apple II keyboard messed up

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apple II keyboard messed up

hi everyone, i recently unsoldered the key of my apple II but when put back on, the assignment of each key is different for example the space bar will type "@" or the keys "qwe" won't register at all. when i did the job the solder i used was obviously too hot, i just learned the hard way you cant use any soldering iron. 

 

sill i cleaned up all connection and i am positive no connections are overlapping or touching each other

 

i am truthfully lost here and have no idea what to do. anybody has a clue on how i could fix this or least how to find where the problem comes from?

 

thanks in advance

 

 

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Some questions

Hi. The pictures show almost all keys are removed from the keyboard. Is this a current picture or are all the keys soldered back on? I had a similar problem with my keyboard. Can you make a mapping for each key (key pressed and what character is shown on the screen)?

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thanks for the reply.

thanks for the reply.

 

after i cleaned the board with alcohool i soldered them back and then the mapping was messed up. 

i did not map it all at the time but it was very similar for example the space bar would produce "q@" 

so i desoldered everyting again because i thought at the time the solder might have touched each other or something. but even without the keys, like if i use my finger to make the connection if would still produce the same messed up input.

all the inputs are now consistant almost as if it was reprogrammed.

here is the map, i tested with both my fingers and a key.

the reset key works well and i also have different connection cables  which all produced the same results

1  = q

2 = r

3 = s

4 = t

5 = u

6 = v

7 = w

8 = p

9 = q

0 = nothing

: = r

- = e

esc = s

q = nothing

w = nothing

e = nothing

r = nothing

t = t

y = q

u = nothing

i = nothing

o = g

p = p

repeat = nothing

return  = e

ctrl =nothing

a = a

s = s

d = d

f = f

g = g

h = @

j = b

k = c

l = d

; = s

left arrow = @

right arrow = u

shift = nothing

z = r

x = p

c = c

v = v

b = b

n = f

m = e

, = d

. = f

/ = g

shift = nothing

spacebar = @

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all i can think of is that my

all i can think of is that my solder was too hot and maybe messed up the chips on the board. what do you think? i learned how to solder, my hobby is to fix electronic (sometimes old) for free. but i never had anything that old and sensitive, (and i fixed stuff like the first walkman) the board was really displeased with the heat.

 

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Most probably an encoder

Most probably an encoder issue... replace it.

 

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the endoder thanks

the endoder thanks

 

which chip is that? is it the one that can be removed by hand

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Encoder chip

 

The encoder chip MM5740AAD/N is very sensitive to ESD (electrostatic discharge). Hopefully that is not the problem... they are difficult to get and some of the ones on eBay are not the correct ones for Apple II's because the characters are mapped differently.

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is it this one (red square)?

is it this one (red square)?

 

if so then it cant be, i have a second apple 2 which keyboard does not respond at all.

 

i swaped that chip and it produced the exact same result

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Aye, that's it. I can still

I believe that the encoder on mine is likewise dead due to various work restoring it (soaking in DeOxit); however, given that everything is just offset, I would look for any lifted pads or traces. If you spot any, bodge them and see if it helps. Be sure to bodge along the entire path of a liften pad or trace, both sides of it, and anything branching to/from it. 

 

Right now, mine has gone from being partly unresponsive, to only registering '2' if I press half of the keys at one time, which either means that my encoded is dead, or that the deoxit in the switches is preventing them from making contact at all. 

 

You have a model 2 Datanetics board, with DC-50 series switches. Even if you were to get it working electronically, there is no reliable way to repair the keyswitches. Where did you source replacements, and at what price per switch?

 

I should be receiving some encoders soo, so if you end up needing one, let me know. 

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sure, how much for an encoder

sure, how much for an encoder?

 

regarding the pads, some pads came off but only those that stand on their own without connections. I carrefully checked, and cleaned, all connections are fine, but even if i was wrong about that, some keys loaction that lost a single pad are still responding while others that stood the heat perfectly and are still there perfect and shiny do not respond.

 

i really dont think it comes from the pads but i also swapped the encoder already and got exactly the same result.

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My bad encoder and dirty key switches gave similar results

I compared my "key press to character on screen" results to yours and they have some similarities (for some reason I cannot attach my screen-shot results). I found that to resolve my keyboard issues I had to clean some of the key switches with contact cleaner after removing keycap. To get the number keys to work I had to swap the keyboard encoder from my working keyboard from my other Apple II. I had ordered two encoders on eBay and was considered "lucky" to get one that actually worked. I put that one in my other Apple II. I bought my encoders from this seller:

 

https://www.ebay.com/itm/1PCS-MM5740AAE-N-Encapsulation-DIP/382182303990?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

 

I see that there are some sellers of this encoder in the U.S. now. I guess if I needed another encoder I would order 2 from my prior source and hope that one worked.

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Apologies if I've missed some

Apologies if I've missed some details, but I experienced some very strange behaviour from my own Apple II keyboard after cleaning some key-switches internally with isopropyl alcohol (to relieve contact problems). Turns out that the alcohol hadn't dried up completely and was causing (partly) electrical contact inside. I let it dry in a warm environment for a few days and the problem was gone! Read more here. Maybe something similar is going on with your keyboard.

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jrme421 wrote:sure, how much
jrme421 wrote:

sure, how much for an encoder?

 

regarding the pads, some pads came off but only those that stand on their own without connections. I carrefully checked, and cleaned, all connections are fine, but even if i was wrong about that, some keys loaction that lost a single pad are still responding while others that stood the heat perfectly and are still there perfect and shiny do not respond.

 

i really dont think it comes from the pads but i also swapped the encoder already and got exactly the same result.

 

I will likely have them in one to three weeks: I'm unsure as to from what country they are being posted out.

 

I would *prefer* to test them prior to selling them, or quoting a price, but I will inform you in any case when they arrive, should you still need them.  Ideally, I'd like to see you get this mechanism working w/o swapping the encoder, and as you tried that with the same result, I suspect that you lifted a pad or damaged a trace, so the signals going to the encoder are incorrect. 

 

If you want to send the assembly for inspection and service, I *may* be open to that, but you should use a probe to check continuity between each pad and the locations to which it connects (follow the traces). If any of those traces fail continuity, add a bodge. 

 

I'm still curious where you found switches for it, as I would like to obtain a stock of DC-50 series switches for my own machines. 

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old_hitech wrote:I compared
old_hitech wrote:

I compared my "key press to character on screen" results to yours and they have some similarities (for some reason I cannot attach my screen-shot results). I found that to resolve my keyboard issues I had to clean some of the key switches with contact cleaner after removing keycap. To get the number keys to work I had to swap the keyboard encoder from my working keyboard from my other Apple II. I had ordered two encoders on eBay and was considered "lucky" to get one that actually worked. I put that one in my other Apple II. I bought my encoders from this seller:

 

https://www.ebay.com/itm/1PCS-MM5740AAE-N-Encapsulation-DIP/382182303990?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

 

I see that there are some sellers of this encoder in the U.S. now. I guess if I needed another encoder I would order 2 from my prior source and hope that one worked.

 

Do you know of a good test procedure to test them without plugging them onto a PCB? I should look up the datasheet, but if they can be tested with +5VCD and earth, with a scope, that would be ideal. 

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I do not know of a test other than the data sheet

I do knot know a good test procedure. It would take some effort to construct a test setup for the encoder. I think the best test is to just install the new encoder onto the keyboard and connect keyboard to the computer and see what you get on the screen when you press a key. You do have to have faith that your keys are operating correctly. 

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welll i dont think people

welll i dont think people noticed what i said here but i already have another encoder (from amother apple 2 which keyboard does not respond at all) and the results are exactly the same regardless of the encoder i use

 

so it must come from somewhere else.

 

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thanks for your help

thanks for your help

i put some all purpouse oil (4drops per key) in all keys cause they were sriously stiff. it solved the problem.

i dont know if it really causes the issue there cause i use a voltmeter to test every one of them and the current goes trhough only if i press them, 

 

also i tested the reaction of each location on the board whithout the keys, by pressing my finger on each side and it would input the same result. 

 

now i have put back the keys without solder and the results are more messed up than before, i havent soldered anything yet just put the crews on, and the one key that was  and still is soldered stopped inputting, the sapce key.

could it beshorts? but i looked very closely and cleaned carefully all connections, at this point if thats the issue how can i fix this?

 

 

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also another therory, the all

also another therory, the all purpose oil i used to unstiff the keys is creathing shorts all over the board, is oil conductiove?  i thought not thats why i used it and very little at that

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jrme421 wrote:also another
jrme421 wrote:

also another therory, the all purpose oil i used to unstiff the keys is creathing shorts all over the board, is oil conductiove?  i thought not thats why i used it and very little at that

 

Well, you probably forever ruined those keyswitches. The DC-50 uses a mylar and brass sandwich mechanism to conduct, and now you have poured a nonconductive mateiral in there. Pull the ICs, soak the entire thing, immersed in 99% alcohol (must be pure), for a few DAYS n a cool encironment, to dissolve that shyte. 

 

If you are lucky, you won't have dissolved the internals of the switches. Never, ever, use a product like that on an electrical component. 

 

In general, you need to be patient with this stuff. It can at times take weeks, or months, to properly restore a mechanism like this; as spares basically are unobtainium. 

 

I used an 'appropriate' chemical, DeOxit (normal, and wiper), and I believe that destroyed my own keyswitches, but we'll see. At worst, I can put in the Datanetics Model 3 version, and live with that. 

 

Your actual issue before was probably a lifted trace. I said that several times. If the signals going to the encoder matrix are being interrupted, it will produce the wrong result. You can experience the same issue if you have desoldered vias that need to be connected.

 

 

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It occurs to me now to ask:

It occurs to me now to ask: Did you test the KB on more than one Apple II mainboard? It could just be losing one bit due to a mainboard issue. 

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i guess i wont use it anymore

i guess i wont use it anymore but the switches are still responding fine. i tested everyone of them to and it goes through

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no i havent tested, but i don

no i havent tested, but i don't think so, i disconected the keyboard everytime i worked on it

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jrme421 wrote:no i havent
jrme421 wrote:

no i havent tested, but i don't think so, i disconected the keyboard everytime i worked on it

 

Please try it on another ][ or ][+, and post the results. Use a ][+ is possible as ][+ mainboards are more comon and if damaged, not as difficult to replace. 

 

I managed to rescue mine a bit, but some of my switches still do not work after exhaustive restoration. I will need to replace at least 6, if not 10 switches, on it, so if you have a source for them, i would appreciate knowing it. Most of my keys now work and no longer stick. I need to verify that the non-working keys aren't on the same signal path from the encoder. If not, then this also gives me a valid way to test encoders, which means that I can certify encoders as non-defective.

 

(I am not comfortable selling encoders in 'as-is' condition.) 

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jrme421 wrote:thanks for the
jrme421 wrote:

thanks for the reply.

 

after i cleaned the board with alcohool i soldered them back and then the mapping was messed up. 

i did not map it all at the time but it was very similar for example the space bar would produce "q@" 

so i desoldered everyting again because i thought at the time the solder might have touched each other or something. but even without

 

Something else to consider, is that this may be a fault on your mainboard. Have you tested another Datanetics KB on the same  mainboard?

 

If not, possible causes include:

 

Bad 2513 ROM
Bad 74166  at  A3
Bad 74LS257  at  B6
Bad 74LS257  at  B7
Bad 74LS174 at  B5  
Bad 74LS174  at  B8
 

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