PowerBook 540c Restoration Project

[alexGS]

Well if anyone would like to send me a working battery for free, I'd be happy to test that out

Fair enough maybe if I had more than one… I guess I can test it myself though. I have a power supply that’s just gone POP yesterday, has a short somewhere that’s not the MOSFET or the transformer-thing (but caused one of the transformer pins to arc) - this seems difficult to fix, so I’m considering other power supply options. Not to hijack the thread, but we do seem to be working on the same things at the same time!

 

[3lectr1cPPC]

I'm planning on rebuilding my own batteries once I get a spot welder. May be a while though.

 

[jmacz]

The calibration always seems to take a complete discharge/recharge cycle, or two, for EMMPathy to show the measured capacity in mAh. The default after a reset is 1752, mine seems to have come down to 1680. What’s yours?

Mine is reading 1752 in EMMpathy.

What's weird is if I run Lind, it will correct all the errors. And testing it later, continues to show no errors. Even across shutdowns, reboots, leaving everything disconnected for a while, all good. But the minute I run EMMpathy, and then run Lind again, it will report a couple errors and the tool corrects it and then it's all good again until the next time I run EMMpathy. I'm guessing the two tools aren't compatible? Lind has something in the preferences to toggle compatibility with Apple's tool so I'm guessing these tools are writing things to memory that the other tool doesn't like?

Meanwhile I’m having a search to find whether anyone with a working battery has connected VBatt and VMain together (to use a replacement power supply). We’ve had people running the machine off VBatt (instead of a dead VMain) and we have people with USB-C PD-supplied VMain, but I don’t think anyone has run the machine and charged the battery with VMain and VBatt both from a single source?

I've got a working stock charger, and I've also got the one I made for myself which like the stock one uses two 16V power supplies. So I can't really test the single source.

As for the Sleep problem, have you tried that ‘sleep fix’ extension that I think came with EMMPathy? I‘ll check my machine soon. I also wonder if that might be hard-drive related, since spinning up the drive and waiting for it to become available seems part of waking up.

Hmm... ok, I'll have to look into this.

 

[3lectr1cPPC]

IIRC the sleep fix was to prevent a battery drain bug.

 

[alexGS]

Thanks for the insights, especially the notes about conflicting ‘errors’. For what it’s worth, neither of my batteries pass the EMMPathy or Lind testing/programming (yes, the memory is probably faulty) but this doesn’t stop the batteries from working well enough for me - they charge and they run the machine for an acceptable time (1.5-2.5hrs depending on power saving, at least for the one with the 2000mAh AA cells: the one with smaller 1500mAh 4/5AA cells does not work well, but I think this is because smaller cells just cannot deliver the proper current or accept the rate of charge). The low-power alarm seems correct, estimated runtime seems correct, and the sleep drain is reasonable (not exactly iPad-standard, lol) in that it seems to use about 33% charge being asleep for 24 hours.

I’m lucky to have several hard drives from these machines, so I would try the sleep/wake with another drive. It’s a long shot but if the drive does not respond, the machine seems to wait. Yes, the sleep fix extension that’s part of EMMpathy is to reduce the drain while asleep, 3lectr1cPPC is right.

I traced my power supply fault to a shorted diode, which I couldn’t identify (coloured bands on glass, 1N64 germanium type perhaps but I don’t wish to risk a substitute). I’ve decided to use a 16V supply and will test what happens with a single supply rail.

 

[jmacz]

I'm still having issues with my battery. Last time it was working, the memory was good, Lind was finding no errors. And it was powering my PB540c. The next day, tried again and my battery won't detect. And this time, no matter what I do, it won't detect. (Note I don't have a PRAM battery in there right now).

The battery pack shows 10.4V so it's charged. If I have the battery out and I check the voltage on the two contact points between the positive/negative ones, I am currently seeing around 1.5V on one and 0V on the other. I could have sworn previously (when it was working), with the battery removed, I was seeing around 4V on the one, and 200-500mV on the other.

What's weird is I would think that even without the intelligent stuff working, if the battery has charge, it should power the laptop. But when I place the battery in, the laptop won't start. So maybe something wrong's with 540c itself?

 

[alexGS]

It sounds a bit like the problem I was having when the ribbon was making poor contact to the battery cells (corrosion…) - voltage seemed correct but the measured current was irregular when charging, and then it didn’t detect at all. To fix it, I soldered wires between the battery tabs and the circuit boards.

Then again, it also reminds me of my 520c that wouldn’t run on battery - it was the terminal inside the machine that needed cleaning up. The crystals scraped off revealing a still-gold finger. I hope you’re similarly lucky with yours.

 

[jmacz]

It sounds a bit like the problem I was having when the ribbon was making poor contact to the battery cells (corrosion…) - voltage seemed correct but the measured current was irregular when charging, and then it didn’t detect at all. To fix it, I soldered wires between the battery tabs and the circuit boards.

Ok, I will try this. Thanks.

 

[jmacz]

It sounds a bit like the problem I was having when the ribbon was making poor contact to the battery cells (corrosion…) - voltage seemed correct but the measured current was irregular when charging, and then it didn’t detect at all. To fix it, I soldered wires between the battery tabs and the circuit boards.

Then again, it also reminds me of my 520c that wouldn’t run on battery - it was the terminal inside the machine that needed cleaning up. The crystals scraped off revealing a still-gold finger. I hope you’re similarly lucky with yours.

The contacts inside the laptop were clean, but cleaned them further anyway, used deoxit, etc. That didn't help.

I ran wires straight from the board to the internal laptop contacts and also straight from the board to the battery. That didn't help either.

Something further must be wrong with this board. Already had to replace two components on this thing, but there must be more damage somewhere.

 

[alexGS]

The contacts inside the laptop were clean, but cleaned them further anyway, used deoxit, etc. That didn't help.

I ran wires straight from the board to the internal laptop contacts and also straight from the board to the battery. That didn't help either.

Something further must be wrong with this board. Already had to replace two components on this thing, but there must be more damage somewhere.

Hmmmm... I'm sorry to have wasted your time on those things.

I have a second battery which worked for a while but now my 520 doesn't detect; perhaps I have the same problem as you. Mine is definitely in the battery as my other battery works OK in the same 520.

I noticed fairly early on that inserting a good battery in my 520 does not allow it to start, until it is powered up with the AC adapter and allowed to detect the battery. Then, the 520 can be shut down, the AC adapter removed, and only then will it start off battery. I presumed that was standard behaviour. From this, I guess any fault that prevents the EMM board from communicating will prevent the battery from being used at all.

I suppose it's necessary to get out the 'scope and look for signs of activity. I don't relish such tasks, as I don't know what I'm looking for, but I imagine with your skill of replacing the parameter memory, you're more clued up than I am

 

[3lectr1cPPC]

I noticed fairly early on that inserting a good battery in my 520 does not allow it to start, until it is powered up with the AC adapter and allowed to detect the battery. Then, the 520 can be shut down, the AC adapter removed, and only then will it start off battery. I presumed that was standard behaviour. From this, I guess any fault that prevents the EMM board from communicating will prevent the battery from being used at all.

This is typical behavior in most laptops from this era if the CMOS/PRAM battery is dead. Have you replaced it in yours?

 

[jmacz]

Hmmmm... I'm sorry to have wasted your time on those things.

Nah, it's all good. Helps to try everything.

This is typical behavior in most laptops from this era if the CMOS/PRAM battery is dead. Have you replaced it in yours?

Yup, I have fresh PRAM batteries installed (it's two coin batteries in series). These are the rechargeable kind, same spec as the originals.

Need to go back to debugging the board a bit more.

 

[alexGS]

This is typical behavior in most laptops from this era if the CMOS/PRAM battery is dead. Have you replaced it in yours?

Ah, I have not, thanks
The PRAM battery actually seems to have come back to life in my 540c, I should test the battery behaviour in that. Someone noted the PRAM battery charges once the main battery is charged, so I’m giving the other a little time as well. I might also try a bench power supply to charge the lithium vanadium pentoxide cells very gently. Panasonic say to use 3.4V fixed-voltage charging. Maybe this type has a longer life than other lithium rechargeable cells.

 

[jmacz]

I spent time analyzing the EMM board some more today and found what looks to be a short. A few capacitors and diodes were buzzing on both ends and it looks like something got shorted to ground. I was measuring a 12 ohm resistance between one part of the board (which shouldn't be grounded) and ground. I started taking off these capacitors/diodes one at a time but found all of them were fine and the short was elsewhere.. the short was present even with those components off the board.

Unfortunately, finally traced the short to the EMM chip which is proprietary and cannot be replaced. I was measuring the same 12 ohms between the chip's ground pin and another pin. I lifted the leg of this pin off the board and the short goes away.

At this point, not much I can do as the chip can't be replaced. I guess I'll save this board in case I need parts off of it. But at this point, I'm looking for another battery.

 

[mdeverhart]

I was measuring the same 12 ohms between the chip's ground pin and another pin.

I guess I wouldn’t write it off until it’s proven that 12 ohms is too low for that part of the circuit. It seems like not much is known about the EMM. I agree, 12 ohms would be too low for a purely digital circuit, but I’ve found that power/analog circuits are less predictable. For example, the output of a switching regulator can have a DC resistance that is of a similar magnitude, but is actually totally fine and expected.

I guess I’d hang onto this battery and try to compare it to another (ideally a known good battery) before concluding that 12 ohms indicated a short.

 

[jmacz]

I guess I wouldn’t write it off until it’s proven that 12 ohms is too low for that part of the circuit. It seems like not much is known about the EMM. I agree, 12 ohms would be too low for a purely digital circuit, but I’ve found that power/analog circuits are less predictable. For example, the output of a switching regulator can have a DC resistance that is of a similar magnitude, but is actually totally fine and expected.

I guess I’d hang onto this battery and try to compare it to another (ideally a known good battery) before concluding that 12 ohms indicated a short.

Yeah, was hoping to procure another battery and compare the two. Things were working up until about a week ago when the battery stopped detecting. Previous to that, I was seeing the two inner connectors fluctuating around 3-4 volts on one and 0.5-1 volts on the other when inside the battery bay, and around those same numbers even when the battery was removed from the laptop. Now it's stuck at 1.5 volts on one and 0 on the other and it's undetected by the laptop. I had checked a couple of those caps previously and I don't recall them buzzing on either end. Anyhow, hopefully will find a battery at some point and compare them.

 

[3lectr1cPPC]

LMK which pins it is on the chip and I can test with my known good EMMs. I can do any tests you need as long as they don’t actually require battery cells hooked up.
Both mine passed EMMpathy before taking them apart, but didn’t hold enough voltage to actually run the computer.

 

[jmacz]

LMK which pins it is on the chip and I can test with my known good EMMs. I can do any tests you need as long as they don’t actually require battery cells hooked up.
Both mine passed EMMpathy before taking them apart, but didn’t hold enough voltage to actually run the computer.

Cool, thanks. The board can be tested completely standalone with no battery cells or connections to the laptop.

If you could try the following for me, that would be great!

• Resistance between pin 14 and 28 - I'm getting 12 ohms.
• Resistance between pin 14 and the ground pad - should be near 0 ohms.
• Resistance between the two ends of the capacitor circled in yellow - I'm getting 12 ohms between them and it's buzzing when in continuity mode.
• Resistance between pin 28 and the top side of the capacitor - should be near 0 ohms as they are connected.
• Resistance between pin 14 and the bottom side of the capacitor - should be near 0 ohms as they are connected.

Thanks!

 

[3lectr1cPPC]

Will test tomorrow!

 

[jmacz]

Will test tomorrow!

Forgot to add the picture; just added it above.