IBM model F XT not working suddenly

[Darkshado]

Take pictures from several angles, the description alone makes it difficult to understand what the problem could be.

[kmnov2017]

From what I understood from your post - your keyboard is unresponsive even after switching two different soarer's converters. The keyboard did work before you mention.

So first of all stop disassembling the keyboard and putting it back on. That's not the problem. You only risk destroying the flippers if you aren't careful. From what I gather, you've already destroyed three.

Your problem is either with the Soarers converter on the native controller on the board itself. The soarers converter can be tested with any other keyboard. Any keyboard with a large DIN connector may be used to test the soarers converter. If this test keyboard works, the soarers converter is fine. If I understood you right, you mention that the soarers converter is being recognized in device manager - in that case its almost definitely not the problem.

If there's a problem with the original controller, identifying the part that's defective is going to take some work. If you don't have a background in electronics (I am assuming you dont, otherwise you'd have just made your own soarers converter), this is going to be a challenge. It could be a capacaitor that's gone bad. You can't test this with a multimeter either. The capacitors will have to be removed from the board in order to test them.

Replacement controllers are difficult to find, though there maybe some one who's selling on DT, ask around. The only other cheaper option is to replace the controller with a cypress CY8CKIT-059 (Costs about 20 euros in Europe). But this requires quite a bit of soldering, programming and patience. The other option is an Xwhatsit controller - but I haven't seen these being sold in a while and they are expensive.

I see that you've already spent a princely sum for an XT plus two soarers converters. Weigh your options on how you want to proceed.

[Kashtan]

From what I understood from your post - your keyboard is unresponsive even after switching two different soarer's converters. The keyboard did work before you mention.

So first of all stop disassembling the keyboard and putting it back on. That's not the problem. You only risk destroying the flippers if you aren't careful. From what I gather, you've already destroyed three.

Your problem is either with the Soarers converter on the native controller on the board itself. The soarers converter can be tested with any other keyboard. Any keyboard with a large DIN connector may be used to test the soarers converter. If this test keyboard works, the soarers converter is fine. If I understood you right, you mention that the soarers converter is being recognized in device manager - in that case its almost definitely not the problem.

If there's a problem with the original controller, identifying the part that's defective is going to take some work. If you don't have a background in electronics (I am assuming you dont, otherwise you'd have just made your own soarers converter), this is going to be a challenge. It could be a capacaitor that's gone bad. You can't test this with a multimeter either. The capacitors will have to be removed from the board in order to test them.

Replacement controllers are difficult to find, though there maybe some one who's selling on DT, ask around. The only other cheaper option is to replace the controller with a cypress CY8CKIT-059 (Costs about 20 euros in Europe). But this requires quite a bit of soldering, programming and patience. The other option is an Xwhatsit controller - but I haven't seen these being sold in a while and they are expensive.

I see that you've already spent a princely sum for an XT plus two soarers converters. Weigh your options on how you want to proceed.

Thank you very much for extended answer.
My first converter, from the Philippines, which I returned, according to the seller, was also a worker.
He typed my answer from the keyboard connected to my converter, according to him.
My current converter, from another seller, from the USA, is determined by a computer.
Moreover, the third converter is also coming to me!
But something tells me that this is not a converter.
Yes, I searched, there are no controllers.
And quite rightly, it cost me too much, and a lot of nerves.
I have not had such an unsuccessful purchase.
Not a single master takes care of repairs.
I guess I'll look for a controller, or create a topic about buying it.
If I don’t buy, I won’t be surprised anymore -
I will buy Chinese consumer goods, with silver low profile cherry.

Thanks to everyone who tried to help.

[Kashtan]

Yesterday i trying another (third) Soarers converter.
Nothing.
Just of junk.

[Fkazim]

Hello to all.
Today i receive converter from another seller from ebay, from states.
Drivers installeds, but keyboard not working. Any buttons.
Also two thoughts:
when puch buttons, strange ringing, as if something is not attached inside, (as empty bucket) on any video did I no hear a ringing with this keyboard. This normal?
The second - I remembered that during disassembly, three switches were broken, could they close the board and it blocked?
Reason again make out XT, and get out this three switches. Without them, and try again to launch. Or purchase 3 switches capacitive buckling springs from ebay?
So, Is there any reason to carry it tomorrow for repairs? Tomorrow I’m going to bring my new CPU to the binning procedure, at the same time I can bring the master and keyboard ...
I would be grateful for any thoughts!

When you say "ringing sound" do you mean a sort of ping sound on every key or is the sound only heard on certain keys? Also double check the continuity of all the DIN's cables wires beyond that I would say it is something that has gone on the original PCB.

[Kashtan]

[/quote]


When you say "ringing sound" do you mean a sort of ping sound on every key or is the sound only heard on certain keys? Also double check the continuity of all the DIN's cables wires beyond that I would say it is something that has gone on the original PCB.
[/quote]
This sound on any button. I check many all cables.

[solkoseryl]

Hello guys,
I've got the same issue.
All of a sudden, my F XT refused to work. (Soarer's converter on a Pro Micro clone.) Right before the failure it started to type itself some garbage, I've plugged the USB off, and then on again. And enjoyed the silence.
I've flashed another Pro Micro and tried it, but with the same result. Nothing.
Here is the output of hid_listen:

Code: Select all

Waiting for new device:...
Listening:
wEE

remaining: FFFC

Keyboard ID: 0000
Code Set: 1
Mode: PC/XT

And that's it. Doesn't matter what I try to type, no single keypress is registering.
I've unscrewed the back lid and tested the cable with multimeter. It's totally alive, continuity is rock solid from Pro Micro outputs to corresponding contacts on the keyboard PCB (right through the plug, too). The screw which presses PCB to the plate is tight.
My F XT turns out to be of revision 2 (without "Reset").
I reckon the controller is dead. Am I right?
Does anyone have the schematics?

Thank you in advance for the answers!

[SneakyRobb]

HI, I think the keyboard stuff is on page 76-90

http://bitsavers.trailing-edge.com/pdf/ ... _Apr84.pdf

[solkoseryl]

Thank you very much.
So, the biggest chip is Intel 8048 controller. Is it flashable? Or if it's a culprit, and I change it, will it work right away?

[SneakyRobb]

Thank you very much.
So, the biggest chip is Intel 8048 controller. Is it flashable? Or if it's a culprit, and I change it, it will work right away?

Hi, I do not know whether that will work or not. I suppose it is possible, but I have no experience.

I am not saying its impossible for the chips to fail, but if they failed I would think you wouldn't have intermittent typing if that were the case.

With Model F, the best recommendation is almost always try to disassemble the keyboard and then to reassemble it. In my experience as well as reading other people such as Fohat, this is almost always the thing you should try before any more drastic measures like replacing Chips.

[solkoseryl]

Hey
No intermittent typing whatsoever. It just died completely.
What do you mean by disassembling? To part the plate from PCB, put off keycaps and pull all flippers out? How come it could be of any help?
I already put off the back lid, unplugged the internal cable connector, and plugged it back in. Both the connection and the cable are OK.

[SneakyRobb]

Hey
No intermittent typing whatsoever. It just died completely.
What do you mean by disassembling? To part the plate from PCB, put off keycaps and pull all flippers out? How come it could be of any help?
I already put off the back lid, unplugged the internal cable connector, and plugged it back in. Both the connection and the cable are OK.

Hi, Ah kay then about completely dead. That is most unfortunate.

In general most model F issues are resolved by taking the keyboard module out of the cause, sliding the steel plates apart and then reassembling it. Usually it helps, but I suppose not in this case.

For your issue of complete electrical death I do not know then. Hopefully another member has more insight.

[solkoseryl]

It turned out that Intel 8048 is a factory flashed chip. Good news: there is Intel 8748, the same chip, but rewritable. Also, as far as I've found, there is no write protection exists in this chip family.
So, the plan is:
To desolder and check the capacitors.
To find the firmware of 8048 dumped by someone(?).
To buy 8748 (they are available). Maybe, for me it will be even easier to get KM1816BE48, which is 1:1 Russian clone.
To flash it.
I think, it will be sufficient for reviving my beloved F XT.

[inmbolmie]

It turned out that Intel 8048 is a factory flashed chip. Good news: there is Intel 8748, the same chip, but rewritable. Also, as far as I've found, there is no write protection exists in this chip family.
So, the plan is:
To desolder and check the capacitors.
To find the firmware of 8048 dumped by someone(?).
To buy 8748 (they are available). Maybe, for me it will be even easier to get KM1816BE48, which is 1:1 Russian clone.
To flash it.
I think, it will be sufficient for reviving my beloved F XT.

Google for "kb_pcxt83.zip" and you will easily find what (I think) is the right firmware for an IBM 1501105 F XT.

For the programming you will need a special programmer as those chips aren't "flash", as flash memory didn't exist at that time. They are PROM or UV-EPROM (8748H), the latter being better as they are erasable (with a proper uv-eraser) in case something goes wrong with the programming. You will need something like an improved Willem programmer with a MCS-48 adapter.

[solkoseryl]

Thank you very much for suggestions!
I have already found a guy who dumped the ROM seven years ago. He just sent me the binary. It turns out that there is absolutely no difference between two
Also, I've found a store in Moscow which does not just sale chips, but also have a service of programming them by request. Actually, there are several of such stores, but only these guys agree to work with KM1816BE48 / 8748H. Yes, I used the wrong term. They said it requires UV erasing and then using a rare ancient programmer which they happen to have. I think it's much cheaper than buying such equipment myself, especially for one-time task.

[orihalcon]

If it was me, I'd probably just get a different capsense PCB or I suppose a desoldered chip from someone who's parted their XT out if you're 100% sure that's the problem. Other thing you can do is cut the original controller part off and replace with an Xwhatsit as I have done here: viewtopic.php?t=19522

[solkoseryl]

Thank you, orihalcon! It's just ingenius! I've never ever dreamed of such a simple solution
I'll try my plan first just because it's much cheaper (and I've already ordered the programmed controller). But if it doesn't work, I'll definitely follow your recommendation!
I've got just one question. Where does this green and white wire goes? To the ground on the back side?

[Weezer]

If anyone's still having issues with this, and theyre sure its the controller board, can send someone an xt controller for the cost of shipping.

[JBert]

If anyone's still having issues with this, and theyre sure its the controller board, can send someone an xt controller for the cost of shipping.

It seems you forgot a few words there. I guess you mean that you have a spare controller which you are willing to send to someone if they pay for shipping?

[Weezer]

If anyone's still having issues with this, and theyre sure its the controller board, can send someone an xt controller for the cost of shipping.

It seems you forgot a few words there. I guess you mean that you have a spare controller which you are willing to send to someone if they pay for shipping?

Yep that is what I meant. And yes, I see I'm missing an "I" between "board" and "can". Thanks for pointing that out!