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geekhack Community => Keyboards => Topic started by: Shadow Lord on Mon, 30 April 2018, 19:26:13
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Hello Everyone,
Long time lurker - new poster.
I am owner of a very clean IBM 1397000 Model M 122Key Terminal Keyboard that I am trying to use with a Soarer Convertor. Unfortunately, this KB has a number of issues. The first was a bad flexy wire to the LED light PCB. I managed to hack my own cable for that and have the lights working. The second more serious problem is the bottom row of function keys (F1 - F12).
In that row only F1, F4, F7, and F10 work (yep every third key). All other keys on the KB work fine. The keys mechanically feel fine but they do not produce any scan codes (according to HID_Listen). I have resat the keys and resat the flexy cable with no change in behavior. I found another thread https://geekhack.org/index.php?topic=16190.msg323544#msg323544 (https://geekhack.org/index.php?topic=16190.msg323544#msg323544) that makes a reference to a thread with info on the membrane contact sheet. Unfortunately, the post it references seems to be gone. If anyone has the info on membrane sheet, trouble shooting, or fixes I am all ears!
Is this KB salvageable (not just for parts I mean ;)). Or is it pretty much a done deal? TIA!
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The usual...a broken trace. Take a closer look, it's likely near where the membrane "turns into" the plug-in ribbon.
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The usual...a broken trace. Take a closer look, it's likely near where the membrane "turns into" the plug-in ribbon.
I figured as much but I was hoping to be able to better localize it. Also, the pattern is a bit weird - after all if one trace was broken would it create a pattern of broken keys every third one? And if more then one trace gone wouldn't you expect more keys not to work?
M<ore importantly can the trace be corrected? Or does it need to be replaced?
TIA!
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It's been a while since I've looked at a 122 membrane, but I'm fairly certain the F keys have at least one dedicated trace and it follows that kind of a pattern (2 keys, skip, 2 keys..). It's easily fixable if it's outside of the assembly, either via conductive tape or glue or a combination.
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It's been a while since I've looked at a 122 membrane, but I'm fairly certain the F keys have at least one dedicated trace and it follows that kind of a pattern (2 keys, skip, 2 keys..). It's easily fixable if it's outside of the assembly, either via conductive tape or glue or a combination.
Does anyone have the PDF that shows the membrane layout for the 122 keys? Unfortunately, the thread it was in seems to be gone (unless I am doing something wrong). The controller PCB has three flex connectors.
1. wide one which seems to be for the main KB
2. a smaller one that controls the function keys (disconnecting this keeps any of the function keys from working)
3. and one to the LED PCB
The one going to the function keys has six wires on it and I think I see a break in one of the lines but I am not sure if that is it or not. Where can I get conductive tape to test it out (any particular brand) or is there an easy way to test it beforehand? Thanks.
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Use a multimeter to do continuity test, just pick the cheapest one with continuity function?
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Does anyone have the PDF that shows the membrane layout for the 122 keys? Unfortunately, the thread it was in seems to be gone (unless I am doing something wrong). The controller PCB has three flex connectors.
1. wide one which seems to be for the main KB
2. a smaller one that controls the function keys (disconnecting this keeps any of the function keys from working)
3. and one to the LED PCB
The one going to the function keys has six wires on it and I think I see a break in one of the lines but I am not sure if that is it or not. Where can I get conductive tape to test it out (any particular brand) or is there an easy way to test it beforehand? Thanks.
That's not how they work.
The wide one is for the keyboard columns. Narrow one is for rows. (Generally speaking, the F keys on the 122 kinda screw with this, but that's the idea).
Apart from a continuity test, an easy way to test is to get a strand of wire and bridge where you think the break is, and try the keys. Near the connector the membrane has a coating so make sure you're testing where you can actually contact the trace.
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So I got some conductive tape and tried repairing the cable. As I did not want to break the plastic rivets I focused on the PCB connector end of the cable. Unfortunately, there is no change in behavior. Those 8 keys out of 122 still are not working.
I then tried repairing the LED cable since that was easily accessible:
(http://[attach=1])
On the repaired wire I am still unable to get continuity. So if something is going on it seems to be in the middle of the wire (under the mylar sheets) or I am missing something simple but significant. Any help/pointers/ideas? TIA!
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Maybe get a new membrane from Unicomp?
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Maybe get a new membrane from Unicomp?
Yeah too much work, hassle, and expense for the KB.
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Maybe get a new membrane from Unicomp?
Yeah too much work, hassle, and expense for the KB.
Unless you have it professionally fixed.
https://imgur.com/a/tIonH
That might be a consideration.