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26 Pin Hard Disk Connector

Thx1138 said:
Jeez, I missed that too Mike, sorry, I've also amended my blog entry.

Charlie
Click to expand...
No, I'm sorry; I didn't mean to sound serious and was just teasing you guys, but the smiley didn't make it for some reason.

Not gonna help much though if/when the old ones die; that interface sorta looks like a modified floppy interface, nothing like ST-506, IDE, or SCSI.
 
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Cheers Mike, I know how annoying it can be, lol.

I think you're right about the modified floppy interface as the socket that the daughter card plugs into looks like a floppy one to me.

On the subject of floppy drives, the PX-16 has an SMD-400 in it which I can't get to work, it fails on all disks and when I try to format one it just comes back with Invalid media or track 0 bad.

Frustratingly I can't swap it out because it doesn't have a regular power connector, it takes its power via the interface cable and I don't have any other drives likes that, are they common?

Does that error on formatting point to any particular issues with the drive, head alignement, motor speed etc?

Charlie
 
Hi, I've opened the drive up and oddly there's a cabled that's soldered to the board at one end but nothing at the other, any ideas?

The head seems to move backwards and forward smoothly, I need to get something to clean it with, but that cable's bugging me, my instinct says it looks like it's been added after assembly, but if it's an integral part of the drive I can't really understand how it has become detached?

20110714-img_1962-1.jpg


Cheers,

Charlie
 
In my PX-16 boxes here is still stuff to try/document/repair: two new dual floppy units, several harddisks fro defunct Epson Equity LT (same 26-pin connector) and even an extra PX-16 base unit, but this one isn't working for sure. I could try to take apart one of those floppy unit floppies to find out more about the connector.

All the non-vintage activities take up all the time these days :-(
 
FWIW, we discussed Haemogoblin's Sharp PC-7200 on IRC the other week and made references to this thread. That machine also has a 16-pin connector for internal HDD, but as he didn't have a matching drive or cable, he installed an 16-bit IDE interface instead. I own a Data General One Model 2T that also supposedly supports a hard drive. I haven't looked inside and the amount of online documentation is sparse, but I wouldn't be surprised if it shares the JVC interface.

While doing research, I came across an untested 20 MB (?) JVC drive on German eBay listed at 1 Euro but I never followed up if it got sold and for how much. Perhaps someone was making a bargain if they're a bit hard to find and the drive still would work.
 
Opened up a Disk Unit Type-2 (dual floppy) and then one of the SMD-400's.
This what I found out:
- 3.5", 720 kByte/1.2 MByte, 80 Trk. (from system guide)
- 34 pin connector
- single +5V power supply
- +5V on pin 9 and 11
There is room on the PCB for a standard 3.5 power connector, but it isn't there. Without exactly seeing where Charlies extra cable is soldered to, I guess it is a replacement +5V.

On the hard disk side, I made some images of an 26-pin hard disk from an Toshiba T-3100: http://fjkraan.home.xs4all.nl/comp/divcomp/26pinHD.html
 
Just out of interested, so far I've come across the following machines which use the JVC hard drives with 26pin interface...
GRiDCase 3 Plus
Toshiba T3100
Data General 2T
Wang WLTC Laptop
Sharp PC-7200

Also I think I had a Toshiba T1200 at one time with a JVC drive.
 
Moonferret said:
Just out of interested, so far I've come across the following machines which use the JVC hard drives with 26pin interface...
GRiDCase 3 Plus
Toshiba T3100
Data General 2T
Wang WLTC Laptop
Sharp PC-7200

Also I think I had a Toshiba T1200 at one time with a JVC drive.
Click to expand...
It would be nice if someone was able to build a JVC hard drive emulator for all those folks with these machines, or at least some way to interface the 26-pin to ST506 or some other more common and still available (even if its vintage) hard drive, with all the speculation that these drives speak ST506, it might just be a simple cable adapter, which should be easy.

I have done custom cables adapters before, they are fairly easy (though time consuming), I did one from the Mac Portable's 40pin combined SCSI/POWER to Standard 50-pin SCSI plus 4pin molex to allow it to use any SCSI hard drive.
 
I think a couple of Epson models should be added to Moonferret's list. Eventually that sort of info should go into the VC wiki, once confirmed they indeed use the same interface. I seem to remember the Schneider EuroPC also has a 26 pin connector but I think in that case it is only used for external floppy drive.

Of course another matter is which capacities, number of heads and cylinders each machine supports in case the JVC drives came in more than one model.
 
fjkraan said:
Opened up a Disk Unit Type-2 (dual floppy) and then one of the SMD-400's.
This what I found out:
- 3.5", 720 kByte/1.2 MByte, 80 Trk. (from system guide)
- 34 pin connector
- single +5V power supply
- +5V on pin 9 and 11
There is room on the PCB for a standard 3.5 power connector, but it isn't there. Without exactly seeing where Charlies extra cable is soldered to, I guess it is a replacement +5V.

On the hard disk side, I made some images of an 26-pin hard disk from an Toshiba T-3100: http://fjkraan.home.xs4all.nl/comp/divcomp/26pinHD.html
Click to expand...

Someone gave me another SMD-400 and this one was different to my original one in that it did have the regular additional power connector and a standard floppy interface.

So it seems there are different flavours of SMD-400. No good for me of course although Nikos added this very useful comment to my blog regarding modding a standard FDD:-

http://retrocosm.net/2011/07/14/who-are-you-calling-fugly/#comment-156

Charlie
 
carlsson said:
FWIW, we discussed Haemogoblin's Sharp PC-7200 on IRC the other week and made references to this thread. That machine also has a 16-pin connector for internal HDD, but as he didn't have a matching drive or cable, he installed an 16-bit IDE interface instead.
Click to expand...

Really? I've studied the service manual schematics. That's not what I get. There's a small board with a Z80 CPU and other LSI ICs that installs and then drives a bog-standard MFM drive. H. doesn't have the HDD controller board.
 
Chuck,
Its been a few years since I got rid of my PC-7200 but I'm almost certain it was one of these JVC drives. Certainly didn't have two cables like a standard MFM drive. Is it possible there were different options?

Just a few more details on the drive models...
GRiDCase 3 - 10Mb - JD-S3812M0R0
Data General 2T - 20Mb - JD-S3824R0D0

Will have a look inside the Wang Laptop once I get my hands on it next week.
 
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