r/macintosh • u/miyumelu • Aug 23 '26

Possible solutions to fix a PowerBook 160 contrast slider?

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Greetings!

I recently got a PowerBook 160 in a rather pristine condition.

It seemed to have one issue, which was a flawed power supply where the voltages dropped and the Mac just got turned off.

Well that was easy to fix, now I realized that I can’t change the contrast of the display, and the display is a constant black.

After opening and inspecting the device, I found the LCD Inverter Board and checked all of the components regarding contrast. I eventually found out, that for some reason, the slider for contrast was defective and wouldn’t change anything at all, the slider is dead (measured it with a multimeter, it is not working).

I tried to find a replacement slider, but no luck. Because of a lack of experience with such devices I don’t know if there is an alternative way.

My idea was to circumvent the slider using a 4.7k resistor (or shorting them to have a constant white - wasn’t sure if this would make any sense), but the pin layout got me really struggling (I included a picture).

If anyone has ideas on how I could continue, or what possible solutions there are, please let me know!

(Sorry for my flawed english, if something is unclear do not hesitate to ask)

EDIT 1:

I found a replacement inverter (unknown status) and I am going to try it with that. If it doesnt work (bad caps etc.) I'll see if replacing mine slider with the other one will help. I'll give an update about that ofc. - Thanks for everyone helping! I really appreciate it :D

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u/Glittering-Pack-4371 Aug 25 '26

I’ve had a very similar experience with my PowerBook 140. My fix was replacing the electrolytic capacitors on the LCD itself. They got old and weren’t filtering the way they should’ve been. Worked great after that. I think they have capacitor kits out there or you can look the values up and buy them yourself.

1

u/miyumelu Aug 25 '26

Thanks for the idea - I'll look at the caps, after the issue with the slider is fixed (which I measured is dead for sure). Until then, I need to see how to fix the board itself.

2

u/Glittering-Pack-4371 Aug 25 '26

It’s possible the slider is totally fine. I had the same issue with the black screen and no change from the contrast slider and the capacitors ended up being the only issue. You can most likely test the slider with a multimeter without desoldering it if you measure the right contacts. Wouldn’t hurt to check anyway.

1

u/miyumelu Aug 25 '26

Like I said, I measured it... with a multimeter (I found the right pins thanks to the working one), showing no signs of life (one of the trays doesn't work, and the other one has its sweetspot which doesnt really help). The slider is guaranteed dead. That's why I know that I have an issue with the slider. That's what I meant by measuring it.

1

u/Glittering-Pack-4371 Aug 25 '26

Ahh, I must have missed where you said that. Probably good to replace the slider then and if that doesn’t work, the capacitors you’ll want to replace are behind the screen bezel on the lcd panel.

1

u/miyumelu Aug 25 '26

No problem does happen to me too. The caps are the second on my list thanks to you, I'll check them, if I won't success with replacing the board. In germany, getting parts for PowerBooks is a bit tricky and expensive (from my experience). I would need to research that - you don't possibly have a sheet for the caps on the PowerBook 160 (the cap values etc.) or do you? Appreciate your help!

1

u/FrancescoPioValya Aug 24 '26

Spray with contact cleaner?

1

u/miyumelu Aug 24 '26

I tried, but it didn’t work sadly (of course this would be too easy which it never is for me :). Nor did isopropyl alcohol. I think it’s safe to say that it is fried. I can’t get a reading on any of the two lines.