Apple II (rev1) instability...HELP!

Discussion:

(too old to reply)

Nama

2011-04-07 05:57:10 UTC

Hi all,
Me again.
I've recently sold one of my Apple II, and I am moving all my cards
over to another rev1 Apple II that I own.

I'm trying to find out why this system works fine 90% of the time,
while the other 10% it crashes and hangs or just displays odd
behavior.

Setup is as follows and is identical to my previous machine:

0 - Ram card
1 - CFFA #2 ( (prodos 1.1.1 / contiki))
2 - SSC
3 - empty
4 - Uthernet
5 - Echo 2
6 - Floppy I/O
7 - CFFA #1 (turnkey startup to DOSmaster 1.7)

Of course I have tried the system with minimal cards and it still
exhibits weirdness.

Symptoms:
-Sometimes hangs on boot.
-Strange inverted period often seen in top left corner when booting
from CFFA #1
-Sometimes craches to the monitor
-Doing a IN#1 to launch the CFFA #2 always hangs with a strange
flashing inverted period in the top left corner. often with corrupted
type on the prodos launch screen.
-Once it up and running it's usually fairly stable unless I reboot.
-Have run a looping game for many hours with no problem, but crashed
to monitor as soon as I restart.

What I have done:
Tried a new set of ROMs
Run Apple test utils on the RAM and ROM...no problems found.
Run the machine from a known good IIe power supply.

If anyone here can shed some light on my problems, I would be very
grateful. I'm hoping the inverted period may be a good clue to whats
happening.

I've uploaded some bad photos here if this helps at all:

http://web.me.com/lord_philip/apple_1_%26_II/rev1.html

Much thanks in advance.

Phil

Nama

2011-04-07 14:33:20 UTC

Permalink

Post by Nama
Hi all,
Me again.
I've recently sold one of my Apple II, and I am moving all my cards
over to another rev1 Apple II that I own.
I'm trying to find out why this system works fine 90% of the time,
while the other 10% it crashes and hangs or just displays odd
behavior.
0 - Ram card
1 - CFFA #2 ( (prodos 1.1.1 / contiki))
2 - SSC
3 - empty
4 - Uthernet
5 - Echo 2
6 - Floppy I/O
7 - CFFA #1 (turnkey startup to DOSmaster 1.7)
Of course I have tried the system with minimal cards and it still
exhibits weirdness.
-Sometimes hangs on boot.
-Strange inverted period often seen in top left corner when booting
from CFFA #1
-Sometimes craches to the monitor
-Doing a IN#1 to launch the CFFA #2 always hangs with a strange
flashing inverted period in the top left corner. often with corrupted
type on the prodos launch screen.
-Once it up and running it's usually fairly stable unless I reboot.
-Have run a looping game for many hours with no problem, but crashed
to monitor as soon as I restart.
Tried a new set of ROMs
Run Apple test utils on the RAM and ROM...no problems found.
Run the machine from a known good IIe power supply.
If anyone here can shed some light on my problems, I would be very
grateful. I'm hoping the inverted period may be a good clue to whats
happening.
http://web.me.com/lord_philip/apple_1_%26_II/rev1.html
Much thanks in advance.
Phil

I love replying to myself...there is some satisfaction in knowing that
you solved a problem.

THE FIX (as far as I can tell) ...Replace faulty 74LS138 @ H12

From my symptoms I figured there was something up with the slots. With
nothing in any of the slots the machine seemed to run ok with no
crashes on power up. So I decided to shotgun replace the IC's that
were closes to the slots and seemed to have something to do with them.
Within 15 mins I had found the culprit.

Can anyone enlighten me as to what 74LS138 @ H12 does? In the
schematic is says I/O selects, but I'm not sure what exactly that is.

Phil

mwillegal

2011-04-07 18:52:02 UTC

Permalink

Post by Nama

I love replying to myself...there is some satisfaction in knowing that
you solved a problem.
From my symptoms I figured there was something up with the slots. With
nothing in any of the slots the machine seemed to run ok with no
crashes on power up. So I decided to shotgun replace the IC's that
were closes to the slots and seemed to have something to do with them.
Within 15 mins I had found the culprit.
schematic is says I/O selects, but I'm not sure what exactly that is.
Phil

A few days ago, t posted scans of Apple's hobbyboard doc on my blog.

http://www.willegal.net/blog/?p=1447

There is a separate I/O select for each slot, except 0. It is often
used
to select the last 256 bytes of each peripheral card's ROM.

Regards,
Mike Willegal

Nama

2011-04-08 00:17:28 UTC

Permalink

Post by mwillegal

Post by Nama

A few days ago, t posted scans of Apple's hobbyboard doc on my blog.
http://www.willegal.net/blog/?p=1447
There is a separate I/O select for each slot, except 0. It is often
used
to select the last 256 bytes of each peripheral card's ROM.
Regards,
Mike Willegal

Mike, thanks again for the reply.

Just a quick update: Seems I haven't fixed all the issues yet. There
seems to be a heat related issue somewhere. Upon a cold restart (after
the machine has been off for some time), the computer will crash into
monitor right after displaying the 'APPLE ][' text. successive
restarts seems to allow the boot process to get a little further. If i
leave the machine on for a minute or so, the next reboot will work
fine and from that point on the machine seems good.

This issue maybe a little trickier to find, but for some reason I
suspect RAM, don't ask me why, it's just a gut feeling.

Phil

Antony Mauget

2011-04-09 05:57:32 UTC

Permalink

Hi Phil,

Post by Nama
This issue maybe a little trickier to find, but for some reason I
suspect RAM, don't ask me why, it's just a gut feeling.

In that case, a simple trick can help you : swap RAM chips in rows C and E.
But based on the description, I don't think it's a RAM issue. Anyway, you
can give it a try before going further.

--
Antony
Apple II forever

Nama

2011-04-09 10:24:08 UTC

Permalink

Post by Antony Mauget
Hi Phil,

Post by Nama
This issue maybe a little trickier to find, but for some reason I
suspect RAM, don't ask me why, it's just a gut feeling.

In that case, a simple trick can help you : swap RAM chips in rows C and E.
But based on the description, I don't think it's a RAM issue. Anyway, you
can give it a try before going further.
--
Antony
Apple II forever

Thanks for your thoughts Antony,
I did spend a few hours today swapping around RAM, and also swapping
out my Saturn 128k memory card for a standard language card. I'm not
sure exactly what chip was bad or weather it was a problem with the
128k card, but I seem to have fixed the issue. Fingers crossed that
the problem doesn't return.

Phil

Michael J. Mahon

2011-04-09 23:04:39 UTC

Permalink

Post by Nama

Post by Antony Mauget
Hi Phil,

Post by Nama
This issue maybe a little trickier to find, but for some reason I
suspect RAM, don't ask me why, it's just a gut feeling.

With all the Apple ][ chips in sockets, it's all too common for contact
oxidation to lead to instability--particularly temperature-sensitive
instability.

Just removing and reseating chips is often all that it takes to get
back to stable operation.

-michael

NadaNet 3.1 for Apple II parallel computing!
Home page: http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

Nama

2012-04-23 13:47:59 UTC

Permalink

Sorry to resurrect such an old thread.
I am still having big issues with this machine. It's a very early rev 1 board whose serial number is around #12000. It even has the dark green slots like in the later REV 0s (not the super early REV 0 light green ones).
Since I got it it has never been very stable as you can see from the above postings, however it did seem to settle down after a while. Well the Apple II has been in storage for about 2 years and I recently pulled it out as I have moved into a new place with enough room to do hobby stuff again. The flakiness has returned, and worse than ever. Initially the machine wouldn't boot from the CFFA and often came up displaying the random character screen, not sure what I did, but I got it working for a while, then it stopped again. Now I can't get either of my CFFA cards to boot. I have removed all the cards except the Language card and the CFFA card in slot 7. The machine either hangs at the 'APPLE ][' prompt, or crashes into monitor when trying to boot from the CFFA. Very very occasionally it may start the boot process, but crashes soon after. If I put the card in slot 6 I seem to have a little more luck, but not much. In slot 5 the boot process sometimes seem to get a little further but ultimately crashes. I've tried the CFFA is all the slots, and slot 7 seems the most difficult. Slot 1 and 2 display the message "Can't load PRODOS" which is kind of promising I guess.

I have reseated all the IC's multiple times now. with little or no change. and previously (a few years back) in desperation I had swapped in and out IC's from another working II+ motherboard to try to find faulty IC's.

At one point the machine just started showing random characters. so I started to suspect bad sockets. I broke out my continuity meter and after some time I found a pin on the 6502 that didn't seem to be making a good connection. I removed the CPU and carefully spread the legs apart and reinserted it. The random characters screen disappeared and I got The 'Apple ][" prompt again.

Now for the weird bit. The other cards mostly seem to work ok. I'm not 100% sure about this yet as I need to do a little more testing and moving cards around. The Carte Blanche in slot 5, 4, 3 and 2 boots and works fine but does not work in slot 6 or 7. The floppy card in slot 6 works fine.

Anyway, I'm kinda stumped. I've been messing with this system for about 4 hours (or 4 years if we go way back) and I can't see any pattern that I can lock into. One thing worth mentioning is as this is an earlier machine the internal motherboard mounting allow for more flex that the later models as it has fewer mounting posts. Maybe this flexing overtime has caused some issues. The board is presently out of the case and sitting flat on my workbench.

Any advice would be greatly appreciated. I would really like to get this Apple II up and running as It'll need to be my workhorse machine now that I sold off many of my other Apple II's.

Philip

Philip Lord

2021-05-16 23:38:53 UTC

Permalink

Follow up (many years later)...it's an issue with a cold solder joint or bad socket. Slight flex to the board produces anomalous responses. No fix yet, need to look into it further

Oliver Schmidt

2021-05-17 09:29:27 UTC

Permalink

Post by Philip Lord
Follow up (many years later)...it's an issue with a cold solder joint or
bad socket. Slight flex to the board produces anomalous responses. No fix
yet, need to look into it further

Back them I witnesses someone using cooler spray to locate a bad connection
pretty precisely.

Michael J. Mahon

2021-05-17 23:00:17 UTC

Permalink

Post by Oliver Schmidt

Back them I witnesses someone using cooler spray to locate a bad connection
pretty precisely.

Probing the board with a non-conducting probe can also be quite effective.

--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com