Powerbook Duo 230 appears dead

[macman0512]

Hi guys,

I recently acquired a Powerbook Duo 230, and it seems to be dead. When I plug in the power supply and try to turn it on, nothing happens. The main battery hasn't leaked and I used my known good Powerbook G3 PSU, which has the right voltage and more than enough amperage to power it. I also checked the motherboard, and it seems dry and oxidation free. Furthermore, I tried unplugging the PRAM battery, and that did nothing as well. Does anyone have any idea what to do?

 

[3lectr1cPPC]

Even if the board appears fine, the capacitors near the DC port are probably bad. You should probably get both the motherboard and the display recapped before troubleshooting it further. That alone may very well be your issue.

 

[macman0512]

Even if the board appears fine, the capacitors near the DC port are probably bad. You should probably get both the motherboard and the display recapped before troubleshooting it further. That alone may very well be your issue.

I'll do that. Any idea what the values are of the ones on the display? I'd rather not disassemble it more than once if possible.

 

[Fizzbinn]

I recapped my Duo 230 and documented here:

PowerBook Duo 230 repair and preventive maintenance

*** This content is from a thread lost in the 6/30/2021 outage. I'm reposting attempting to include info (if not images) posted by others. *** ** @Fizzbinn 5/3/2021 ** A while ago I picked up a cheap Duo 230 with a cracked screen that was otherwise working, been on the lookout for parts...

68kmla.org

 

[Trash80toHP_Mini]

Will be following this closely, maybe start a recap thread about the Duos or have a mod change the title of this one? The little I've garnered on this near and dear subject is that failure of that capacitor can tank farm can blow out the logic board. So I've only rarely booted any of my several Duos since reading that.

@Fizzbinn you beat me to it, thanks for that link. Have you seen a/o checked out tank farm catastrophic failure reports?

 

[macman0512]

I recapped my Duo 230 and documented here:

PowerBook Duo 230 repair and preventive maintenance

*** This content is from a thread lost in the 6/30/2021 outage. I'm reposting attempting to include info (if not images) posted by others. *** ** @Fizzbinn 5/3/2021 ** A while ago I picked up a cheap Duo 230 with a cracked screen that was otherwise working, been on the lookout for parts...

68kmla.org

Thanks!

 

[Fizzbinn]

@Fizzbinn you beat me to it, thanks for that link. Have you seen a/o checked out tank farm catastrophic failure reports?

Do you mean dead Duos due to serious, visible logic board cap leaking? If so not sure I've heard/read, seen pictures about that. Something you have a link to? I think I do remember reading somewhere that dead Duos might be killed by failed caps that otherwise looked fine. That's part of what motivated me to replace mine while it was still working. (and like you I don't use the couple of other working Duos I have, plan to recap them as soon as I can)

 

[macman0512]

Which parts are most likely to be ruined if the caps are bad and you do connect it to power?

 

[Trash80toHP_Mini]

Dunno, I only remember the report and don't recall if it was detailed in that manner.

 

[mdeverhart]

Have you tried the power button on the back of the machine, or just the one above the keyboard? The one above the keyboard often won’t work if the PRAM battery is dead, but the one on the back “jump-starts” the power manager IC. You may hear a bit of a squeal when you press the power button on the rear.

The leaking caps on Duos are in the battery charging and power regulator circuits. The Duo power supply is 24V, which is stepped down to charge the battery and to other voltages for the main logic board.

I can’t find the threads now, but I’ve seen various reports of problems plus the usual issues:
1. The normal trace corrosion cause by cap goo, which might need to be fixed with bodge wires
2. Shorts on adjacent logic circuits, which may function improperly until cleaned up
3. Shorts in the power regulators, which can prevent them from starting up or running correctly. Often accompanied by a repeating “tick-tick” sound
4. Shorts between the high voltage power input / battery charging circuits and the logic circuits. This can inject 12-24V (more or less) into 5V circuits, which will often burn them out. It can also cascade into connected parts of the board, damaging components downstream of where the short originally was.

 

[Papichulo]

If the power port smells like fish the capacitors leaked and could damage the board if youplug it in again

 

[Unbounded_Villain]

Not for nothing, if you are interested in using Duos, you should buy a few for parts. They’re VERY inexpensive on eBay, and many of the parts between models are interchangeable.

 

[Trash80toHP_Mini]

4. Shorts between the high voltage power input / battery charging circuits and the logic circuits. This can inject 12-24V (more or less) into 5V circuits, which will often burn them out. It can also cascade into connected parts of the board, damaging components downstream of where the short originally was.

Thank you, that would explain catastrophic failure resulting from the Tank Farm taking a hit on power up.

 

[mdeverhart]

Yep. I think one of the common ways that happens is that the goo leaks through vias to the bottom side of the board, and I think there are some ICs in that area that take the hit.