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Guide: How To Repair PowerBook 1xx Series PSUs

Spode

Active member
I've seen there are recap guides out there but sometimes these things are beyond worth repairing and I wanted to offer an alternative that has the same net result - a working PSU that looks original.

Two of my three PSUs weren't working. One of them did nothing and the other would charge a laptop but wasn't enough to allow it to boot up. They both tested very low voltage, but then so does my "working" one, so unsure if they would measure differently under load.

The PSU is glued together unfortunately so you will need some force to get it open. Some suggested putting a screwdriver under the power cable and levering from there. I did not have any success with this, and all I did was damage the casing slightly and risked damaging the wire. Another approach is to use a vice to prize it open. This seems like the best method, but my workshop is out of action right now so I couldn't get to my vice.

The final method, is to smack it with a hammer until it opens up like some sort of PCB piñata. This is what I opted for. I used a decent sized rubber mallet and with the PSU on top of carpet, I just smacked each section until I felt it start to come apart. From there, I could just pull it open.


Once inside, there is a single screw hidden underneath the DC cable - unscrew this and you can lift out the whole PCB.

It was at this point, I found that multiple components had become detached from the PCB - ripping the traces off as well! I would not recommend the mallet method if you intend on repairing the original PCB. On one of them, it was easier to count the number of components NOT jiggling around on the PCB. I did start by repairing the traces and reattaching, but I quickly stopped when I realised how much work there was to do - plus one of the coils had ripped off and I couldn't find a replacement part.

Instead, I went on Amazon and ordered a generic AC/DC PSU. This one did 7.5V / 2A, which matched the output of my devices (PB 145,160,170). I believe some models require 3A, so make sure you pick the right one. I got them on offer for about £9.99 and the brand was "SoulBay". I had successfully used one of these before, so was happy enough it would do the job.


Here you can see the modern replacement side by side with the original - plenty of space to work with! Before doing anything, I tested that it in fact worked (and I would do for at least 24 hours - you will void any warranty after this point!). Two screws held the thing in place and then it popped open nice and easily.

On the original PCB, I opted to desolder the mains cables, as well as the DC output cable. If you're feeling lazy, you could just as easily snip them off and re-tin them.


Here's inside the new device - as you can see the PCB is tiny and there is even a USB charging port! Not sure I'd have much use for that though, especially wanting to keep the vintage feel, so I'm going to just leave it hidden. I desoldered the wires from the PCB for the AC in and DC out, leaving me with just the PCB.


There was a filter cap (I assume?) bridging the AC supply which I removed. It may well have been fine, but the new supply didn't seem to need it and I didn't think there would be a big benefit in leaving it in. I then soldered the wires back in place.

Before going any further - it was at this point, I plugged everything in to test it was working as expected. I realised I had got the polarity on the DC line reversed, so please ignore this picture if you are using it as a guide - the white wire should go towards the outside of the PCB and the black on the inside. The PowerBook PSU is centre positive. This means if you stick the positive (red) probe from your multimeter in the middle of the DC jack and the negative (black) on the outside, you should read around 7.5V, not -7.5V.


Once I had corrected my wiring, I went to look at attaching the PCB inside the board. I had run out of hot glue sticks (I had enough for a single blob) so I ended up using some Loctite "Extreme Glue" which is apparently shock resistive. I used plenty of it and then using a G-Clamp on the transformer, I held it in position to the plastic case over night. By the morning it was clear it wasn't going anywhere! However, just in case it was going to come free - I put some black gaffer tape over the mains wires so I didn't make a short. The wires were already protected with a plastic boot - but they didn't seem very effective and could themselves come loose.

After this was done, the final thing left to do was glue them back together. I took a knife and cleaned up the inside slightly as where they separate you can end up with some leftover plastic that won't make for a perfect facing. I then used Super Glue (cyanoacrylate - Crazy Glue in the US I think?) on these seams and put the PSU back together.


Voila! It's impossible to tell that anything has changed, and my PowerBooks are very happy indeed. I hope this helps someone.
 

avadondragon

Well-known member
You know I'd actually thought about doing this once but never got around to it. Now I feel inspired to get out the old power pack that failed after recap and give it this treatment. As many of the classic power supplies we can keep in circulation the better IMO. In fact I wonder if it wouldn't be better to just routinely replace the PCB with something newer rather than going the recap route. Seems easier.
 

Spode

Active member
You know I'd actually thought about doing this once but never got around to it. Now I feel inspired to get out the old power pack that failed after recap and give it this treatment. As many of the classic power supplies we can keep in circulation the better IMO. In fact I wonder if it wouldn't be better to just routinely replace the PCB with something newer rather than going the recap route. Seems easier.
I was under no impression it was a unique thought!

I would argue this is certainly simpler - most people can solder 4 wires, plus it's a guaranteed fix. You can't always assume the caps are the problem - you can spend time replacing them and it still doesn't work. It then requires quite a bit more electronics knowledge to diagnose a PSU fault.

I think generally speaking with a restoration, one tends to try and keep as much of the original as possible, so this does go against that paradigm. I guess it depends on your goals. For myself, the aesthetic is identical and that's good enough for me!
 

mmu_man

Well-known member
I can't find it back but I recall seeing a video recently showing how to open these kind of things using a rubber mallet but with some heating involved, with a hair dryer, and then gently hitting it for quite some time. I suppose a hot air gun from a distance would do as well.
 

Spode

Active member
I can't find it back but I recall seeing a video recently showing how to open these kind of things using a rubber mallet but with some heating involved, with a hair dryer, and then gently hitting it for quite some time. I suppose a hot air gun from a distance would do as well.
My first one, I hit quite hard and the damage was so bad I broke the magnet on the transformer clean off. On the second one I tried to be as gentle as possible and still broke multiple components off. Even with heat applied, I just think it's more shock than they were designed to handle.
 

Byrd

Well-known member
It might be lost, but the "pencils in a vice" method referred here previously works well in cracking open the case without significant damage.
 
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