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Re: Help diagnose dead //e?

Brian Bernstein wrote:

On Jul 17, 10:36 pm, Wayne Stewart <waynejstew...@gmail.com> wrote:


Your picture is exactly what you get if you have no processor
installed. You likely need a replacement 65C02 but you could check to
see if the Rocketchip isn't loose. Maybe it wasn't fully seated when
installed and has worked it's way loose.

On Jul 17, 6:01 pm, Brian Bernstein <brian.bernst...@gmail.com> wrote:









I recently pulled my old Apple //e out of storage and the three shoe boxes of disks to archive data via ADT. Everything worked great until I left it running unattended for 3 hours. It looked frozen and Control-Reset wouldn't do anything.



It seems like the machine was freezing up but is now frozen. After the first failure, I was able to turn off the machine for a bit and then it'd work for a bit, but then it'd freeze again. Sometimes I'd see the "Apple //e" boot banner but nothing, or just a blank screen. Sometimes I'd get to a prompt and it'd blink a while and then the cursor would just freeze. Now when I turn it on, I just get a strange pattern on the screen (see link)



http://dronefone.com/nntp/dead2e.jpg



Before I start pulling lots of things out, a few thoughts:
1. It was plugged in through the old Kensington System Saver. No reason to think it is failed, but this should protect against minor power spikes. It had this for years.



2. It has a 5MHz RocketChip accelerator (direct 65C02 replacement). It was on fast mode at the time. I don't think heat was ever an issue with this machine. However, perhaps it fried and the pattern is what a //e would do if it had no CPU installed?



3. It had all 8 (7+aux) slots populated. Removed a Micromodem ][ and a serial card and it didn't make a difference.



4. ADTpro was connected using a SSC clone (simply labeled "Serial //" but obviously has SSC ROM since "IN#2 / Ctrl-A" reports "APPLE SSC:"). This card has worked FINE for years, but even after removing it and dropping it into my IIgs it hasn't worked again.



I'm thinking it is either the power supply or Rocketchip. Not wanting to swap parts out just yet, but I figure the screen shot would help.



Any ideas? I really want to get my old friend working again!



thanks!



I gave it a shot tonight and replaced the Rocketchip with the original
65C02. No luck.

A thought... any chance maybe the clock crystal could freeze or go
bad? I'm just thinking this could have happened since it did work last
week and then would just freeze after a period of time (shorter and
shorter periods each time until it stopped working altogether). I
could probably hunt the internet for a schematic to figure out where
the main clock crystal is, but any tips would be helpful :)


The crystal is at the left front corner of the main board.  It is a
14.31818MHz crystal--but this is not your problem.

Since the video generator is still functioning, the clock generator
of your machine is still functioning.

ISTR that there is an Apple II diagnosis guide on the web somewhere...
It would be good to find it and follow the steps to isolate the
source of the problem.

Diagnosing a dead board is one situation where an inexpensive logic
probe can be very useful.  It could, for example, quickly verify
whether the 6502 was receiving a clock signal, a reset signal, etc.,
and whether a signal going into a gate is making it out the other
side, and why or why not.

-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."