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PB 5xx original AC adapter re-cap & modern replacement

Fizzbinn

Well-known member
*** Originally posted 5/31/2021, reposting due to outage. Thankfully the text was in Bing Cache. ***

The PowerBook AC Adapter (M1893) I got off eBay worked for about 2 days, at least I now know the "sold for parts" PowerBook 540c I got earlier works (and came with a 32MB RAM card!) Getting out the multimeter VMAIN was reading only 2 volts when it should be ~16 volts. VBATT was still 16 volts not that it maters since I don't have any working batteries.


pb500-ac-adapter-pinout.png

So surprise (not), it looks like the AC adapter was in need of recapping. At the same time I really want to figure out (and document) a way to power PowerBook 5xx series without an original AC adapter, which seem to be somewhat less easy to find (and pricier) than other PB AC adapters.
 

Fizzbinn

Well-known member
First up, recapping the original AC adapter. There are a bunch of threads here with advice on this.

<Links lost>

The bottom line seems to be there are no screws in the AC adapter case, opening one up can be quite a challenge, and/or quite easy since the plastics are often so brittle... In my "case" I just gently but firmly squeezed the sides on the seams all the way around and the plastic split along them after a few passes.

Some cracked case pictures:

IMG_1459.jpg

IMG_1460.jpg

IMG_1461.jpg

And the AC adapter internals, note you need to desolder a blob holding a metal shield to a pin on the bottom to be able get to the underside:

IMG_1458.jpg

IMG_1456.jpg

PowerBook AC Adapter (M1893) electrolytic capacitors:
(used for PowerBook 520/520c/540/540c/550c)

C1, C2 - 100µf | 200V d:16mm h:26mm
C14A, C14B - 100µf | 25V d:6mm h:11mm
C308A, C308B - 330µf | 25V d:8mm h:20mm
C802 - 47µf | 25V d:5mm h:11mm

Note: C802 is on a daughter board you need to remove to get at. In my case C14A, C14B, C308A, C308B and C802 showed signs of leaking.​

M1893-PB500-AC-adapter-caps.jpg

Next up find replacements on Mouser...
 

Fizzbinn

Well-known member
Switching to the modern replacement, the connector seems to be the biggest challenge. I spent a couple hours looking and couldn't find anything that looked like it would be even close to mechanically compatible. Its like a Mini-DIN connector, but with a custom pinout. To make it even harder the AC adapter cable's connector is female and the Powerbook's is male, the reverse of what you usually see...

IMG_1485.jpg

It seems others have sacrificed their old broken AC Adapters, stealing the cable to graft onto a modern adapter. I guess if my AC Adapter recapping fails I may end up at the same place but I stumbled across a somewhat hacky idea using something that could connect to a single pin. Originally I tried a female Dupont connector breadboard 1-wire jumper but the diameter of the pin on the PB was to large. Further looking I found D-Sub Female Crimp Pins that fit!

IMG_1488.jpg

IMG_1489.jpg

Instead of cutting off the barrel connector from my new AC adapter and soldering these on I decided to create an adapter of sorts.

The 16V 4.5A 72W AC Adapter Charger for IBM ThinkPad I got has a DC CONNECTER SIZE: Internal Diameter: 2.5mm, External Diameter: 5.5mm

So I also got this 5 Male + 5 Female DC Connector Barrel Power Jack, 5.5x2.5mm to use as a breakout (plus spares!). I also decided to use some heat shrink as an insulator for the D-Sub crimp pins.

IMG_1491.jpg

And this is what it looks like all put together:

IMG_1492.jpg

And plugged in, one cable at a time, to the PB VMAIN (black/16v) and GND (white/ground) pins:

IMG_1493.jpg

...but now I'm getting cold feet on actually powering it up (decided to work on this post while I think about it!). I'm wondering if it really is okay not to connect up something VBATT or GND Sense, it seems like leaving out VBATT should be safe, especially considering I have no working batteries that I'd want to charge. GND Sense seems like it could be more important though, I can't seem to find any info specific to the PB 500 series but for other PowerBooks it looks like it might have some specific resistance value to ground? that powerbooks use to determine what type of AC adapter is connected to them.

Anyone know or have thoughts?
 

Fizzbinn

Well-known member
@kalleboo's post (not sure how I missed it in my searches before) has given me some confidence to give it a try!

<link lost>

I especially like the idea of being able to power it via a USB-C battery pack, but it doesn't solve the Powerbook connector issue, @kalleboo used the cable/connector from their dead original AC adapter.

So after seeing @kalleboo didn't connect anything to GND Sense, I decided to reassemble my PowerBook 540c and give the new adapter a try.

...and success!


IMG_1494.jpg

It's certainly not super quick to connect up but it also is not too bad connecting the two wires D-Sub female connector wires. You certainly have to know which pin they need to go to: left side, voltage on top is pretty easy to remember.

I know nothing about 3D printing but I wonder if it would be possible to come up with a barrel shaped D-Sub female pin holder?

So it seems VMain (pin 2) and GND (pin 3) are all that’s needed to power up.

Perhaps GND Sense (pin 4) was optional, something for future use? In newer PowerBooks a sense pin/contact seems to tell the PB how much power it can draw, 45w vs 65w adapters, etc.
 

demik

Well-known member
Good work !

Not sure what the GND Since is for either...
On a side note, PB5xx (without a battery) can work with only 12V. The 540 logic board that I have works just fine with 12V from an ATX Power Supply.
 

MacUp72

Well-known member
I bring this up because I'll get a 540c soon but without a power adapter.
Apart from this solution above I wonder how the original power adapter actually works, I mean from looking at its pin layout:

stecker.jpg

There are two 16,5V Pins, one main for the board and one for the battery charge, but are these two actually galvanically separated inside the power brick itself? I mean 2x 16V or one 35V mains from the brick and then separated lines inside the cable to the pins?

For a quick test you could just measure Pin 1&2 if it reads 0 Ohms ..

If it is just one main 35V you maybe could solder in a more standard Pismo G3 45W socket (with some additional pin soldering)
 

3lectr1cPPC

Well-known member
I do believe that they are two separate lines. I can test pin out myself tonight if you’d like but when I got some batteries for my 500 series systems, my AC adapter got significantly warmer in different areas and eventually became unstable (thanks old caps… gotta change them). At the very least it causes significantly more load on the supply.
 

MacUp72

Well-known member
and you use the original brick( maybe just recapped)? and yes, it will get warmer, especially with two batteries inside charging
 

3lectr1cPPC

Well-known member
I haven’t recapped mine yet. I’ve got to. It also got warmer in different spots though. Usually only one side heats up but both got toasty with batteries
 

3lectr1cPPC

Well-known member
Mine were partially working (would keep the system in sleep mode) but are now cracked open and awaiting rebuild. I don't have them working right now but you just wait ;)

I already have a working 100 series battery at the moment too. Some people do still have working batteries!
 

MacUp72

Well-known member
hm, the 540c doesnt want to boot up..I improvised a power adapter of sorts for pins 2 and 3 and I also can measure the voltage on the pins inside the board, it is getting 24v..( I resoldered an older 24V Pismo adapter) but no green light on top of the display. Maybe the fuse F1 is blown?

IMG_1306.JPG
what kind of fuse is this LF , 'little fuse' 7 Ampere..is this a quick or slow?
 

croissantking

Well-known member
hm, the 540c doesnt want to boot up..I improvised a power adapter of sorts for pins 2 and 3 and I also can measure the voltage on the pins inside the board, it is getting 24v..( I resoldered an older 24V Pismo adapter) but no green light on top of the display. Maybe the fuse F1 is blown?

View attachment 56899
what kind of fuse is this LF , 'little fuse' 7 Ampere..is this a quick or slow?
Probably a quick fuse, I would guess? Can you test continuity?
 

MacUp72

Well-known member
I disassembled it and tested the fuse, its ok I guess, it has continuity.
I will now try to fabricate a power supply with a universal, voltage adjustable power adapter..
 

MacUp72

Well-known member
ok, I found an interesting genuine auto part that I thought could be useful for fabricating an alternative, more stable version of the above solution.it is quite impossible to find ANY connector with a squarish pin layout similar to the original PB's power cable..its size is near 6,5mm in diameter, similar to mini DIN (ike for old audio devices) but the pins are different.

I found this cable for car dash reverse cameras, it has almost exactly the same 4-pin layout as the Apple power supply, so I just ordered one.
Bildschirmfoto 2023-05-24 um 15.29.21.jpg

dont buy these from china, these are too small, their diameter is just about 4mm instead of 9mm.

Bildschirmfoto 2023-05-24 um 16.59.01.jpg


then I clipped of the outer 12mm metal union nut and filed the connector down a bit to 6,5mm, its easy, it is soft plastic.
after a while I had this, it now fits into the powerbook, it powers up.
(The only disadvantage is its 4 cables inside are quite thin, because they only transfer data, but it works)


IMG_1339.jpg
 

croissantking

Well-known member
This is quite impressive.
Which power adapter are you using to boot the 540c?
I am interested in creating a USB-C charger for my PowerBooks, I have seen it been done.
 

MacUp72

Well-known member
I bought an 15-24V adjustable Hama universal adapter like this:

h.jpg

but I think this one is very similar:

h.jpg

I considered buying the newer versions but these are controlling the voltage internally, I prefer to set it manually by switch .
 
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3lectr1cPPC

Well-known member
Hey @Fizzbinn! I'm going to purchase caps for my 5xx supply that's in need. Just a couple questions:

1. Are there any specific ESR or high-frequency requirements for these? I know some PSUs can be picky about that stuff, and this is my first time doing one.
2. For the two big ones, should I buy regular radial leaded, or the snap-in style?

Thanks!
 
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