2400c No-Start after PRAM removal

[LCARS]

I see I'm jumping on the 2400c thread bandwagon as of late. I was very happy to read about how to keep these happy. To that end, I removed the PRAM battery tonight and ran into a problem.

I used a great YouTube video and the Apple Service Source manual for the disassembly instructions. Before this, the machine worked more-or-less fine. Sometimes it would boot without the backlight and sometimes it would not wake from sleep (or jump to boot up after plugging in)...but it worked. After removed the PRAM battery (no leaks) the machine will not boot.

The speakers clip when plugging into AC, but no boot from the on/off or reset. I'm not experienced at taking apart portables; does this scenario seem like a re-assembly error? Or is it unhappy without the (dead) battery? I could not remove the white connector from the board. The +/- wires practically fell out so I left the white connector on the board. Might that be the problem?

Any insight is appreciated : ) I've uploaded the Service Source manual in case anyone might need it.

View attachment powerbook_2400c.pdf

 

[Byrd]

My experience having recently pulled apart 3 x 2400c is the CPU daughter card and power board need to be cleaned well before reassembly.  I'd take it apart and have another look; you don't need a good PRAM battery for it to boot.

The fragility of the PRAM connector might be due to corrosion; two out of three 2400c looked at the battery itself was fine but the connector to the motherboard had corroded.  I'd certainly check this over again too.

 

[LCARS]

Hi Byrd. Thank you for your reply. Yes indeed, the leads that came out are corroded. It's no wonder that it was acting up prior to.

By cleaning do you mean ensuring that the connections are clean and properly seated? While I'm asking questions, I forgot to ask one earlier: Does the screen flex cable need to be rewound when re-assembling? Mine seems to not fit back into the hinge shell very well.

 

[Byrd]

If you're dismantling it down again, spraying the CPU daughter card and power board contacts with IPA/electronic cleaning solvent can assist.  

The screen flex cable is loose around that part of the hinge, just make sure it's tucked back in and out of harm's way when reassembling.

 

[glay78]

I see I'm jumping on the 2400c thread bandwagon as of late. I was very happy to read about how to keep these happy. To that end, I removed the PRAM battery tonight and ran into a problem.

I used a great YouTube video and the Apple Service Source manual for the disassembly instructions. Before this, the machine worked more-or-less fine. Sometimes it would boot without the backlight and sometimes it would not wake from sleep (or jump to boot up after plugging in)...but it worked. After removed the PRAM battery (no leaks) the machine will not boot.

The speakers clip when plugging into AC, but no boot from the on/off or reset. I'm not experienced at taking apart portables; does this scenario seem like a re-assembly error? Or is it unhappy without the (dead) battery? I could not remove the white connector from the board. The +/- wires practically fell out so I left the white connector on the board. Might that be the problem?

Any insight is appreciated : ) I've uploaded the Service Source manual in case anyone might need it.

View attachment 38419

Hi have you got it to work? My 2400c also have the same problem. First A/C on has a speaker clips sound. Nothing happens, off and on the A/C will show green light of death. Nothing happens too. I tried holding the reset but nothing happens too.

 

[LCARS]

I'm sorry to hear that you're having the same problem. I haven't tried again yet but I plan to this weekend. I'm going to take it apart again and double check the connections.

 

[Byrd]

Hi have you got it to work? My 2400c also have the same problem. First A/C on has a speaker clips sound. Nothing happens, off and on the A/C will show green light of death. Nothing happens too. I tried holding the reset but nothing happens too.

Hi glay78,

Was it working fine "the day before"?  If a new aquisition I'd suspect it the GLOD issue is more related to SMT fuses on the motherboard that can blow - it's a very sensitive machine in this regard.  Also check your Power adapter voltages - I repaired a 2400c, then quickly blew 2 fuses when the original Apple power brick I was using was out of spec.

JB

 

[glay78]

Hi glay78,

Was it working fine "the day before"?  If a new aquisition I'd suspect it the GLOD issue is more related to SMT fuses on the motherboard that can blow - it's a very sensitive machine in this regard.  Also check your Power adapter voltages - I repaired a 2400c, then quickly blew 2 fuses when the original Apple power brick I was using was out of spec.

JB

Oh ok let me check power adapter voltage in a while. No it’s not newly bought. It’s taken out from storage stored long ago.
 

which are the fuses that blows? I can check the board too.

 

[LCARS]

Sigh....After taking the board out, checking the connections, and reassembling, still no boot. If I push in the functional battery or the plug it into AC, the speaker pops but that's it. The PMU reset button is very flimsy. After several attempts at holding it in for 10+ seconds to reset the power manager, nothing. I even plugged in an ADB keyboard to see if it would power on that way.

I've included two pictures. You can see how corroded the PRAM connection became. Could that be the problem? I don't know what a blown board fuse looks like but does the top of the board look OK?

One thing I should note: I have (temporarily) misplaced the second screw behind the main battery. I swapped the remaining one to both sides and that didn't make any difference.

 

[LCARS]

Additional note: Plugged in, the speaker emits a faint hissing sound.

 

[Franklinstein]

The blue crystalline material and the exposed yellowy plastic of the inner frame near where the battery used to live suggests you've had more of a leak than you suspect. It doesn't look too severe but there may still be a little bit of contamination somewhere.

You may have jarred the processor card loose. I recommend removing it entirely (should be 4 screws) and reseating it, pressing very firmly along the flat back area above the twin connectors. Also let the computer sit for a day or three without power and/or plug it in and repeatedly hold down the reset button for 60 seconds until you either get a chime or you lose patience.

 

[Byrd]

I've come across the PRAM connector corrosion in all 2400c recently taken apart - sample size ~ 5.  I'm also with Mr. Franklinstein that the CPU daughter card connector is weak and needs cleaning with electronic solvent spray before reseating it firmly on all corners.

You can clean the corrosion using white vinegar and a soft toothbrush, then wipe all areas down with IPA.

See this thread on location of fuses and checking their continuity - you want to check the ~ 7 odd little clear SMT fuses, not the larger ceramic ones.

 

[LCARS]

Thank you Franklinstein & Byrd. That is a thorough documentation. Sigh, it looks like another tear down. At this point I should be used to it. I'll give the CPU daughter card a reseat tomorrow and check the fuses. The 7 SMT fuses to be checked are in a single location? Or are there only 7 in total?

 

[Byrd]

Yes I know your pain @LCARS; taking apart the 2400c isn't much fun although probably no worse than other laptops.  I received 4 x 2400c recently, all got working to a point after some laborious parts shuffling but the lesser machines had several issues (bad sound, RAM slot not working, issues with precious one and only G3 CPU upgrade I had).

The 7 x SMT fuses are randomly placed at top and bottom of the motherboard; IIRC when I last blew mine from a marginal Apple PSU it took out two on the plantar/bottom side of the board.

 

[LCARS]

Four! That must have taken an entire weekend. Did the G3 upgrade pull through? The tear downs are getting easier, although the continued no-starts are testing my resolve. I took the power & processor boards off. The fuses (to me) look fine. None seemed out of place or clearly blown. I couldn't remove the entire metal shield to the I/O ports but peering underneath, it looked new, dust-free even.

I made a point to reconnect the boards with evenly placed pressure and visually checked with my flashlight. All to no avail. I've been doing the PMU reset technique but no happiness there, either. I feel the need to put it away for a while and try again later. However....I do have a second 2400c that does work. It often forgets to power on the backlight until it gets a PMY reset every now and then. I'd like to remove it's PRAM battery and stick in a 7200RPM drive, but I'm clearly worried it will become another paperweight.

Forgive the not-so-great pictures; I'm losing my energy on this project. Having left it plugged in for hours (sans battery), the bottom is warm. It feels like it does when its been in use for a bit. It's curious. Unless there's a blown fuse that I didn't notice or didn't check, this is very strange. When passion strikes again, I'll pull the RAM and try booting it in various states of undress.

 

[Byrd]

Four! That must have taken an entire weekend. Did the G3 upgrade pull through? The tear downs are getting easier, although the continued no-starts are testing my resolve. I took the power & processor boards off. The fuses (to me) look fine. None seemed out of place or clearly blown. I couldn't remove the entire metal shield to the I/O ports but peering underneath, it looked new, dust-free even.

Yes, four of the &#%$@!  Cleared the benches and made it almost look like an assembly line.  The thing was though none worked until I did the parts shuffle and cleaning - so it was kind of rewarding.  I do recall powering them up in various states of disassembly as you've mentioned.  The fuses need to be checked with a continuity meter.  With your working 2400c, I suppose if you can vividly remember how it all comes apart, it might be a good time to pull the good one apart - but give it a week of isolation before going back I reckon!

The G3 upgrade appears marginal - coming up with cache errors and freezing.  Like you I suspected it was a motherboard fault but they all did the same thing with the G3 after a while.  Needs more time spent.

 

[LCARS]

An assembly line sounds like the most efficient method for a batch of them. Ah, I can see how that would be rewarding. Which parts proved to be the magic combo? A digital multi-meter- I should just buy one. This is the first hardware issue I've had in my classic Mac life. Well, save for the Nubus Ethernet card that burst into flames.

You're right- on the one hand I do have working memory of how to disassemble these but I'm definitely jittery about causing this problem again (if it was my fault). It's a shame that the one pre-PDQ PowerBook that doesn't suffer from weak hinges, is such a complicated little thing to diagnose. I have a 550c on the bench right now. Once that's done I'll try again.

Cache errors- that sounds incredibly frustrating. Is it from NuPower?

 

[LCARS]

Update: It booted! However the backlight did not initiate and it doesn't see the RAM card (only reporting the 16MB on the board). I'm going to see if I can cycle is through a few times.

Drat- Selecting restart just sent it back into a no-start situation. The only way to get the chime is to press power as soon as its been plugged in. But it will either continue to boot or it will do nothing.

 

[glay78]

Update: It booted! However the backlight did not initiate and it doesn't see the RAM card (only reporting the 16MB on the board). I'm going to see if I can cycle is through a few times.

Wow nice! What did u do to make it boot?