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PowerBook Duo 280c no chime

glay78

Well-known member
Powers on light lid, no chime, no HDD activity and LCD not lit. What could be wrong?

I’ve already unplugged the PRAM battery and tested with or without ram. With or without HDD. Even tried resetting the power manager. 
 

 

androda

Well-known member
Could be capacitors, could be battery leakage. These old 68k laptops often need capacitors replaced, with the leakage causing potentially a lot of random issues.

 
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glay78

Well-known member
Could be capacitors, could be battery leakage. These old 68k laptops often need capacitors replaced, with the leakage causing potentially a lot of random issues.
There isn’t battery leakage, could be caps I’m suspecting too

 

glay78

Well-known member
try unplugging it while holding the power button, then plug it back in and attempt to power it on.
It doesn’t works, sometimes the light will turn off. Press power, lights on but nothing happens. Sometimes the light turn on and blink once every few seconds

 

Challenger 1983

Well-known member
as others have said it is most likely caps, I would suggest replacing the ones near the DC jack first and verifling that the problem is solved before tearing the display assembly open and attempting to recap 

 

glay78

Well-known member
Yes I think so too, just feeling weird, this board is actually a spare part unused but kept in storage for 20+ years. Even unused the caps will leak? Sigh 

 

Byrd

Well-known member
... is there a reason why it was shelved NOS for 20 years?  Might explain the GLOD (green light of death), a common issue with many PowerBook Duos and usually not related to caps.  Check also the output of your PSU and any SMT fuses near the DC jack.

 

glay78

Well-known member
... is there a reason why it was shelved NOS for 20 years?  Might explain the GLOD (green light of death), a common issue with many PowerBook Duos and usually not related to caps.  Check also the output of your PSU and any SMT fuses near the DC jack.


I bought a couple of PowerBooks all from storage, none of them works just good as parts. There is this box of spares for 230 and 280c duos, both NOS. Even has top plastic and rubber sides new. So I tried mixing them around to get it work. For the 230 it makes screeching noise when powered on. Nothing just noise and that seems like caps leaking problem.

I’ll check the fuse in a while.

 

glay78

Well-known member
Also only 1 of the 5 x duo charger from storage works. 1 or which still gives smoke when plugged in. 

 

glay78

Well-known member
as others have said it is most likely caps, I would suggest replacing the ones near the DC jack first and verifling that the problem is solved before tearing the display assembly open and attempting to recap 
will a faulty display prevent it from powering up?

 

glay78

Well-known member
Found U23 one of the pin has no continuity, I soldered a wire over and it chimes and startup now showing flashing disk. 
 

however this isn’t too stable, after a few tries it stops powering up again. Will take a look at it again later.

404F3806-098B-4059-AD61-FF2D115DF77B.jpeg

 

glay78

Well-known member
Alright time to recap after fixing the broken trace. I smell fish...even this board is new it has been in storage for 2 decades, once it powered up it leaked.

will need to hunt for a new display too. 

FDDD4FFE-8C07-472A-A06D-60359127E1FD.jpeg

 

androda

Well-known member
Yes indeed, the capacitors will leak whether they were actually powered up or not.  So NOS parts, still sealed, never used, stored properly... can still come right out of the bag with capacitors leaking and corroded traces on the board.  Sigh.

 

glay78

Well-known member
Yes indeed, the capacitors will leak whether they were actually powered up or not.  So NOS parts, still sealed, never used, stored properly... can still come right out of the bag with capacitors leaking and corroded traces on the board.  Sigh.
you are right, this is a spare part board and it still leaked. Look at the leak. 
 

E6F1DB8B-748F-439D-82C2-E150F93EE776.jpeg

 

aplmak

Well-known member
You should also recap the display! This is a tricky job. I'd follow the Apple take apart procedures to remove the top cover of the display. I use a small needle to get under the screw covers and gently move around to get the plastic covers off the front. Be careful not to bend or stick the needle in the delicate plastic covers. I then rub all the old sticky glue of and use scotch double sided thin tape cut to size. Once you start unscrewing with a T8 I think it is, the screw mounts will fall apart. I use JB Weld 2 part epoxy and rebuild an entirely new mount with the metal screw anchor in the middle. It's a very tedious job but in the end you get really strong mounts. Once the cover is off the top you can access the display and remove the plastic white covering over the display and get to the caps.. There are like 10 small caps.. I replace with all Tantalum. Also you have to remove the inverter board and replace one capacitor on that. Typically these caps don't leak so this is an option if you want to do this! If your not confident enough I would NOT perform this recap job. I've done tons of them. If you have a spare machine maybe test your skills on another one.
 

macuserman

Well-known member
You should also recap the display! This is a tricky job. I'd follow the Apple take apart procedures to remove the top cover of the display. I use a small needle to get under the screw covers and gently move around to get the plastic covers off the front. Be careful not to bend or stick the needle in the delicate plastic covers. I then rub all the old sticky glue of and use scotch double sided thin tape cut to size. Once you start unscrewing with a T8 I think it is, the screw mounts will fall apart. I use JB Weld 2 part epoxy and rebuild an entirely new mount with the metal screw anchor in the middle. It's a very tedious job but in the end you get really strong mounts. Once the cover is off the top you can access the display and remove the plastic white covering over the display and get to the caps.. There are like 10 small caps.. I replace with all Tantalum. Also you have to remove the inverter board and replace one capacitor on that. Typically these caps don't leak so this is an option if you want to do this! If your not confident enough I would NOT perform this recap job. I've done tons of them. If you have a spare machine maybe test your skills on another one.
Based on the melted plastic around the base of the "new caps" in the photo above I'd say it might not be a job to tackle without a little more practice.
 

glay78

Well-known member
I'm better with soldering iron, not air gun. These big caps were soldered using air gun and its my first time using it. My subsequent or infant all other recaps are done with soldering iron and tantalum caps are they are smaller which gives more space to work on. I've recap a PowerBook 180c LCD to work before so recapping the LCD definitely is doable but I don't see the need yet on this 280c but maybe my 2300c as I can see slightly flickering on my LCD.
 
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