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bettablue
March 19th, 2012, 08:05 PM
:cool: I'm working on the final assembly of the IBM 5161 expansion unit. I have a 30 Meg IBM Full Height MFM hard disk that does not have a face plate. However, I have a faceplate that came from another drive that I can attach with little work. I don't know what kind of drive the it came from, but the faceplate has a green activity LED in the lower right side with a "grid" along the bottom edge with vertical openings. I want to connect that activity LED so that when the drive is in use, the LED is lit. :confused: I guess a better question would be, since the disk drive was initially intended for installation into an IBM 5170, where would the activity light (if any) connect to the hard drives circuitry if at all possible? I tested the LED in the faceplate, and it still works.

According to modem7's web site, it appears that it is a type 0665 drive but the rest of the numbering doesn't make any sense to me. Everything on his site says that my drive should be a 20 meg unit, but it is clearly labeled as being a 30 meg.

There are some photos of the disk drive here I posted in another thread: http://www.vintage-computer.com/vcforum/showthread.php?29604-RLL-Controller-requirements/page2

Look for #13 on the 2nd page

I try to keep exact documentation for all of the hardware I have in all of my computers. The IBM 5150 PC and 5161 Expansion Unit combination is no exception. While I have documentation for all of the other hardware I can find, I am still missing documentation for these hard disk drives. There are some other pieces of hardware too that basic info is missing, but not really required, but right now I just want to focus on the disk drives. I would like to get as much info as as possible for the full height 30 Meg IBM MFM hard disk drive, and the full height Miniscribe 2012 MFM that is already installed into the expansion unit too if at all possible. I do have a spec sheet for the Miniscribe, but nothing on the IBM drive. I guess I'm looking for some PDF files or documents to include in my system resources folders.

As usual, your help in this very minor issue id greatly appreciated.

Thanks again. :)

SpidersWeb
March 19th, 2012, 08:14 PM
How did you get on with the controller? Does your Xebec support 30Mb drives?

And I beleive the LED usually connects to the front of the drive usually, and it's on when the drive is activated (normally) rather than an access LED (at least from my experience with MFM that's how it is).

Edit: Looking at the photo, its a 30Mb IBM AT Type 20 (733 cyl, 5 heads).
Edit2: site doesn't say it's 20Mb, it says it' s a Type 20 - http://www.minuszerodegrees.net/5170/hdd_type/5170_hdd_type.htm

MikeS
March 19th, 2012, 09:48 PM
None of the pics show the PCB but as SpidersWeb says there's usually a 2-pin connector near the front of the drive. Failing that, most controllers also had an activity LED connector.

bettablue
March 19th, 2012, 10:05 PM
Yep, the Xebec is working fine with the Miniscribe disk. And from what I can tell from the reading I've done, the Xebec controller will support MFM drives up to 70 Megs. The only deciding factor is if it will recognize the IBM drive or not. I'll find out in the next few days or so.

Thanks too for reminding me about the LED connection on the controller. I completely forgot about that. It's in the manual.

Thanks again Mike, Spiders web, and especially Chuck(g) for selling me the controller, among other things...

Just think, I'm almost there! You can all breathe a big sigh of relief, (but not too soon; there's still some work to be done and I have more reasearch to do.)


None of the pics show the PCB but as SpidersWeb says there's usually a 2-pin connector near the front of the drive. Failing that, most controllers also had an activity LED connector.

Chuck(G)
March 19th, 2012, 10:36 PM
On the other hand, if you want to connect a LED to the faceplate of the drive rather than use the controller, there's a way.

If this is the 30MB drive described in the O&A, you should see that U6 is an SN7406 IC. Coming from pin 12 of that IC, you should find a header with 2 pins. The cathode of an LED goes to the pin connected to pin 12 of U6; the other pin is connected to +5, where the LED anode is connected through a 220 ohm resistor. Do not omit the resistor in series with the LED!

Elvi
March 20th, 2012, 02:17 AM
And I beleive the LED usually connects to the front of the drive usually, and it's on when the drive is activated (normally) rather than an access LED (at least from my experience with MFM that's how it is).


Litle off topic but i have some MFM drives that blink when there is activity.

bettablue
March 20th, 2012, 09:23 AM
Sweet. Thanks Chuck. I think the manual titled "OA - IBM PC AT 20MB Fixed Disk Drive" is the one your talking about. Which is still wierd. All of the markings on the drive say it's a 20 Meg drive, but then there is that sticker on the end of the drive that says it's got 30 Megs of storage. Things look familiar and similar in some documentation, but not others. I'll try making the connections as you recommend. If it works, great!. I guess I won't really know what it is until I get it completely installed and configured any way.

Thanks again Chuck.


On the other hand, if you want to connect a LED to the faceplate of the drive rather than use the controller, there's a way.

If this is the 30MB drive described in the O&A, you should see that U6 is an SN7406 IC. Coming from pin 12 of that IC, you should find a header with 2 pins. The cathode of an LED goes to the pin connected to pin 12 of U6; the other pin is connected to +5, where the LED anode is connected through a 220 ohm resistor. Do not omit the resistor in series with the LED!

bettablue
March 20th, 2012, 09:29 AM
I didn't see a 2 pin connector while doing a predurory look at the drive, but I'm going to remove the screws holding the circuit board to the drives chassis. I'll look under there. If I don't find it, then I'll try Chuck recommendation. And as far as Elvi's comment, I thought all drives with a face plate attached had some sort of activity light or, lacking a front faceplate as required by the early IBM systems, an activity LED on the case. It just so happens that this drive didn't have a faceplate by default. But it will when I'm done.



None of the pics show the PCB but as SpidersWeb says there's usually a 2-pin connector near the front of the drive. Failing that, most controllers also had an activity LED connector.

MikeS
March 20th, 2012, 09:35 AM
All of the markings on the drive say it's a 20 Meg drive, but then there is that sticker on the end of the drive that says it's got 30 Megs of storage. Well, from what I can see in the pictures I gotta go with SpidersWeb again, that the 20 is the AT type, not the capacity. See post #2 again.

pearce_jj
March 20th, 2012, 09:40 AM
According to an earlier thread, there were 3 varients of the 0665:

http://www.vintage-computer.com/vcforum/showthread.php?16229-IBM-Hard-Drive-type-0665

Type 38 is 30MB, according to that.

Chuck(G)
March 20th, 2012, 09:41 AM
My advice came from the O&A 30 MB drive section, not the 20. A photo of the drive PCB would clear a lot of misunderstanding up. If it's the original 20MB, then the activity LED pins are 1 and 2 of J9.

MikeS
March 20th, 2012, 09:51 AM
According to an earlier thread, there were 3 varients of the 0665:

http://www.vintage-computer.com/vcforum/showthread.php?16229-IBM-Hard-Drive-type-0665

Type 38 is 30MB, according to that.Well, the label says 0665, underneath that it says -38, the size is clearly marked as 30MB, and as it was on many MFM drives it's almost certain that the big number 20 is the type, so I really don't see the problem.

Stone
March 20th, 2012, 10:08 AM
I have one of these drives and everything MikeS says is correct. Furthermore, the *only* pins are for DS. There are no LED connector pins.

Chuck(G)
March 20th, 2012, 10:23 AM
A PCB photo will still be nice. In any case, the activity LED on the one I'm looking at (and this also goes for the 20MB drive) is simply derived from Drive Select using a pair of inverters--the first to invert the active-true DS signal, the second as an OC driver for the LED.

Stone
March 20th, 2012, 10:48 AM
The PCB is flat and covered by a piece of insulating paper that is screwed on. When you remove the paper you can see there is nothing but a flat, soldered board with no components, connectors or anything on that side, whatsoever. The drive Select is between the power connector and the MFM control connector on the back of the drive where an LED connector wire would need to be 12", just to be in the right neighborhood.

Chuck(G)
March 20th, 2012, 10:52 AM
So what's on the other side of the PCB?

Stone
March 20th, 2012, 11:11 AM
All the components. :-) But the only area accessable is the back of the drive i.e., molex connector, 2 MFM card edge connectors and a 5 position DS jumper block. Like I said before, do you think the LED activity connector could be on the back of the drive, 12" away from the case? I hope you're not thinking position 5 on the DS block is it. :-)

Here, have a look:

http://www.recycledgoods.com/zoom.aspx?productID=7960

Chuck(G)
March 20th, 2012, 12:59 PM
No, but it's the rare 5.25' drive that doesn't have somewhere to attach an indicator LED. It would be very informative to see the component side.

Stone
March 20th, 2012, 01:38 PM
I've taken the logic board off of several FH doorstops lately but I won't disassemble this drive to inspect it 'cause it WORKS!!! :-)

bettablue
March 20th, 2012, 01:58 PM
No, but it's the rare 5.25' drive that doesn't have somewhere to attach an indicator LED. It would be very informative to see the component side.

Well, that won't happen. I just got an offer I couldn't refuse and I sold eht drive today. I actually had to go back and remove it from the expansion unit and put the faceplate back on the "cage" I bought from stone.

Oh, well. I'll look for another drive I know will work. There is no hurry at this point.