Powerbook 170 PSU Clicking?

[switch998]

Ok, so I'm not quite sure where to start on this project. I recently bought a busted 170 from eBay, from what it looks like it was used overseas by the government because it has a bunch of declassified stickers and a TON of sand in it. Of course it didn't boot on my first attempt, so I opened it up, cleaned it out, and attempted to power it up again. Still nothing, so I took out my multimeter and measured the voltage on the power supply.

From what it looks like, the computer attempts to power up, then cuts the power and tries again -- if I listen closely I can hear my power supply clicking for this reason.

Does anyone have any advice on where to look? I read the diode near the power jack is a problem, so I replaced that to no avail. I also don't have a battery, so it wouldn't be that.

 

[uniserver]

you have to take the power brick apart and change all the caps in there. they have gone bad and that is why the psu is clicking.

 

[switch998]

Wish that was it, but I tried three different power supplies, so that's not the issue. I should mention the PSUs work normally with other powerbooks

 

[uniserver]

try a 3.0 amp

maybe the hd is bad, causing an over draw on the system.

 

[finkmac]

The same thing was happening with my PowerBook 180 logic board, the weird click/squeak noise was coming from the Power Adapter.

I swapped in the motherboard of a semi-functional PB165, and it disappeared. It has something to do with the motherboard.

 

[switch998]

Yeah, it's definitely the motherboard, I disconnected all of the cables and daughterboards and it still has the same problem. I think I'll give this board a cleaning, and then just randomly start poking around in the PSU area since it seems to me like there's a short somewhere in the system. Anyone have a schematic for this system, replacing some of the unmarked resistors and caps is going to be a bitch if not.

 

[finkmac]

On both of the boards, I noticed a dark spot below the Power Plug area… Maybe that's related?

 

[James1095]

Sounds like something is shorted on the motherboard somewhere. I'd start by removing any non-essential stuff like drives, memory upgrades, etc. If it still does the same thing, start testing for shorted diodes and transistors, particularly around the power supply area on the motherboard.

 

[techknight]

I fixed my 180c that had the same ordeal. One of the diodes in the dc-dc circuitry behind the power jack had shorted. Its an smd DO-214 type shotkey