PowerBook 100 weird display

[finkmacunix]

Hello macrumors,
I have this PowerBook 100 that would start up to the Question Mark Disk icon.
I finally bought a SCSI Terminator and Disk Mode Cable, but when I turn on the PowerBook, I hear the death chime and the screen is obscured… I can see the faint outline of a Sad Mac…
How can I fix this?

 

[Intell]

My guess is that the SCSI terminator and/or the Disk Mode Cable is doing it. The internal hard drive might be dead or not have an OS on it.

 

[finkmacunix]

I don't have the SCSI cable attached, and the Hard Drive appears to have no Data on it, since It used to display a ? Floppy Disk Icon…

 

[wickedking94]

Could it just be bad wiring to the display?
Or a Bad Graphics Chip? (or whatever older computers use for graphics)

 

[finkmacunix]

Doesen't look like the monitor cable is broken…
Any suggestions on a better place to ask for help?

 

[Meyvn]

Doesen't look like the monitor cable is broken…
Any suggestions on a better place to ask for help?

Don't listen to agentphish; you've come to the right place; this is a huge community. It just may take some time, because most of us have expertise more in the area of newer Macs. You could always try local computer repair shops too; particularly long-standing ones.

I'm no expert in this area, but I do know if you need parts, Allmac.com is a great resource for older, harder-to-find stuff. And http://www.jagshouse.com/classicrepair.html Has a lot of common troubleshooting techniques.

 

[MacTech68]

Looking closely at the larger image, it looks like the first line is 00000002.

This should indicate a memory error. If you have additional memory installed, remove it and try again. If the problem goes away, carefully re-fit the module and try again.

The memory module is at the extreme left of the motherboard. The following page may help:

http://www.kevinomura.com/powerbooks/powerbook100/

At the age of this machine, it could be anything causing the memory error. It looks like a bit may be stuck somewhere (hence the odd display).

 

[finkmacunix]

Mine doesn't have one of those…

 

[chrismacguy]

My guess would be either bad logicboard RAM, or a bad display inverter board. (The Sad Mac tends to suggest its the RAM on the board itself if the slot is empty).

 

[finkmacunix]

So… I have to replace the logic board?

 

[dmr727]

So… I have to replace the logic board?

I'd start by opening her up and removing the memory module (assuming yours has one). This will force you to reseat the video cable too. Boot it with just the base 2MB of RAM and see if that fixes anything. If not, then yeah - it's probably gonna require a logic board replacement. If that ends up being the case, it might be easier to find another whole PB 100 - and that way you have spare parts too.

 

[MacTech68]

Whilst I suspect a bad RAM chip on the logic board, it could be another case of leaking surface mount electrolytic capacitors etching tracks.

 

[finkmacunix]

I'd start by opening her up and removing the memory module (assuming yours has one). This will force you to reseat the video cable too. Boot it with just the base 2MB of RAM and see if that fixes anything. If not, then yeah - it's probably gonna require a logic board replacement. If that ends up being the case, it might be easier to find another whole PB 100 - and that way you have spare parts too.

I figured I'd need another PB100…
Mine Doesn't have a RAM expansion card…
All it has is the CPU/Memory Daughter Card…
I already opened it up, and tried to reseat the video cable…

 

[Strimkind]

I figured I'd need another PB100…
Mine Doesn't have a RAM expansion card…
All it has is the CPU/Memory Daughter Card…
I already opened it up, and tried to reseat the video cable…

You could find a replacement Daughter card on ebay. That may solve the bad memory issue.

 

[toolbox]

I found this intersting link yesterday, what your having with your PB is kinda the same thing i am having with my old se/30

http://inbox.apana.org.au/?p=1342

Seems to be some capacitors that are causing it. It causes loss of sound / Video.

 

[finkmacunix]

I think my mac classic has SimasiMac as well…
However sometimes I am able to boot it to the desktop and use my apps…
Maybe it is the daughtercard, because there are RAM chips on it…

 

[finkmacunix]

so, it's been a while. 13 years, in fact. but, I finally figured out the issue.
after a complete clean and recap.. the machine was still doing more or less the same thing.

video corruption... I figured I should investigate the video circuit.

U9. SRAM used as video memory. Looks kinda grody in the picture, but cleaning didn't help.
I checked all the connections in the video circuitry and everything checked out... strange.

on a hunch, I used a hot air station to remove U9 and I swapped in a spare I had removed from a PowerBook 140 CPU board....

bingo. no more death chime and it booted to the ? disk. success!

finally, after 16 or so years of owning this thing... it works!

hopefully this helps someone out there! 🤣