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At last my empty A2S1 case has a computer in it. The Rev 04 board I bought from ebay arrived. And actually, it worked right out of the gate -- came up to the usual Apple II screen right away.
There are a couple things:
- The keyboard sort of half works. Many of the keys produce the wrong characters when punched - ie. 1 produces a 0, A produces a @, etc. I don't know much about original A2S1 keyboards -- I'm assuming this is a problem with the keyboard itself? How much pain am I into to try and fix that? Reason I ask is I managed to wreck my Apple II+ keyboard.. which now doesn't consistently produce the right characters either. I found the metal tabs in the A2S2 to be way too sensitive and finely calibrated. And of course, the power light doesn't work.
- I notice the text is kind of 'multi-color'. This is how it should look for a Rev 04, right?
- The system will not boot if I put a Disk II card in there. In one of the slots, the drive whirs but the system won't even post. In the other slots, it pretty much ignores it, save for a brief flicker of the drive status LED.
One thing I was curious about.. I had been expecting the slots to be dark green... these appear to be black. Obviously this is a rev 04 board, I pulled the CPU and checked the part number underneath -- but I had thought black didn't appear until later?
Now I just have to score some integer ROMs and voila, we have an A2S1 assembled from parts.
Congrats! Any pictures? A power light can be had on ebay for cheep for these computers.
Like I said in your other thread; you have a late model REV 4 motherboard. It still uses the 16k ram jumper blocks, among a few other chips. But it does not use the dark green style slots.
Here is the lamp: http://www.ebay.com/itm/Apple-Keyboard-Lamp-/200878968988?pt=US_Vintage_Computers_Mainframes&hash=item2ec551d09c
Corey will have to confirm on whether a rev 4 should have multi color text or not. I personally have never seen multi colored text come out of my rev 4. Could the color killer be dead?
I've added some pics.
I accidentally broke one of the keys while getting the keycaps off.. split the body of it in two (looks like it's designed to do that. Not sure if I can get it back together.. the soldered half is still in place, but the little pieces of 'foil' and plastic are separated now and I'm not sure how to put them back. But in one of the pics I think you can see corrosion on the part still soldered to the motherboard.. I think that's what I'm battling with the keyboard. Not sure if I could do a vinegar/water bath maybe?
Most of the keys do not work properly.. wrong characters, etc. I've tried the alcohol + 40-50 up and downs but no change on the worst keys.
Oh.. and I got the power light to work.. just needed to be secured better.
I tried a lot of things to get my original keyboard to work, but was unsuccessful. I wanted to have a functioning keyboard so I used a keyboard from an early Apple II+. Works great! Hope you get your keyboard working. I may have a few keys from an original keyboard that are working. If you need some let me know.
-Gil
Yeah I am really not in love with Apple II keyboards. Oh well.. I'll have to try what i can. Have to figure out a way to deal with the corrosion.. if it can be done. We will see.
Just so I'm clear here, there were A2S1s with the later Rev 4 board like mine with the black slots? I'm assuming yes, since the last A2S1s used Rev 7.. but I wondered if black denoted use in the A2S2 or something.
Well just some remarks:
trying to boot from Disk will be quite difficult as far as the RAMchip in the last row ( position E3 )
is missing.
It´s indicating that the languagecard is missing and the missing chip had been relocated to the languagecard....
next point is fighting dirt on the board.....
there are several possibilities to remove the dirt...
some have done with dishwashingmachine ( some descriptions in internet and here in former threads.... )
BUT using this method requires plenty enough time to get the board dry after that procedure !
i prefer the method of using CO2 ( thats a method rather more rare and used more often for cleaning cars and motors )
and for less well results just using a brush should at least sweep off a good portion....
and the display of colors on letters in the desplay is rather more a question of adjusting the focus and channel on the
TV / Monitor,
and the keyswitches well.... maybe it might get you ahead to take some time reading my page about that topic
( 8th topic in the list of the apple II section ):
http://www.appleii-box.de/
in general it´s a fight against corroded metal and just as explained dozends of times here in various threads
pushing them several dozends of times ( varying from 50 to 160 pushes ) helps removing the oxydation....
for futher advance in your task it will be upmost important to top of your list to get the row with RAM
completed ( at position E3 ) which should enable you to boot from disk and use diagnostics disk for further testing....
speedyG
Thanks speedy.
I wondered about the missing RAM.. I had seen on other Apples that that position was usually where expansion cards plugged in.. since there wasnt one i figured that was how it was supposed to be. I have tons of Apple RAM.. the only thing that is throwing me is that that row and the row below it appear to have different RAM chip numbers?
Are there any good explanations of how exactly the kwyboard works? I am just not understanding what could cause the S key to spit out R instead.. etc
I pulled all the gold 4116s I had from my 'custom' motherboard that originally came with this case and filled all the RAM banks, including the one that was empty. The machine still comes up to a prompt ok, but no attempt at all to boot from Disk II.. no sound of it trying to operate, etc.
well in general it should be a 4116 RAM
the number afterwards indicate the speed...
examples:
4116-15 = 150 ns
4116-2 = 200 ns
4116-3 = 300 ns.
if possible take speed same as rest of the row...
there are 2 rules:
1. each row of chips ( consisting of 8 chips ) row c , or row d or row e shall be of same speed....
2. if rows have different speed ( i.e. 200ns and 150 ns the faster chips in lower row ( C or D )
and slower chips in higher row ( D or E )
related to the keyboard:
there are several possible causes for malfunction....
the causes i listed are just the most common ones....
i recommend to download the apple II circuit description from Winston D. Gaylor
that book has the circuitplans of the different versions of the apple II and a extended description to the functions within the book.... it´s availiable at asimov and it will surely be a recommended source for repairs...:
ftp://ftp.apple.asimov.net/pub/apple_II/documentation/hardware/machines/
the fifth book in the list - left click and choose download....
second recommendation is the last book inm the list:
understanding the apple II
it should be downloaded too....
speedyG
Since A is one bit (the low bit) off from @, and S is the same bit off from R, I'm guessing somewhere along the line the low data bit is being lost, either at the chip or at the cable. Cleaning may fix that.
Yes I've changed the cable, but now looking at the socket.. looks like a clean is needed.
Is there likely any harm to doing the 50/50 vinegar/water bath? I've done this with other boards and had great success. Don't have a dishwasher.
vinegar is not a good idea, due to the fast that it´s acid starts chemical processes....
clear water or clear water with few drops of dishcleaner ( they don´t contain acid but instead tensides )
or alternate using earcleaning tabs like Q-tips and isopropanl alcohol ( preferrably 90% less good 70% ).
speedyG
Yeah I've tried the q-tips/toothbrush with alcohol but it's changing nothing at all. Dishcleaner, you mean like dish soap (the kind you use with washing dishes by hand) or automatic dishwasher cleaner?
the normal one used for washing dishes by hand....
the purpose is that the tensides let the water creep below the dirt
and then dirt gets splashed away when cleaning with a brush and then sooner board is getting dry....
the problem with vinegar is that it starts reacting with metal and initiates a corroding of the metal...
at the beginning it looks pretty nice and clean but if you view the metal 2 or 3 weeks later
you will find out that corroding of metal starts worse than it had been before....
and if cleaning with isopropanol alcohol the better tool is an old toothbrush ( hard type )....
speedyG
I'm beginning to think my problem isn't the contacts. I have been doing continuity testing between the two poles of each switch, and have confirmed that on most, when the switch is pressed, continuity is OK. My Enter key is an example.. it establishes a proper contact (multimeter goes to 0) when pressed, but there is no reaction from the system.
I discovered that one of the pin sockets for the keyboard controller chip wasn't giving good continuity. After soldering in a patch (wire from socket around to where the pin sticks through on the other side, I got my space bar working.
I've tested continuity of most of the traces also and none have failed thus far, including the ones on where keys aren't working. What I haven't tested are the traces that run from the first pole of each switch (can't see where they go). I'm going to make it a mission tomorrow to single out one key, like the enter key, and follow the traces to all their endpoints.
it seems your battlefight is against aged solderlead. It´s fact that solderlead may loose its continuity.
In German language ( i assume by username that you are from there ) the term is "Bleifrass" ( lookup at Google )
- in english the term is leadtetroxid - if the board you have now, has been within the last 30 years a while in coastarea, the salt in the air causes that phenomenon. In such case it´s recommended to clean all solderingpoints with a soldersuckingpump sucking out the bad solder and resolder the board with new good soldering material to re-establish good solderjoints.
speedyG
Yeah I think that's a good part of it. I just wish I could more easily trace the traces on the top side of the keyboard to make sure they aren't broken. It's looking like I will need to desolder all of the keys and inspect those, then resolder? Ugh.
If anyone does have some spare keys they'd like to sell me.. I'd be all over it. I definitely will need at least two.
If you have unsoldered the damaged keyswitches and you have viewed my page that i listed above -
it contains description how you can repair and often might get that bad keyswitches working again !
In general it´s not needed to remove all keyswitches.....
when desoldered and resoldered nearly all of the keys should be working again !
In general broken traces are the most rare reason for malfunction !
speedyG
So you think simply 'reflowing' the old solder won't work -- I need to remove the old solder and put new in, pin by pin?
I don't see any evidence of damage to traces from what I *can* see.. I wish I knew if the controller chip was working properly though -- because I kind of wonder about that too.
Thanks for all your help thus far!!
If one solderjoint fails due to the bad connection - then it´s rather sure that major parts of the rest will fail soon too....
second: just adding some more new solder is like adding some minor part of new coke in a coke that´s 3 weeks old....
would you still want to drink that coke ???
speedyG
I've desoldered the entire top row of keys. (I added a pic of it above) Traces are in excellent shape.. no breaks. Going to do the rest tomorrow.. test all the traces. I'm testing each key too for continuity.. so far I have two bad ones for sure.
I'm trying to understand how a potential bad key somewhere could cause the wrong character to come up. The schematics don't make this clear to me (I'm not good at reading them though). If the traces are all good, and the switchs really are just simple switches that can't modify the output of another key on the same trace.. problem has to be with the controller chip(s)?
Did you download the books i recommended ?
speedyG
Yes I've been trying to read and understand them.
Getting there.
I've removed *all* keys now... same behavior if I short the key switch holes. I'm wondering if there's any chance my problem could also be with this Rev 04 board I have? I tried connecting a II+ keyboard (the one with the extra encoder board) but it won't boot with that connected.
I'm thinking the controller chip socket might be at issue, I know for sure one pin was bad.. and I can still see a bit of corrosion in there. So I'm going to replace that.
Wish I'd done this before -- I borrowed the keyboard from my Linden Series One, which is basically a direct clone of a Rev 04 Apple II (even the prototyping area is the same). Plugged it into the Rev 04 board.. and surprise! Exact same keys with the exact same issues. So 1 produces 0, 2 produces nothing, 3 produces 2.. just like with the original keyboard.
So it looks like my problem is this flaky motherboard, not the keyboard. Which I wish I'd known before I desoldered all the keys..
Oh well, good chance to clean the PCB and make sure only good keys go back in, there were a few bad ones.
But yeah.. now I need to figure out which part of the motherboard is involved in interpreting keystrokes, because that is probably where my problem is.
Look at the bright side; it will give you a chance to bring your keyboard up to spec.
Found my problem. 2 bad SN74LS257AN chips, up above the keyboard connector. Swapped them out.. boom.. everything's happy again.
Now I just need to find a source for about 8-10 replacement key switches to replace the non-working ones I have.
Having swapped those two chips appears to have brought me further along with my Disk controller too. It now makes noise and the drive attempts to boot -- but only gets as far as blanking the screen and producing the ] prompt at the bottom, then just stops.
BTW: what are my odds of finding switches like the ones my keyboard had?
Wondering if I have a RAM problem now.
Using another keyboard, I inputted: 10 Print"hi"
Then I hit enter and got this long line like: 00B9- A=FB X=FF Y=01 etc... that's pointing to a RAM problem most likely right?
That was exactly why i asked if you have viewed the Apple II Circuit Description.......
i assume you have referred to the 2 74LS257 at location B5 and B7 as displayed on page 210 in the book.....
This was the reason i recommended not to extract but just resolder the joints and then view the book.....
If you would have replied first to my question about if you have read the book - i would have attracted your view to
page 210......
it´s at the moment useless to tryout the disk unless the missing RAM at location E3 is not replaced.....
Get that step solved first and then you may proceed to use a test disk.... !
I´ve noted this order of the tasks ( #8, #11, #20 ) above !
If you want to boot DOS 3.3 you need at least complete and intact 48 kB of RAM !
If you want to boot ProDOS you will need also the complete intact language card inserted ( i.e. 64 kB RAM )
Same is valid to UCSD Pascal.
If you want to boot CPM you even will need besides intact 64kB RAM also the Z80 card inserted in slot 4 !
( unless you use the patched 44 kB CPM version )......
Even booting testdisk requires all RAM on board ( 48 kB ) to be completly inserted....
speedyG
Hello,
In case you want to test the RAM, just type the following :
]CALL -151
*C050 C053 C054 C057 N 265:FF N 266<265.
BFFEM 266<265.BFFEV 265:0 N 266<265.BFFE
M 266<265.BFFEV 34:14
You need to add a final space after 34:14 and hit Return
The test will loop forever. If numbers and letters are printed at the bottom of the screen, RAM chip(s) need to be replaced.
Hi speedy
I filled all RAM banks a while ago.. I had a pile of gold 4116s (all same speed) which had previously tested good so I removed what was in there and filled each bank including that formerly empty socket. But its seeming like a possibly bad one slipped in there.
But of course.. I think the disks I attempted to boot were prodos. So I will have to steal a language card from one of my other machines. I wonder If I should try the one that was custom built with the custom built motherboard that came with the case.
Hello Falter,
if you want to get reliable results i´d recommend first to use a known good languagecard.....
if the system passes - then the tests next step might be to test the "custom languagecard".....
you should allways bear in mind: the more unknown components you test in one cycle - the more
things might fail..... and locating mistakes it´s allways a good idea to reduce choice and possibilities....
by using reliable parts, that don´t need another testing.....
speedyG
I'm getting it figured out now.
First, to eliminate RAM as a suspect, I removed all the RAM from my Linden and put it in the Rev 04. Still would not boot properly. So then I thought, maybe it's the ROMs. I swapped them out with a complete set from my working II+ and boom! Booted right up, no problem. I did try swapping ROMs one at a time first, checking part numbers.. but in no circumstance would the system work with mixing the ROMs from the two machines. Had to swap the entire set.
So then I swapped in a single line of RAM in the first bank. I had errors. So I came up with a crude swapping system to try and nail things down. Working right to left, I removed each chip individually and subbed it with another one. If it didn't change anything, I moved to the next one, swapped the chip in that socket with the one I'd pulled, and so on. Eventually I brought in two chips from outside the original row and had a bootable machine. Now I'm going to swap in the remaining chips, one at a time into that first bank and if nothing breaks, put them in the 'good' pile to populate the second bank, and so on. Probably not the correct way to do things but the only way that makes sense in my tiny mind.
Not too worried about these ROMs as I intend to replace them with integer ROMs to get back to a more original A2S1 configuration. The only casualty of all this now is my Linden's keyboard. It stopped working while I was using it on the Rev 04, and now will not work with the 04 or the Linden. Only the CTRL-RESET and repeat keys work. Sigh. Another project I guess. But at least I'm finally getting somewhere with the Rev 04. Thanks for all the help guys, it is really, really appreciated.
Probably you hooked up the keyboard backwards once in all the swapping and burned one of both of the 7400 TTL. If you're unlucky like me, you may also have burned the MM5740AA/E, which is now nearly impossible to replace.
-Pete
If anyone needs it, I have a spare keyboard and encoder card for the II Plus. The encoder is working, but the keyboard has broken-off keycaps. So it's definitely parts-only.
This Linden keyboard is a Unitron unit. The keyboard controller chip is just an EPROM from what I can tell. Still would be difficult to find, but maybe possible to read and re-burn?
I have all the TTL chips necessary... just don't have the tools to figure out which chip is bad.
Hello Falter,
if you are ( like i made guess ) located in Germany, then send me a pm...
I´m located close to Munich / Freising near Airport.....
i have quite a bunch of empty spare Eproms and i have equipment for reading and programming Eproms....
speedyG
Unfortunately I live in British Columbia. But I'd be happy to send this off via mail and pay to have it checked out and replaced if its toast.
I've replaced most of the other chips already. I kind of think its the eprom. The only key sequence that still works is ctrl-rrset and that works whether the chip is in or out. I just dont know how to test it. But Im hoping the programming bin is out there somewhere.. unitron was a pretty prolific company from what i understand.
Hello falter,
wll BC is quite far away amd the German customs are quite lousy..... normally mail from USA to Germany wastes up to 4 weeks delay .... therefor it´s rether more recommenended to find a AF memmber close to Canadian border ( like along the "borderline" from Seattle to Denver or Chicago.....
and probabply it´s a good idea to place here 1 or 2 pictures ( at least 1 from keyboard top and bottom and at least one closeup of the area where the eprom is located with and 3 to 4 cm border including the surrounding area ) before carrying out the expenses.....
speedyG