Oregon Osborne 1 Restoration

[Charrisa]

Alright so I recently got my first vintage computer, collecting has been something I've wanted to do for a long time now and I finally can. This will be my first restoration ever so please do excuse any loftheadedness on my part. The Osborne I've obtained has a non-functional A:> drive, and a broken keyboard. If I can get the keyboard functional then I should be able to boot off of the B:> drive. Dallas has helped me a lot, as well as Sark via the IRC. I'm going to get my hands on a multimeter very soon and test the keyboard to see if any of the keys are stuck on.

 

[JDallas]

Here's my keyboard matrix notes... I think the tech document had errors as I saw no PERIOD key:

On the computer side, chips used to read the keyboard are:
1	81LS95	UE12		(input)
2	74LS05	UE13, UE14	(output Row X LOW Open Collector)
1	ResNet	RN10		Pullups to +5VDC on Column 0-7
1	CONN	P4		Electronics module keyboard connector.

No electronics in the keyboard module:
PIN	SIGNAL		coNNECTOR P1:
01	GND
02	Row 4
03	Row 0
04	Row 3
05	Row 6
06	Row 2
07	Row 5
08	Row 1
09	Row 7
10	Column 0
11	Column 1
12	Column 2
13	Column 3
14	Column 4
15	Column 5
16	Column 6
17	Column 7
18	no connection
19	no connection
20	GND


Keyswitch Matrix: (may be documentation error as I don't see a PERIOD key)
   +----+
   | P1 | Col 0   Col 1   Col 2   Col 3   Col 4   Col 5   Col 6   Col 7
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A0 |  3 |  ESC  |  TAB  | CTLR  |       | SHIFT | _RET_ |   "   |   ]   | Row 0
   |    |       |       |       |       |       |  ENT  |   '   |   [   |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A1 |  8 | __1__ | __2__ | __3__ | __4__ | __5__ | __6__ | __7__ | __8__ | Row 1
   |    |   1   |   2   |   3   |   4   |   5   |   6   |   7   |   8   |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A2 |  7 |SCROLL |SCROLL | __0__ | SPACE |   >   |   P   |   O   | __9__ | Row 5
   |    | UP    | LEFT  |   0   |       |   %   |       |       |   9   |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A3 |  6 |   Q   |   W   |   E   |   R   |   T   |   Y   |   U   |   I   | Row 2
   |    |       |       |       |       |       |       |       |       |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A4 |  4 |   A   |   S   |   D   |   F   |   G   |   H   |   J   |   K   | Row 3
   |    |       |       |       |       |       |       |       |       |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A5 |  2 |   Z   |   X   |   C   |   V   |   B   |   N   |   M   |   <   | Row 4
   |    |       |       |       |       |       |       |       |   ,   |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A6 |  5 |SCROLL |SCROLL |   _   |   ?   |   :   |   |   |   L   |   +   | Row 6
   |    | RIGHT | DOWN  |   -   |   /   |   ;   |   \   |       |   =   |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
A7 |  9 |       |       |       | ALPHA |       |       |       |       | Row 7
   |    |       |       |       | LOCK  |       |       |       |       |
---+    +-------+-------+-------+-------+-------+-------+-------+-------+
   |       10      11      12      13      14      15      16      17   |
   +----+-------+-------+-------+-------+-------+-------+-------+-------+
        |  D0   |  D1   |  D2   |  D3   |  D4   |  D5   |  D6   |  D7   |
        +-------+-------+-------+-------+-------+-------+-------+-------+
pins 1 and 20 are GND, pins 18,19 are not connected.

On the keyboard harness,Pin 1 is identified by a black stripe.

Update:
Charrisa posted a URL with the connector pinout so I'll add it below:
+---------------------------------------------------+
|  02   04   06   08   10   12   14   16   18   20  |
|  01   03   05   07   09   11   13   15   17   19  |
+----------------------|_____|----------------------+
The above indentation directly above corresponds with
the connector/cable orientation/polarity mark

 

[giobbi]

[as Asked by JDallas, I moved my message here from the other thread]

What I can say about my Osborne-1, is that it takes a long time before to load the operating system. It starts asking you a disk, you put a disk, hit the enter key and wait for more than a minute for the menu. Apparently it seems in a dead lock (i.e. bad disk, or drive issue): disk spinning but nothing more.

Ah, you can also make a boot disk using an old DOS PC with 5.25"-360 Kb floppy drive (I'm using my IBM XT for that) and the software "image disk". See: http://www.classiccmp.org/dunfield/img/index.htm for software and disk images .IMD - Set double step = off, 40 tracks, double side = on.

Note: I can only make working floppies from SSDD images.

You can also use .ID0 images using Teledisk software (Google it or ask me, I should have a copy, somewhere).

For some reasons, 1.2 Mb floppy disks don't work fine for that purpose. There's a tutorial about how to modify a 1.2 Mb drive for that:
http://www.classiccmp.org/dunfield/img54306/speed300.htm

I believe I tried but it didn't work for me; but I'm not sure, it was a long time ago (more than two weeks is "long time ago" for the RAM bank inside my poor, old brain ^_^ )

 

[Chuck(G)]

Moved per request:



(I think you mean .TD0 files)

It's best to use a 48tpi (360K) drive and DD media. HD has very different magnetic characteristics and doesn't work reliably. And your floppy controller should be capably of SD operation (use Imagedisk's TESTFDC program to see).

 

[giobbi]

Moved per request:

(I think you mean .TD0 files)

Oh, sorry, you're right. .TD0, of course.

It's best to use a 48tpi (360K) drive and DD media. HD has very different magnetic characteristics and doesn't work reliably. And your floppy controller should be capably of SD operation (use Imagedisk's TESTFDC program to see).[/QUOTE]

I'm using 360K drive but I can't say about media, today is hard to find reliable floppies. I bought 100 units but they're 1.2 Mb.
I will take a look with TESTFDC... it will took a while, since I have to get back my XT and my Orborne (they're stored in other place), but I will try and post the results here.

-- Giovi

 

[Charrisa]

My issue isn't really anything to do with the drives or drives' speed right now, it's get any input back at all, the BIOS seems to work fine as the "please put boot disk into drive A and press return" screen appears, but pressing any of the keys does not give any error message or any feedback at all.

 

[giobbi]

Osborne keyboard should be just a simple matter of passive matrix, different from the PC keyboards that come with some electronics inside.

Did you open the the keyboard and clean it? I've already seen (and fixed) many old keyboards with this kind of problem. In your case, it's enough the ENTER key contacts are dirty and you won't go ahead with the boot.

I didn't open the Osborne keyboard yet, so I can't tell you what to expect (springs, contacts, rubbers, etc.). But, at least, if you open it, you could fire up the computer and shortcut the ENTER contacts with a wire or a screwdriver, of course with a GOOD boot floppy into the drive. Then wait for at least a minute to see if it will boot.
This should at least answer to the main question: "is the keyboard bad, or is there any other problem?"

 

[JDallas]

If you need to test for an ENTER key, you could disconnect the keyboard and touch a wire between pin 3 and 15 of the system-side connector. If the electronics on the main Osborne board are properly scanning the keyboard, pin 3 will be cyclically pulled low and pin 15 will be sensed as having a low signal caused by the phantom ENTER key being pressed.

And if you see the Osborne respond to this key, its a fair indicator that a keyboard problem is part of the boot problem. If you can't get a reaction from the Osborne screen, its either not a key that it responds to, or the wire connection wasn't good enough to catch a polling of that row, or the keyboard scanner has problems (maybe instead of the keyboard, maybe in addition to the keyboard).

Now if you got a mating 20 pin connector it would be easier to touch the right pins. In fact you could wire it with just enough 'wire switches' to simulate the keys you needed to force the Osborne to boot off drive B.

To hook up the other key that makes it boot off of drive B: instead, just look at the keyboard matrix/table I posted and find the P1 connector pin for that key's row and column. I don't recall the key for sure, but I'll use double quote as an example: Row 0 connects to pin 3, Column 6 connects to pin 16. Bridging those two connector pins on the Osborne side of the disconnected keyboard should create a phantom double quote keystoke.

I wrote a Osborne-1 Keyboard Theory of Operation the other day, but it needed a little work. I might rework and post it.

Also, if Drive B is good and Drive A is bad... usually with some mechanical labor you could swap them. That's a lot more work and as it involves working around a voltage-charged CRT even when power is removed, I wouldn't recommend that as a first task for a newbie. The simple keyboard tests we discussed in IRC and the one above are a lot safer and quicker than swapping drives.

I'll check the schematics on the Osborne modified MPI floppy drives to make sure there are no issues. Anytime a company puts power voltages on a floppy cable where the standard drives have GROUND, a little caution is needed.

 

[Charrisa]

Did you open the the keyboard and clean it? I've already seen (and fixed) many old keyboards with this kind of problem. In your case, it's enough the ENTER key contacts are dirty and you won't go ahead with the boot.

I tried this, only to be greeted with full plastic casings that are melted into place. No getting to the contacts without breaking some plastic.

Sorry for the lack of updates, just started a new job and it's taking ALL my time, I will probably try something thursday night or following friday.

 

[Charrisa]

I unplugged the keyboard to test it, to learn that the pins on the keyboard's end of the plug are female, and the holes are small, so testing the keyboard will be very time consuming. I also tried to press return on the computer while it was running by using a wire to connect the pins that make up enter. I got some screen flicker, but not much more, then after a bit it made a ton of sound and then I smelled burning so I shut off the computer as fast as I could.

 

[giobbi]

I unplugged the keyboard to test it, to learn that the pins on the keyboard's end of the plug are female, and the holes are small, so testing the keyboard will be very time consuming. I also tried to press return on the computer while it was running by using a wire to connect the pins that make up enter. I got some screen flicker, but not much more, then after a bit it made a ton of sound and then I smelled burning so I shut off the computer as fast as I could.

I didn't open an Osborne keyboard yet, but -according to Jay's (Jdallas) explanation, it's just a matrix scheme; so, if you're absolutely sure you shortcut the right wires, I don't think it can be the cause of a fire problem (I think there's no way to damage the computer simply shortcutting the keyboard matrix wires, even if you choose the wrong pin... but I didn't test it for myself so I can't be sure of that).

Maybe it's the time to open the computer, at least to see what's up inside, if you're confortable doing that.
You must to remove the pot knobs, remove the frontal cover and the whole computer will slide over the plastic case... more or less. I don't remember exactly how many screws you should to remove, but to open an Osborne it's easy, you only must to remember about to remove the knobs first.

Try to see if you can detect what component is burnt, if any... but beware, don't touch the high voltage part (the board connected to the CRT, plus the CRT itself and its cable... to be bitten by a CRT it's not a funny experience, I was almost a child and I still remember ^_^ )

 

[JDallas]

...I don't think it can be the cause of a fire problem...

No power pins pins go to the keyboard. The only source of voltage its the pullup resistor on the main board side. The rows are scanned but pulling an open collector output low, any switch that is pressed at the time that's scanned, will have its other switch pin pulled low and that would pull a column pin low. Of course on the keyboard side, they previous owner suspected a stuck key, so disconnecting the keyboard immediately stops stuck key complications. Now the bridging wire between the correct row and column associated connector pins, is electrically identical to a key being pressed.

If you tied all 20 pins of the connector together in a really bad soldering mistake, hehe, all you'd do to the main board is consume a little current through all 8 of its pull-up resistors. Those resistors values are high enough to avoid wasting power or heating resistors, so yeah, really can't do anything bad. There is no power signal that can be shorted to ground.

...Maybe it's the time to open the computer, at least to see what's up inside, if you're confortable doing that...

Somewhere there is a Website where the took a Osborne-1 completely apart photographing every piece... I'll see if I can find that tomorrow, perhaps someone else knows where it is?

It would be a good idea to look at that website before going it... less surprises, more comfort in knowing what's what.

...Sorry for the lack of updates, just started a new job and...

Don't worry about that. A lot of people here only have time to pull out the vintage gear on some of their weekends. Do what's important for your job, and when you get time for the Osborne-1, we'll see your posting here.

...I also tried to press return on the computer while it was running by using a wire to connect the pins that make up enter. I got some screen flicker, but not much more, then after a bit it made a ton of sound and then I smelled burning so I shut off the computer as fast as I could.

Did it sound like the noise was in the floppy drives or in the video screen? The ENTER key is supposed to tell it to boot off of drive A which you said wasn't working.

When you touch the wire to simulate a keystroke, you need only hold it long enough to see that the screen does... does it print a letter? does it print a error message? does it scroll? Any response means it detected that key. The next step is to try to bridge a row and column combination that will actually print a useful keystroke indicator on the display.

Technically the endless scrolling shouldn't hurt the video display. Whatever you smelled would more likely be the result of the system endlessly trying to select the bad drive. The previous owner just said it was bad, we don't know how it is bad. Might need to remove the power plug from floppy drive A: if any hot smell persists.

The screen flicker may have been do to the initialization of the floppy failing and the system deciding with nothing else to do, it resets itself to boot up again, over and over. If you're doing something that gives the video display a headache, its best to stop.

 

[giobbi]

When you touch the wire to simulate a keystroke, you need only hold it long enough to see that the screen does... does it print a letter? does it print a error message? does it scroll? Any response means it detected that key. The next step is to try to bridge a row and column combination that will actually print a useful keystroke indicator on the display..

I'm almost sure nothing apparently happens when you hit a stroke... the drive starts to spin only. I have to verify that... maybe later, in the evening, I will have a little time to take the Osborne again, fire it up and make a clip to show you... But I'm quite sure no chars appears on the screen after you pressed enter.

Maybe the problem is related to the floppy drive... some components on the fdd board, after many years sleeping, suddenly went wrong. Maybe a caps issue?

 

[giobbi]

ok, I did a try on my Osborne. When you fire it up, it appears the "insert a disk in drive A and press RETURN" message. Floppy drives are both idle at this point. So you put a floppy in drive A, press return, and the drive A led goes on. Then you wait for a minute (in my case) and something will happen, depending on the disk content. It could be a menu, a simple A> prompt or everything else.

this is whay you should expect at boot.

Now, since these last weeks I win the "break your vintage computer" contest (*), I had to open the Osborne-1 because three caps on the power source decided to explode (I suspect one of them exploded today, the two others are cracked but not really exploded (yet)... I'm ran out of stock, so I have to go to the local shop and buy some). So I can exactly tell you how to open it.


BEWARE: *** DO NOT TOUCH THE HIGH VOLTAGE PART IN THE CRT SECTION: HUNDREDS OF VOLTS THERE, STORED IN THE CAPACITORS, THAT'S WAITING FOR YOU!!! ***

- remove the 6 screws on the frontal (black) panel
- remove the two knobs (brightness and contrast)
- remove the black panel
- remove the 4 screws from the lower side of the case
- open the case, removing the lower half shell.
- remove the fan and the power plug plastic inserts. No need to unplug anything for now. You can do it later, when you can see better where every wire is connected to.
- take the whole computer from the half shell. You can do that simply pulling out the whole block by the metallic frame.

- to access the floppy drive, you need to remove the mainboard: 4 screws. Beware not to broke anything doing that.




(*) It seems these days every vintage computer I fire up, burns... In june and july I had to fix a Commodore PET 2001/N, a Commodore 8032, a Zenith Supersport, a Macintosh SE (that's waiting for the RAM sticks), and now the Osborne... everything I touch, breaks (Not to mention a PC ATX power source I powered with 220v instead 110v ... damn'd double voltage brazilian system, I lived in Italy for almost 40 years where there's only 220v line, so sometimes I forget to check the voltage... well, just 2 big caps and a lot of smoke and smell...)

 

[Charrisa]

Did it sound like the noise was in the floppy drives or in the video screen? The ENTER key is supposed to tell it to boot off of drive A which you said wasn't working.

When you touch the wire to simulate a keystroke, you need only hold it long enough to see that the screen does... does it print a letter? does it print a error message? does it scroll? Any response means it detected that key. The next step is to try to bridge a row and column combination that will actually print a useful keystroke indicator on the display.

I heard what I assumed was a very fast fan, it retrospect it could have been the A:> drive trying to boot. When I connected the pins for the return key the screen flickered like mad, but that's it.

Also the burning "plastic" smell might have been me just freaking out while smelling the burnt dust.

 

[giobbi]

Also the burning "plastic" smell might have been me just freaking out while smelling the burnt dust.

You should see if it's not a capacitor on the power board; it's quite probable it is. In this case, good news: easy to fix, just replace them. Usually they don't affect other components, expecially if you unplugged immediately the machine from the AC line... at least in my (poor) experience.
You have to open it and see if there aren't broken caps; the possible culprit are the brick shaped ones (one 0.1 uF and two 0.01 uF). They're old and they explode, literally. And smell.
Other caps on the power board are the electrolytic caps, the cylindrical ones. When they're bad, they often pop on the upper side and/or leak electrolytic liquid. No way, must to replace too.