Help needed with Powerbook 100

[TimR]

Hi, I could do with some expert advice on a Powerbook 100 I have.

About a year ago I recapped the screen panel and partially recapped the mainboard in my Powerbook 100 and got it working. I didn't clean the whole board, just around the caps with IPA and cotton buds.

Around 6 months ago I tried the Powerbook again, it still worked fine, but the trackball didn't function until I attached an ADB mouse. I could remove the ADB mouse and the trackball then carried on working.

Tried it again last weekend, but trackball still not working, also keyboard now not working, and no repsonse to ADB mouse or keyboard. I figured I'd change the few mainboard caps I missed originally 1xSMD 4.7uF and a few through hole 100uF etc. I powered the unit up post-recap and it still worked as before: boots from BlueSCSI but no response from keyboard or mouse.

At this point I decided to ultrasonically clean the mainboard, as the unit has progressively declined over time, so this could be a rotting trace or via? So I ultrasonically cleaned the mainboard and daughterboard for 3 minutes each side, and now it's worse! I just get the a poorly Mac bong and the attached photo boot screen. Error codes 0000000E and 0000FF00 I think they're bus error codes? I downloaded the PB100 schematic PDF, but would appreciate someone who knows more than me telling me where to look first. Not sure how I can test the processor and ram on the daughterboard with a scope while it's sat on the mainboard upside down.

Also, if anyone has spare PB100 mainboard and daughter board for sale for a reasonable cost please message me, I know there are lots out there with knackered screen panels.

Thank you.

Tim.

 

[3lectr1c]

Can you post hi-res photos of your board? Sounds to me like you may indeed have something broken somewhere. Using a system with old caps installed (if any) can accelerate corrosion. It's certainly possible for an ultrasonic cleaner to break already weakened connections.

 

[TimR]

UPDATE: I solved this problem. I bought another Powerbook 100 and swapped the daughter cards around, this fixed the sad Mac error so I knew the daughter card with the processor , RAM and ROM on it was the issue. I used the pointy end of pair of tweezers to push each of the legs sideways on the ROM and RAM chips , and one of the legs on the last RAM chip moved. So I resoldered that and the daughter card works fine again. It bongs and tries to boot normally again.

I just need to find out why the Trackball and keyboard and external mouse keyboard stopped working now. I guess that's going to be the ADB circuit. I've also found a circuit diagram PDF for the Powerbook 100 online since the original post.

The other Powerbook 100 has been recapped and that works fine too now. The plastic on it is more brown than gray though - anyone know if you can retrobrite gray plastics too?

 

[3lectr1c]

I do believe that you should be able to retrobrite the PB100 plastics. They’re the only main plastics on a gray PowerBook to yellow too. The keyboard and some other small parts can yellow on later ones, but the main plastics only do on the 100.

 

[TimR]

Further update. The Powerbook 100 with the keyboard/mouse issues works perfectly if I unplug the internal trackball - the internal keyboard works and an external ADB mouse works. If the internal trackball is attached, the keyboard and external ADB don't respond. Tomorrow I'll try swapping the trackball assembly around from my other Powerbook 100. I've already recapped both trackballs. Very close to having two good Powerbook 100s. I've also bought another from eBay UK in the last few days to recap and sell on.

 

[TimR]

Update: swapping the trackballs around fixes the issue with the original Powerbook 100. I've tested the resistors and capacitors on each trackball next to each other and they all match. Some different results on the two transistors (1AM) and four diodes (BAV99), so I spent around $5 on them from eBay and will swap them. If it's not that then the 42C60P5625 ADB chip is probably the issue. Having a spare machine definitely helps with trouble-shooting.

 

[TimR]

Update: Changed the two SMT transistors, no change. Also then changed the four SMT diodes and it works again! One of the microswitches for the top button doesn't work, but the bottom button does. I'd already desoldered and resoldered the microswitch as it seemed inconsistent. Might try stripping it down or will look for something with same footprint.

 

[TimR]

This microswitch looks like the same footprint : https://www.ebay.co.uk/itm/195956821401?var=495808884160

 

[TimR]

To anyone following this thread, the eBay microswitches arrived and although they sent the wrong ones - right angle pins and a lever arm over the switch - I snapped off the lever arm and bent the pins straight, and the trackball now works 100% again. The one with the lever arm is also an exact match for the other microswitch used in the Powerbook 100 trackball.

 

[TimR]

Hi, further question on this subject. A different Powerbook 100 trackball. Replaced all the usual suspects and still no up and down movement on the trackball. Desoldered the Infra Red transmit and receive LEDs either side of the little spin wheels and lifted off the black plastic bracket. There's mess to be cleaned up and the legs on the red LED that does up and down movement are rotten. I'm going file back to the base on the LED and solder wires on and replace, but does anyone know what the part name is, or part number?