PowerBook Duo 230 not working

[mitchW]

I got a Duo 230 in unknown state. When I powered it on, it worked, but it was unstable. I then examined the capacitors on the board and found that every one of them was leaking, so I replaced them. The Duo turned then on and it worked for a half an hour or so, but when I tried to power it on second time, it failed.

It is dead, and something clicks in the DC-DC area of the board for a few seconds, then it stops. It looks that the board is drawing a lot of current, since as I plug in the charger, it sparks a bit. Also the LT1171CQ regulator IC next to capacitors gets very hot after a minute, so hot that it started to melt flux that was present from the factory...

I checked all the my recap work and even did it again with another batch of capacitors, but the issue remains. As far as my knowledge goes, I believe that there must be something wrong with that IC or the something that controls the IC... but I don't have a clue.

 

[mitchW]

Update: I took of the LT1171CQ IC and now it works. Sort of. It chimes, but it only gets to the white screen without a cursor or insert disk icon...

There is, however a nasty whine for a few seconds when I plug in the adapter.

 

[CC_333]

Try replacing that IC with a new one. I would suppose it needs to be there, which is why it whines and fails to completely boot.

c

 

[mitchW]

I replaced the IC with a new one, and now it works correctly. It still whines for a second or so, but I believe that this is normal.

But, now I discovered that the display flat cable is broken, as I can't adjust the contrast (it goes only up, but not down).

Is there a way to repair the cable? There are only 2-3 vias that are broken.

I also found out that a SMD wirewound resistor .1 ohm WSC-1 is open. It is connected to the battery and it seems it was used as a fuse. This probably explains why the battery wasn't charging.

Can I replace this resistor with a jumper wire?

 

[techknight]

repairing FFC cables arnt exactly easy. The only thing I had come up with is slightly sand down the kapton to get to the bare copper, and fix it with a conductive pen. But even that is touch and go. 

Easier to run wires around it by soldering point to point on both ends. 

Jumpering the resistor probably wouldnt be a good idea, because it could be a fusible resistor, BUT it could also be the current-sense resistor for the machine to monitor battery condition and charge levels. 

 

[mitchW]

I drew the line too soon. It actually doesn't work correctly. It will chime, but I only get a white screen with no pointer (even in the Duo Dock, so it isn't the LCD cable), and the hard drive won't spin.

The PRAM battery is missing, but I doubt that this will cause these symptoms.

So I am out of ideas, could be anything else that I could test?

 

[techknight]

White screen? or the typical "grey screen" 

 

[mitchW]

Grey screen. The one that usually shows pointer and the happy mac/insert disk icon. Sadly, I don't get either of these.

 

[techknight]

Ok. The SCSI controller or ASIC is at fault here. Ive seen this once before. Do you get a chime? Youll also notice the HDD doesn't spin up either.

Ill have to dig in my stash. I may have a logic board. Youll need a new one.

 

[mitchW]

You are bang on. I get a chime. The HDD won't spin.

I do have a dead LC III board (battery leakage). Perhaps are chips interchangeable with Duo?

 

[techknight]

I cant recall if they are or not. Take a peek. Should be a 53c96 or something thereabouts.

 

[mitchW]

I changed the SCSI chip, but it still doesn't work. So I guess I would need a new motherboard. However, this PB 230 also has a dead keyboard, a LCD with delamination problems and a broken LCD latch. So I guess it's more or less just for parts...