PowerBook 180 won't boot

[feeef]

I have been very lucky to find a PowerBook 180 with a screen that doesn't (yet) suffer the tunnel vision issue. However, after manipulating it (mainly to work on the BlueSCSI) it now refuses to boot. It makes the normal chime and straight after, it makes the chime of death while the screen remains dark.

The original drive was dead so I installed a BlueSCSI inside. I had to open it several times to setup the SD card correctly and ended up having issues with the cable between the up and bottom part of the laptop. That affected the display and the keyboard. I ended up finding an angle where the cable would have a correct connection. At that point the PowerBook was almost usable but kept crashing randomly. Crashes were a lot more frequent when using the network through the BlueSCSI WiFi feature. The browser would always crash after 1 or 2 minutes.

Today, I transferred some files from another Mac to the PowerBook through Appletalk with the WiFi connection. After the transfer completed, I tried to open an app and it said that there was no more memory. Closing the dialog box made the laptop to crash. I tried to reboot but I keep having the chime of death after the normal chime.

I tried removing the RAM expansion card and even the BlueSCSI, but I keep getting the same result.

I noticed some time ago that the power socket was a bit lose in the inside and moving the cable could power off the device, so I made sure I had the laptop always sitting flat on the desk with nothing touching the cable. However, could a bad connection from the power socket damage something on the board?

Thanks for your help anyway, that is a great machine that I would like to repair.

 

[A24A]

As a very first step, it is probably wise to reflow the DC power socket connection. Also, you may want to rule out anything BlueSCSI or system software related by using a Network Access Disk 7.5 floppy as a startup disk in the internal floppy drive.

 

[feeef]

Thanks for your reply @A24A ! I have tried removing the BlueSCSI but the laptop doesn't go past the state of searching for a bootable device. The screen doesn't display anything. It remains dark.

When the crash happened, I realize that there was something on my desk, that I pushed behind the laptop and it touched the power cable. Now I fear more and more that my flaky power socket grilled something on the motherboard. I even have a brand new socket to replace it and I am paying the lesson of procrastinating.

Could there be a fuse on the board to protect it against this kind of issue?

 

[GRudolf94]

If it chimes, it is very hard that it'd be a power issue stemming from the socket. Do make sure that it's solid anyway. Does the programmer switch work fine? As in, measuring it with the machine open, is it consistently open when not pressed?.

Are you in a place subject to static buildup? (Dry, carpeted, etc) - and if so, did you take appropriate precautions to not zap anything while working on it?

If yes, going from there, I'd start measuring voltages. Sadly there's no schematic for the 160/180, but some approximation can be found in the 140/170 one that's floating around.

As a (purely anecdotal) datapoint, the one time I had a 180 do this, it had one misbehaving rail stemming from a randomly corroded via that ended up making the main digital logic supply sometimes spike and cook RAM and a few other parts. Started with a crash, became a random sad chime, then fully dead. That was painful to troubleshoot.