powerbook AC adapter disassembly.

[techknight]

Has anyone taken apart the big gray brick yet? this one is the 7.5v 2.0a for the PB1xx series.

I had one that was damaged in shipping, so I was going to crack it open to see whats inside, until I found out that I see no screws!

any ideas?

 

[Macdrone]

Yes it is snapped together with 1 screw under the sticker. I forget where I'll try and look. I took one apart last year, I think I still have the shell, I kept the cord in case I found a good 7.5 volt power supply.

 

[techknight]

Well i want to correct the shoved in prongs. Plus lets face it, its SMPS based design and will eventually need recapped.

mine is an M5651/APS-20U

Edit: I dont see a screw? I cant feel it.

 

[Macdrone]

I cant find the old case. I know it has one as when I pryed it apart it was stuck in the center and I snapped the leg for it to get it apart. I am sorry tho I don't have it anymore.

 

[techknight]

I just peeled the sticker off, nothing there :-(

So i guess its possible that certain models/versions had it, some didnt. This one doesnt.

 

[Macdrone]

Weird. I know the portable power supply did not have a screw but its tight together and same type of plastic.

 

[Paralel]

Power supply with no screw? Hot knife it.

 

[techknight]

Yea, thats one thing I dont have. So i guess ill redneck it

 

[didius]

any succes?

 

[techknight]

nope. NEver could crack it apart. I am going to have to break it apart.

 

[nvdeynde]

I used a small saw to open the adapter. Anyway, the enclosure can't be used afterwards. There's quite a bit of electronics inside for a regulated PSU.

I also notice that all my PB100 adapters are going away from specs, that is giving too much voltage. Most of them give about 7.8 to 7.9 volts, which is too much is you want to use the powerbooks with a working battery as it never charges fully. The powerbook's charging circuit shuts down too fast.

You get the symptom that the powerbook stops charging after less than 45 minutes while normally for a rebuild 4200 Mah Nimh battery it would take at least 2.5 hours with a 2A adapter when it's drained.

When I use my lab PSU, set to 6.5 volts and 2A max current, then the powerbook batteries do charge fully in about 3 to 4 hours.

So the original power bricks are for me just a collectors piece as they can't be used to charge the battery anymore.

It's sort of weird as the white 1.5A adapters from the Mac portables are even older, however these output exactly 6.5 volts and charge well too.

It can probably be solved by recapping the adapter and adjusting the voltage but you can't do that without destroying the enclosure...

 

[techknight]

You pretty much hit the nail on the head there. I do think they can be recapped and feedback network adjusted but the adapter will look like shit when done. My 520c is black taped lol. But it works now

 

[didius]

Okay, I cracked one open.

It is possible to open it without damaging the case to much. Perhaps I could glue it back together?

Don't forget to remove the one screw:

The inside of mine looks messy.

What do you think? Fixable? What should i get?

 

[techknight]

What screw? I dont see a screw. That is an incredibly well built SMPS power supply, something youll NEVER see these days. (chinese garbage, noisy junk). Even has full common-mode filtering, etc.. Its just lacking an EMI shield.

Anyway, Its easily fixable. Just recap it, and then check the output. Those pots adjust the output current and output voltage.

 

[didius]

@techknight

There's a tiny screw beneath the wire on that location.

Anyway, here's an image with the caps on the board and their specs.

http://s7.postimg.org/f1jmgr7yj/HPIM3731_edited.jpg

I had a leaking 16V 1200uF, so I've replaced it. Furthermore I replaced the 16V 180uF with a 35V 220uF.

Then I've tried it again, output directly on the motherboard starts at 8.5V, and after a minute it's 5V and it keeps dropping. What's going wrong?

Should I replace the other caps to?

I bought some other caps but there aren't a lot of electronic shops in Belgium. I was given this:

instead of 50V 47uF => 63V 47uF

instead of 16V 82uF => 25V 100uF (CapXom :-x )

instead of 400V 47uF => 400V 100uF (to big, doesn't fit)

I guess i should buy my caps online...

 

[uniserver]

my guess is the voltage regulator.

 

[techknight]

That probably uses a TL431 shunt regulation circuit for the feedback, but I dont know Your pictures are too small and lack detail.

First off you need to replace the capacitors with exact values? this is an SMPS application, alot less lenient on capacitance changes. RC Osc networks are formed, feedback filters, and more importantly dead-time control, and restart circuits are based on the capacitance values.

Also the caps HAVE to be low-ESR type, required for SMPS applications.

 

[didius]

I've ordered all Panasonic Caps low ESR online, hopefully they arrive soon.

I've been measuring a bit of voltage yesterday.

Input is fine constant at AC 230V.

After passing the "S1WB" rectifier i measured constant DC 320V.

Here's a picture with all the paths:

http://s23.postimg.org/hqigegyq3/HPIM3731_edited2_small.jpg

And some bigger pictures:

http://s22.postimg.org/vluasnmap/HPIM3738.jpg

http://s9.postimg.org/hljuivti7/HPIM3740.jpg

The voltage regulator sits on the side, next to the 1200uF 16V, it has the part number: D10SC9M

But first I'll wait for the caps to arrive

 

[techknight]

Thought so, it uses the TL431 shunt regulator. (behind the pots) Replace that too. If this drifts, you loose regulation. You can hit it with a can of freeze-spray, or poor-mans freeze spray (can of air upside down) and if the voltage shoots to one direction, its bad.