Notice to Powerbook Duo Users!

[register]

The notice on leaking caps on the display PCB of PB Duos reminds me to the problem of moribund TFT panels in some PB 180 machines. Did someone investigate if the display malfunction might be caused just by a capacitor leakage and therefore could be fixed?

 

[Mk.558]

I've got both a Duo Dock and a mini Dock. Shame my Powerbook is stuck in the Duo Dock and I don't have the key.
I'll just have to find me a pick gun and have at it I guess.

Use a Dremel and cut the Dock open?

 

[nvdeynde]

Yes the Minidock also need recapping. So does the PSU of the large Duodock...

 

[Mk.558]

Well...

The recap job on both of the boards went smoothly. No hitches or hiccups on the way. I was pleased.

The End!

That...is what I was hoping for. Ughm...gonna need some tantalums. Not enough room on the display inverter board. PACKED in the display board, up the left side. Oops. We'll be okay. Definitely didn't see the 47uF 6v cap (I used 25v) near the top left corner of the keyboard coming. Can't put the keyboard down. Actually went not tooooo bad...bit of a problem removing the old tanks because of the tight proximity to each other. tsk tsk tsk

Pictures...maybe tomorrow. "How many pads did you lift?" Uhmm...ugh...a few

 

[JWG Design]

Thanks for the info about problematic caps. I've got a Duo 280c that needs inspection for this problem. The full Dock had the clicking problem a long time ago, but I never replaced the PSU caps. I did not think it was an operation I could handle myself. More recently, I recapped the PSU in my TiVo DVR, and that was rather easy. The Powerbook disassembly is a bit more intimidating, but I can handle it if I can find a clean surface to work on.

Can someone tell me if these issues are symptoms of the bad caps? The Duo runs fine when the battery is inserted and the power supply is connected, but the battery is not recognized. I used to be able to trick the Duo into seeing and charging the battery if I removed it for a few seconds and then reinserting it. That doesn't work anymore. If I remove the battery, the Duo will turn off after a few seconds. The Duo will not turn on unless both the PS and battery are connected. Resetting the Power Manager does not help.

 

Also on the capacitor agenda is a couple of my Quadra 840av motherboards. Hopefully they haven't damaged the MB yet.

 

[JWG Design]

I feel like a complete dufus. It's been a while since I've posted anything on bulletin boards, and now I've managed to do it wrong. I messed up the italics BBCode in my previous post and now phpBB won't let me edit the post to make the correction. Very frustrating. I must be missing something obvious. Is it because the thread is a Sticky?

 

[digitalrampage]

I just recapped a leaky 270c but the ticking continues. Anyone kow any other common issues in the DC circuit? I did wash the area with pure Isopropyl to assist prior to install of of the new caps.

 

[OleLila]

So, as above, except with a Duo 280...I replaced the capacitors and there is still only clicking. Are there other options? I guess I will recap a second time just in case. I hate to let this thing go.

 

[bibilit]

IIRC the ticking/clicking is just a sign the PSU is faulty, can be anything from a faulty component to a short somewhere.

Capacitors problems are related to unstable voltages or outputs becoming too weak at some point.

 

[OleLila]

If I have a power supply that will boot a Duo 230, is it possible that it cannot boot a 280(and clicks on the motherboard?)

 

[AlpineRaven]

Recently obtained two PB Duo 270c - someone already tried firing up, the person I got it off said "didnt work" 

One of them has burnt resistor next to the DC jack and other one has burnt mosfet. I had spare mosfet for it so decided to replace it. Recapped it - doesnt have ticking sound but showing LED on the display bezel - havent been able to fire it up yet - is the LED good sign or not?

Cheers

AP

 

[digitalrampage]

Ticking sound was from the DC-DC circuit. if it quit ticking and is dead, thats BAAAD news :-(

After a recap my 270c is ticking from the dc-dc circuit.. any ideas what I may have done. Was dead before- heaving leaking but no damaged tracks 

 

[techknight]

DC-DC converters tick if there is no load, tripping it into overvoltage protection, or a short causing it to trip into overcurrent protection. Youll need to go chasing to find out where it is, and what condition it is in. Easiest way is to start resistence checks on the output side of the converters. 

 

[Darrell Johnson]

Update:  Refer to this post for Duo Display Recapping: