PowerBook 5300C repair help :)

[iPhil64]

Hi all !

I just get a PowerBook 5300, sold for parts on eBay.

The overall external condition is pretty good, at least all plastics are nice (broken hinges for the door at the back), not broken, not scratched. Battery has died long ago. and the rubber feet... are nasty.

The machine did chime a few times, but the screen has always been black so far. Pressing on the machine clearly made it obvious that there were bad contacts everywhere.
Looking closer, I could notice that the machine had been disassembled, but most parts were really not well remounted, so I decided to fully take it apart.

Tearing it apart, it appears at some point there was some leakage, but I think it got fixed (AA mentioned on the serial number sticker). The chassis has some traces of liquid (from the battery compartment), but the motherboard itself is in very good condition (see pictures). One of the pins leading to battery has completely corroded, but I'm not sure this will be an issue. You will also spot some traces of corrosion on the connector to the floppy bay for instance.

The barrel jack was very loosely soldered to the motherboard (by the way, who ever designed such a small part for such a critical plug was really mad), so I desoldered it, but honestly, it does not seem very solid.

I cleaned all connectors, and reassembled the machine, which, this time, was perfectly remounted (I'm lucky not plastic is broken).

Now when replugging, the green LED comes, but it never chimed again so far. I hear scratches in the speaker that's all.

Do we have a reference for the power barrel jack ?
Any advice on the order of troubleshooting ? This seems like a good candidate for Marchathon...
Is it advised to recap it as a start ? I haven't seen much about the 5300c yet...

PS: I'm pretty sure the disk has died long ago, but that I will look at that if the machines chimes again and turns on the display.

 

[rikerjoe]

FWIW, I have not recapped my PowerBook 5300cs. I took mine completely apart for cleaning and inspection about a year ago. The electrolytic cap on the logic board looked fine (no bulging or cap juice) and the same with the cluster of caps on the DC board. I opted not to do a recap yet.

The DC barrel jack is crap. I had an extremely poor connection from the power supply to the PowerBook that improved somewhat when I desoldered the barrel jack and reinstalled it with gobs of fresh solder.

Do you have the memory expansion module? I recall having boot problems if it wasn’t seated properly. I have a second module from a parts machine that has a bad memory chip on it somewhere and the PowerBook won’t boot at all with it installed. Double-check the display board and DC board to ensure both are seated properly. I’m sure you removed the dead PRAM battery, too.

Good luck in your troubleshooting. My PowerBook 5300cs was my daily driver for five years, and restoring it was simply a bit of nostalgia for me.

 

[3lectr1c]

My first bet would be the DC power board (module with all the caps on it), they do go bad from what I've heard. I've had abnormally good luck with my 5300 units, both at least booted correctly (though had power-unrelated issues). I've got mine mostly recapped now (just gotta get one cap on the inverter board changed), but the power board is done. So yes, give it a recap.

Here's a link to some cap reference info on my website: https://macdat.net/cap_reference/apple/powerbook/5300c.html
I've got to add a couple things to it though, so I'll mention them here for now:
1. There is only one 2.2uf cap, I left the amount out for some reason. Also make sure to get a tiny replacement! It's a very small electrolytic, I ordered some tantalums and they were too large.
2. Get the smallest diameter 100uf caps for the power board that you can! Otherwise you won't be able to get your soldering iron in to solder them all in. I went with some Wurth caps on mine.
3. I bought the whole lot of caps for the Sharp LCD display for mine, only to open mine and find that my 5300c has a Toshiba screen with no electrolytic caps at all. Verify the model of yours before ordering if you're planning on doing the whole thing!

I'll be overhauling my 5300 capacitor guides soon with images and such.

If recapping the power board doesn't get it going, it's possible that something else has failed on it. Check for corrosion again in that case.

 

[iPhil64]

OK @rikerjoe and @3lectr1c , thanks for your initial thoughts.

My first culprit is most probably the barrel jack, since it did chime before I completely tore it apart, and the green LED has always shown up.

Now when pressing on the keyboard, the speaker cracks, so definitely a lot of bad connections, I will disassemble again, especially with all the evidence of previous leakage.

@3lectr1c I think I will recap the board, as this is the main board that took leakage. Now it looks relatively clean, so it may have been replaced.
@rikerjoe Yes, I do have the 32 MB board, I will just remove it for now. When I received the machine, most connectors were not properly seated anyway.

I also haven't probed any voltage or signal. Is there a 5300c schematic available somewhere ?

It really seems I have some work ... But hey, this is what we love.

 

[iPhil64]

So, I just took off the three screws again, and plugged it in one more time and... it chimed, with everything else untouched, including the memory card.But the barrel jack is the number 1 culprit.

Any reference for this ?

 

[rikerjoe]

I have not looked for a replacement jack yet. Perhaps @3lectr1c has some insights?

 

[iPhil64]

By the way, you can have a look at the boot sequence :

 

[3lectr1c]

If it’s chiming then I doubt the barrel jack is at fault honestly, it either gets power or it doesn’t. I’d be looking toward the power board.

 

[Yoda]

...and the green LED has always shown up.

This is odd, I think. The green LED should not normally light, except to flash every second when the 5300 is in sleep. I don't think it has any other function on this system - normally.

I may have misunderstood what you're describing, but it sounds like the Green Light of Death if it's coming on when the 5300 is connected to power, and the system is otherwise unresponsive. Pressing reset on the back (the button under the video out port) normally resolves this in an otherwise healthy machine.

The jack could be at least part of the problem if there's a broken solder joint. It could be enough to establish a circuit, but not to carry the current required to run the machine. 5300s are notorious for this kind of issue.

 

[3lectr1c]

That is the GLoD. Yes, check the power connector again, but the power board is also known to be at fault for this.

 

[iPhil64]

OK thank you all.

The barrel definitely is not a good contact, but once in a position power does flow.

I took a second look at the power board, and a few caps are definitely not flat on the top. Not very visible at first glance, but suspicious. I will inspect more and recap. Also I need to look at the other board at the back.

The reset button does work, and will make the LED come black, then chime, the come green, and... nothing.

 

[3lectr1c]

The caps on both my working power boards did also look slightly bulged, probably a sign of age and impending failure. Luckily they don't seem to be leaking (yet), just drying out hopefully? Get them replaced and it may come back. You probably have one or more out of spec power rail due to it.

Here's a thread I did on the MLA when I recapped one of my boards: https://68kmla.org/bb/index.php?threads/powerbook-5300-power-dc-board-recap.40394/

 

[iPhil64]

The caps on both my working power boards did also look slightly bulged, probably a sign of age and impending failure. Luckily they don't seem to be leaking (yet), just drying out hopefully? Get them replaced and it may come back. You probably have one or more out of spec power rail due to it.

Yep.

I haven't found any documentation or schematics, do we have any on that line where we could know what to probe ?

 

[3lectr1c]

No info on what to probe unfortunately, board-level diagnostics is where my skills reach their limits. I'd just recap the board and then troubleshoot further from there. Your issue a one known to be caused by bad caps.

 

[iPhil64]

Did find this : https://archive.org/details/service-apple-manual-powerbook-190-5300

At least gives some high level troubleshooting guidelines.

 

[iPhil64]

As a followup, I ordered caps to replace them all on the power board.
In fact, after closer inspection, I do believe that some of them may have leaked, but somebody cleaned it a bit.

Also, the connector was really dirty due to the old battery leakage. See photo below of before and after cleaning.

I've tried to find a replacement for the battery connector as well both on Digikey and Mouser, but no luck yet.
5-pins connectors do not seem to be a trend anymore ! Anyway, this is less urgent since the battery is dead anyway.

 

[3lectr1c]

Ooh, yeah, that’s an issue. Might want to give that another cleaning and touch up the solder joints.