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Powerbook 100 restoration..

imactheknife

Well-known member
Any ideas what to look out for.. board was clean, did have some cap goo, but cleaned up super nice.. going to order caps from console 5. Waiting for new power supply to show up too.
 

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alexGS

Member
What voltage is on that battery? :D

Probably best to run without the battery unless it is at least somewhat close to correct 5.4-7V range. You can unclip the front of the battery (by sliding it off) and use it on the front of the Powerbook for cosmetics but it needs a bit of thin double-sided tape on the bottom to stop it falling out.

That board is all super-clean - congrats - doesn’t seem to have had any of the board mods applied except the ground wire added underneath (with the signature white adhesive).

Make sure the trackball isn’t rubbing on the circuit board under it. If it is, then consider a square of felt or some extensions to the supporting prongs, otherwise the ball can rub through a circuit trace and kill it.

Personally I’ve found the ordinary radial electrolytic capacitors have all been OK, but all the surface-mount caps need replacing. Those near the reset/interrupt switches can prevent power on or make a buzzing sound when the power is connected. The one beside the display connector can prevent sound while the two in front of the display connector can cause vertical lines. Those above/near the trackball can prevent the LCD drive voltage from being generated, giving a blscreen. Those on the back of the screen itself can give a bit more ghosting, though the main threat seems to be leaks damaging the circuit board as I think has happened to one of mine.

I managed to repair a Connor 20MB hard drive (just like yours) last week that had the ‘sticking heads’ problem; I was so happy. I used some of that UV-cured resin (‘Bondic’ brand) to fill in the slot where a tab on the head arm parks. No need to disassemble any part of the head movement mechanism! So don’t discard really old/useless hard drives - they are quieter than some Quantum drives anyway :)

Oh - one more thing ;)
Both of my PB100s had the same fault preventing the backlight from working - except one was fixed by me and the second one the same fix by someone else. R257 supplying Q39 (transistor near the display connector) goes open-circuit. It is a 430k resistor. A standard 476k axial resistor can be bodged into place and works (as shown), but I’ve just enjoyed fixing it properly with a new surface-mount resistor. We won’t ask why R256 is actually a capacitor…
 

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imactheknife

Well-known member
Cool, thanks for the response! There is caps on back of display? Ok, will do that when cap kit arrives.

Not sure of battery voltage as i dont have a charger yet, it’s coming too.

Will check trackball and see. Rubber around display was good, so no damage to screen thankfully!.

Not sure state of drive, will have to wait until it powers up after recapping computer.

will keep posted of progress:) my first vintage mac laptop restore.
 

alexGS

Member
Cool, thanks for the response! There is caps on back of display? Ok, will do that when cap kit arrives.

Not sure of battery voltage as i dont have a charger yet, it’s coming too.

Will check trackball and see. Rubber around display was good, so no damage to screen thankfully!.

Not sure state of drive, will have to wait until it powers up after recapping computer.

will keep posted of progress:) my first vintage mac laptop restore.
I guess it’s a blessing in disguise when the trackball wears down its support posts and sinks into the assembly; as it does, it helps protect the screen :D

Enjoy the restore! Perhaps do all the logic board capacitors first, since the screen seems to still display even when its capacitors need replacing (just degraded image quality)

The capacitors on the back of the screen are a challenge to remove because they are within a plastic frame. It is quite a major disassembly to get that frame off; the backlight diffuser has to be lifted off and one of the sheets is annoyingly stuck to the LCD. It can be really risky to tilt the frame as it can crack the thin LCD corners where they touch. I ruined the first one; number 2 (shown here) went much better, and number 3 has some other weird ghosting fault that I don’t know how to fix.

So, if the solder joints are clean-looking like in the first photo below, I suggest desoldering the caps without taking that frame off/disassembling the LCD. Hopefully the leakage underneath the caps will be limited and easily cleaned up with a cotton swab dipped in alcohol. If the leakage is widespread then I guess you’ll have to take apart the LCD anyway, since the cleaning solution can easily seep into the backlight diffuser if you apply a lot. The result looks like Godzilla has invaded the LCD.

I’ve used 0605 MLCC caps to replace those 3.3uF electrolytics. They are easy to fit with the frame in place (third photo below) but are absolutely tiny, smaller than they need to be. Easy enough to solder one side first while holding with tweezers, then the other side.
 

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Wawavoun

Active member
Hello there,
I have a Powerbook 100 fully recapped (including screen and inverter).
Everything is ok including the screen but the brightness control (the one at the right) is not working at all. Turning it dont change anything in the display.
Is this situation also related to R257 ?
Thanks for any advice.
Regards.
Philippe
 

alexGS

Member
Hello there,
I have a Powerbook 100 fully recapped (including screen and inverter).
Everything is ok including the screen but the brightness control (the one at the right) is not working at all. Turning it dont change anything in the display.
Is this situation also related to R257 ?
Thanks for any advice.
Regards.
Philippe
Do you mean that turning the brightness knob to the left does not dim and turn off the backlight?

If R257 is open-circuit; the backlight will not be working.

I think the situation of having the brightness stuck at maximum is probably not too bad :)
 

imactheknife

Well-known member
I guess it’s a blessing in disguise when the trackball wears down its support posts and sinks into the assembly; as it does, it helps protect the screen :D

Enjoy the restore! Perhaps do all the logic board capacitors first, since the screen seems to still display even when its capacitors need replacing (just degraded image quality)

The capacitors on the back of the screen are a challenge to remove because they are within a plastic frame. It is quite a major disassembly to get that frame off; the backlight diffuser has to be lifted off and one of the sheets is annoyingly stuck to the LCD. It can be really risky to tilt the frame as it can crack the thin LCD corners where they touch. I ruined the first one; number 2 (shown here) went much better, and number 3 has some other weird ghosting fault that I don’t know how to fix.

So, if the solder joints are clean-looking like in the first photo below, I suggest desoldering the caps without taking that frame off/disassembling the LCD. Hopefully the leakage underneath the caps will be limited and easily cleaned up with a cotton swab dipped in alcohol. If the leakage is widespread then I guess you’ll have to take apart the LCD anyway, since the cleaning solution can easily seep into the backlight diffuser if you apply a lot. The result looks like Godzilla has invaded the LCD.

I’ve used 0605 MLCC caps to replace those 3.3uF electrolytics. They are easy to fit with the frame in place (third photo below) but are absolutely tiny, smaller than they need to be. Easy enough to solder one side first while holding with tweezers, then the other side.
Thanks much for your help! Appreciate the pictures and experience you have had. Hope if goes well. I am waiting for caps now, so maybe a week or two before any progress on it now..

Will open up display and see
 

joshc

Well-known member
Wow, those are dinky little caps.. well, always up for a challenge!
Tweezers are your friends! My hands are not super steady, probably not bad but I found working with small components daunting at first but tacking down one side of the capacitor while holding with tweezers, using flux to make sure the solder goes where you want, and working fast with the iron helps. I follow the soldering techniques used by Branchus Creations: https://www.youtube.com/c/BranchusCreations
 

imactheknife

Well-known member
Tweezers are your friends! My hands are not super steady, probably not bad but I found working with small components daunting at first but tacking down one side of the capacitor while holding with tweezers, using flux to make sure the solder goes where you want, and working fast with the iron helps. I follow the soldering techniques used by Branchus Creations: https://www.youtube.com/c/BranchusCreations
I am much better than I used to be! so should be fun! Yes, learned a lot from Branchus, especially cleaning pads with solder wick and flux..love that
 
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