Need help diagnosing my PowerBook 170…

[PB170]

The day that I've dreaded has come – my PowerBook 170 has started to give up…

Since I got it back in 2001, I've experienced more or less all common failures over the years, but this far I've managed to resolve all of them (internal connector issues, ground faults, failed hard drives, broken AC adapters, broken fuses, failed backlight, trackball/keyboard issues, damaged interconnect and flex cables, damaged plastics etc.), with all of the major issues occurring between 2001 and 2008, and only minor things thereafter. However, I've dreaded the day any ICs or other PCB components would fail, as that would be beyond my ability to repair. (For those of you who are not aware of it, I use my PowerBook more or less daily for all kinds of things, so I very much rely on it working.)

Fortunately, I realized my dependence on it already back in 2018 and purchased an extra PB170 to have as a spare. However, since that's the only spare I have, I would prefer to keep it intact and instead fix the issue if possible.

I've determined that the problem is with the daughterboard (where the CPU/FPU and other logic chips reside). On the positive side, there are much fewer components on the daughterboard than on the motherboard. But on the other hand, the daughterboard is populated almost entirely with large, surface mount ICs…

The problems began already in December/January, but it has mostly been working since then, and up until just yesterday I thought the problems were related to the drive that I'm using (a Stratos CF PowerMonster II from 2013 – more on that below).

At present, the issue manifests itself as follows:

• Endlessly repeating four-tone sequence as soon as the computer is turned on, directly at the checkerboard pattern (no Sad Mac-screen)
• After a cold start, the computer just sits at the checkerboard pattern without the tone sequence. Same thing happens any time the restart button is pressed. As soon as the computer is restarted with the power button the above symptom resumes.

Does anyone have any idea what faults this symptom could be an indication of?

I've done just some basic troubleshooting:

• Inspected the board – everything looks good visually
• Tried cleaning the board thoroughly with IPA and a brush – no change
• Left the computer running for a while and looked for warm chips – nothing unusual
• Tried pressing down on each IC before/during startup (only top side since the bottom is inaccessible when it's connected to the motherboard) – no change

Coincidentally, I just recently ordered an entry level oscilloscope, which might come in handy in examining the board (though the fact that the underside of the board is inaccessible when the computer is running limits the troubleshooting to the top side…).

If I'm going to be doing any desoldering of the larger ICs though, I'll definitely have to invest in a heat gun as well…

Also, having known that I might have to do board level diagnostics someday, I've gathered some useful tidbits over the years. In particular this post by register on this forum a long time ago:

[…] Be sure to use proper ESD protection when pointing a soldering iron towards the board! Also be careful when using a multimeter. Several circuits of the 180 do not like high test voltages; use a multimeter that is appropriate for use with old CMOS electronics. Some tell the 180 is built solid as a tank. This is true for the housing, but I already ruined one motherboard just by measuring a line and one daughterboard by fixing a connection.

I only have one of those cheap multimeters that are powered by a standard 9V battery. Does anyone know if these are safe to use? I guess, when I get my oscilloscope I could use that to determine the voltage applied to the probes during resistance/continuity measurements.

I really hope there's someone with expert knowledge here who can point me in the right direction

 

[PB170]

Some additional details of the gradual failure (that I thought was drive related), which may or may not give some clues:


December 23

Sudden Sad Mac screen at startup (0000000F/00000003). Then goes away.


December 23 – January 9

No issues (daily use, 2–4 hours/day)


January 9

Occasional random crashes/freezes, eventually followed by Sad Mac screen at startup

I suspect the disk (PowerMonster II / CF card) may be at fault. I open the computer and try to simply disconnect and reconnect the CF card and HD ribbon cable, after which the computer starts working normally again (used it for an hour or so).

Later that day, I'm greeted by this corrupt alert box (Swedish system):

Skivan "Macintosh CF" kan inte användas,
räff`d▯Dtt ovänt`t fdl uppstod, -127. ▯
B▯▯▯ ▯ø†©▯▯ ▯▯-™▯▯ ▯(x´▯▯ ▯\P¨▯▯
▯_≠▯▯ ▯i.

Which probably should have read:
Skivan "Macintosh CF" kan inte användas,
?????? ett oväntat fel uppstod, -127.

In English, roughly:
The disk "Macintosh CF" cannot be used,
?????? an unexpected error occurred, -127.


I start up the computer from an external drive to run a check on the drive with Norton Disc Doctor (routine thing after repeated system crashes). I then notice that the volume name is shown as "L`bhntnrh BF" rather than "Macintosh CF", but the check surprisingly completed without any errors.

At this point I assume the CF card must have started to fail.


January 10

I back up all the files on my main volume that had changed since the last backup (fortunately just 9 days old). As I'm about to backup the second of two extra volumes that I have, the copy fails almost immediately due to disk errors. Try it a few more times, but same result.

Later during the day, I try to start the computer again but is greeted with the flashing disk icon. I start up from the external drive and fire up Lido which now shows "No volumes" on the drive.


January 11

I decide to swap out CF card for an old one that I used a couple of years ago. This all seems to work fine, but after using it for a couple of hours at a café, to my great dismay, the computer freezes again.

When I get home I try to copy over an old version of the aforementioned failed volume that I had left on the old card. It chugged on for a while, but then failed with the same drive errors. The situation deteriorates further during the evening, and the computer once again starts up to the flashing disk icon. This time, Lido doesn't even recognize the CF card, and freezes when it reaches the drive (ID 0). At this point I suspect the PowerMonster itself. I open the computer once again, and try to clean all the connectors on the PowerMonster with IPA, partly reassemble the computer, but same thing.

Later during the troubleshooting process, I decide to push on the one socketed chip on the PowerMonster board (a flash memory chip in a PLCC socket) in case there might be some issue with the connections there. After that, all the issues went away, the volumes came back and the entire, previously failing 1 GB volume copied without issue! Problem solved, I thought.

I go on to reinstall the original (newer) CF card, format and partition it, and restore everything from backup.

To verify, I made a new backup and compared it with the original a week later, which showed no differences.


January 12 – February 5

No issues (daily use, 2–4 hours/day)

However, I notice that when I connect the external drive and try to start the computer, it crashes with the Sad Mac screen (same 0000000F/00000003). After a second attempt it starts up normally. So I suspect there may be two separate issues.


February 6

Sudden random crashes. After a few restarts, the computer starts up to the same Sad Mac screen (0000000F/00000003, and sometimes 0000000F/0000000A). I naturally suspect the socketed chip may be at fault again. Since I didn't have a PLCC chip remover at hand, I resorted to pouring IPA over the socket while pressing down on the chip repeatedly. After this the problems went away again and the computer started normally.


February 7

No issues


February 8

Apps begin to quit randomly and computer freezes at shorter and shorter intervals. After a couple of restarts, it eventually gets stuck at the checkerboard pattern and repeatedly plays the 4-tone sequence, as described above.

I assumed the socketed chip still had a bad connection, so I created an ad-hoc chip remover in order to properly clean the contacts. Before I did that though, I tried to disconnect the hard drive ribbon cable just to see what happened (totally thinking it would fix the issue). To my surprise it remained unchanged. I went on to disconnect the floppy drive, but same thing. At this point Apples Service Source suggest replacing the motherboard. Before I tried that though, I swapped the daugherboard with one from a PowerBook 140 that I've used as a parts machine, which got the computer working again.

And so, here I am with an apparently faulty daughterboard… (and a much slower computer…)