drive.
The Jumpers are Set To DF0:, the original non modded Sony MPF920-E /131 dosent includes Real Jumpers, more info can be found here in this Link:
http://tizeta2.altervista.org/amiga/.../mpf920-e.html
I also had to Drill a small hole into the PCB to let the extra chassis support pass thru (only in the MPF920 (Z-121)
If this newer model heads and stepper motor is compatible with the older PCB i assume older 920-E are also compatible, and its chassis as no extra support, so no drilling necessary.
Unfortunately i could not find any.
Datasheet for the Lattice Semi GAL16V8B-25LJ (PLCC Type)
http://www.datasheetarchive.com/pdf/1460857.pdf
I dont know if this chip has any Micronik custom programming to work with this drive, further research in this area needed.

Last edited by Yoto; 14 May 2008 at 15:17.
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Old 14 May 2008, 15:17   #14
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Quote:
Originally Posted by Yotoxionomai View Post
Datasheet for the Lattice Semi GAL16V8B-25LJ (PLCC Type)
http://www.datasheetarchive.com/pdf/1460857.pdf

Is that GAL read-protected?
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Old 14 May 2008, 15:31   #15
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If you refer to the PDF then...its not, at least not on this end.
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Old 14 May 2008, 19:47   #16
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@Yotoxionomai

Great thread, and thanks heaps for the detailed directions and awesome diagram. Will do those checks this weekend. I suppose if it is not clicking then cleaning the heads with a disk cleaner won't do anything. Will see if my memory was correct on this.

I was using the original A1200 (commodore motherboard version) floppy cable, with which a 880k drive works perfectly.
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Old 14 May 2008, 23:36   #17
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Quote:
Originally Posted by Yotoxionomai View Post
If you refer to the PDF then...its not, at least not on this end.
Nope, I'm referring to the chip itself.

If the protection "fuse" is "closed" (in truth, the GAL don't have a fuse, it's just a protection bit).

Very easy to read the contents and make a lot more of those HD units.
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Old 15 May 2008, 13:20   #18
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That would be great rkauer, but thats beyond my skills with normal tools; I guess one requires some kind of software with a chip programming gadget capable of chip copy, or maybe one could use a normal GAL16V8B-25LJ ?
If you would be so kind to continue this research in that field, and point us in the right direction, i believe i can thank you in behalf of this comunity, in our join efforts to keep Amiga alive.
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Old 16 May 2008, 03:30   #19
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Quote:
Originally Posted by Yotoxionomai View Post
That would be great rkauer, but that's beyond my skills with normal tools; I guess one requires some kind of software with a chip programming gadget capable of chip copy, or maybe one could use a normal GAL16V8B-25LJ ?

If you would be so kind to continue this research in that field, and point us in the right direction, i believe i can thank you in behalf of this community, in our join efforts to keep Amiga alive.
It requires the GAL software (not really needed, only the burning program will suffice) and a serial or parallel port (and the burner, of course).

Remember: "bit" is a word used in the computer world, like in:

"Burning" units will cost a bit...
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Old 11 June 2008, 04:47   #20
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I have a Sony MPF-920E/131 right here.. the same as used in that Micronik device.

Someone local has a "broken" ICE EPROM programmer that I might be able to have; I think it might also burn PAL's.. ?
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