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#1 2014-07-13 00:03:39

techknight
Member
Registered: 2014-05-22
Posts: 449

Mac Portable motherboard repairs

What a nightmare.....

Finally started getting around to working on mac portable motherboards, they are starting to pile up here.

I had 3 off the top of the stack from haplain, after all day today, I managed to get 1 working and another one partly working.

First one had a bunch of dark splotches in the traces. The dark splotches mean the copper is totally eroded away. I lifted the solder mask and nothing was there. Gone.

Also, using a bright flashlight from the backside of the motherboard, you can see the annular rings around the vias, in the inner ground plane. This is nice because the light shines through around the via. I found several vias where the copper has vaporized, allowing light through. So after several patches later, the portable came to life. It had no sound at first, then I found again another dark patch in one of the fat traces running near the apple sound chips. lifting it reveled no copper. so i patched that up, and sound came back. Whew....

the other 2 not so much.

the 2nd one had a couple of bad/open traces from dark eroded copper. One even under the bourns network filter near the op-amp IC. Fixed that, and also the 5V mosfet regulator transistor was weak. it appeared to have been very hot at one time, it was causing alot of studdering, random resets, sometimes not coming up at all. After replacing that with a brand new IRF9Z30, it worked fine. But it reads the battery as full and wont charge. Checked all the traces, it appears that the PMU IC itself has an ADC that reads the battery voltage during runtime against a reference. These 2 voltages are spot-on. This means the PMU IC itself is bad. Eh.... Anyway.

the 3rd board was recapped by uniserver for haplain, it had corrosion around the RAM ICs thesmelves. It did power on, but with a 00000010
0000CD37 i think it was, I cant remember. I found only 1 bad trace on that one. Fixed it, and i removed the RAM to clean it up, found another open trace underneath the RAM IC. Fixed that and remounted the IC. Doing this made it worse, no more chime, no more sad mac, no more anything. I checked everything and came up empty.

I did some probing with a scope, and seen a little bit of activity on the system bus. But from a glance of the bus activity, it appears that its stuck in a tight loop. God only knows why, so i looked at the sad mac code and came up with an unable to read PMU. if i interpreted it correctly. Which i would suspect the VIA over the PMU, as the VIA is what reads/writes the PMU IC. Now, if the VIA had died i guess it would explain the no-post now. But, then again, i dont think a bad VIA would stop the system from at least showing a sad-mac. But maybe, maybe not. No idea. at a loss, all voltages stable.

Thats my rant for the day. :-)

Here is some pictures of the projects
20140712_131502.jpg
20140712_132923.jpg
20140712_132928.jpg
20140712_132936.jpg
20140712_142304.jpg

Last edited by techknight (2014-07-13 01:02:07)

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#2 2014-07-13 00:24:35

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

Would be nice if I had a custom written ROM to go into the ROM slot, that would probe the bus and its peripherals, attempt to initialize and communicate with every piece of on-board hardware, and then halt/pulse a code to indicate which part failed.

Last edited by techknight (2014-07-13 00:25:37)

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#3 2014-07-13 01:38:24

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 955
Website

Re: Mac Portable motherboard repairs

Yeah, that would be kind of cool... You know Hap has a Custom Rom Card, its Labeled Espirit smile  pretty much a rom card with a couple IC's on there.

Yeah looks like each board has issues in different ways.  i suppose after a # of fixes you could make a little table ... kind of like how they did in the Dead Mac Scrolls.

- if you have no sound
Check here and here and here   etc..

- if you are not charging
here and here

- if you have no back light
here

- if you have all black screen and no bong
here

- if you have bong, and scsi and everything but sad mac
then check ram.
here  smile


Any ways... looks like each board seems to have its own set of surprises buddy.
Since you are like the only one in the world that is fixing these right now .. no pressure smile
But you don't call your self TheTechknight for nothin!

Next up ... 840av's    Woah...      :-)
just kidding forget about the 840av and focus on the Portable... your efforts are massively appreciated.
and hopefully decently compensated...

Last edited by uniserver (2014-07-13 01:40:12)


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#4 2014-07-13 03:29:00

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

Well, here is the thing. the good ol cause/symptom/repair charts/tables wont work here. because each board has its own set of damage related to the failures.

HOWEVER...... there is a however....

The cause of the failure is capacitor leakage! obviously. the damage is occurring around the capacitor farms. the capacitor farm near the audio circuit, and each end where the keyboard/mouse plugs into. These are where the damage has been concentrated at.

This is the best I can do. The rest is physical eye pain labor finding the broken connections.

With todays experiences and the guide to the macintosh family hardware, I pretty much figured how this circuit works. the PMU chip is the brain of the entire process. Everything else is pretty much a souped up Mac SE.

Last edited by techknight (2014-07-13 03:30:26)

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#5 2014-07-13 03:47:35

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

I dont know any 68K assembly or I would write it myself. Given enough guides and manuals out there, plus emulator sources I am sure I could init and test hardware/peripherals on the logic board.

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#6 2014-07-13 20:25:28

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 955
Website

Re: Mac Portable motherboard repairs

on that ram fix there,   what caused that one, didn't see any caps around that bad boy.    maybe take a picture of the audio circuit issue you fixed?
thanks


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#7 2014-07-13 21:45:18

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

the main battery leaked. thats likely what caused it. Or the 9V battery leaked. Anyway, that board appears to be junk anyway. the GLU failed I am pretty certain.

I started hammering back on the battery level issue board today, I found another open trace going to the capacitor. That didnt fix the issue, it actually made it worse. the meter will fall, then rapidly climb back and sometimes shut off.

I am coming to the conclusion that some of the cap juice has leaked in between layers, forming parasitic capacitances/resistances and its causing the op-amp to bounce all over the place. I scoped it and confirmed that suspicion. my feedback voltages are bouncing all over the place. swapping the bourns/op-amp makes no difference.

Anyway, So i decided to get onto uniservers boards. the backlit board was sadmac failed PMU. Turns out one of the connections were open. Jumped it and it fired up. However its freezing just before it gets to the desktop. the pattern draws, and the menubar draws, but there is no text on the desktop, no icons, and no menubar text. So, not sure what peice of hardware the system software is attempting to initialize before the desktop, but its locking up at that point. Bah..... Anyway....

So the non-backlit board, appears to have the identical issue as haplains. No bong, no boot. data/address bus appears in a tight loop or not remapping ROM/RAM addressing. same identical failure. probably the same issue, bad GLU.

Another idea is to swap the good logic chips from the board that has battery issues, over to the board that has correct battery meter operation but no boot operation. That would be way more time than I want to invest into the project, but I havent decided.

Last edited by techknight (2014-07-13 21:53:53)

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#8 2014-07-14 02:19:51

cc333
Member
From: North S.F. Bay Area, CA
Registered: 2014-05-23
Posts: 562

Re: Mac Portable motherboard repairs

I have a backlit M5126 board that's useless to me in it's current form. Would you consider working on it?

It's either that, or find a replacement. Replacement is not preferred because of a) cost and b) rarity.

Thanks,

c


Main Macs: Early '09 Mac Pro, Mid '12 MacBook Pro 13"
Secondary Macs: Early '08 Mac Pro, Mid '12 MacBook Pro 15"
Playthings: Mac SE/30, 3.0 GHz Mavericks-based HackServe, Many others....
Desired: Lisa, Kanga PowerBook G3, Apple IIc, Apple II, Spare parts, etc.

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#9 2014-07-14 02:25:48

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

whats wrong with it?

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#10 2014-07-14 03:09:20

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 955
Website

Re: Mac Portable motherboard repairs

i am very glad you are doing this techkinght, thanks.. and all of what i sent you is yours.   if you end up with stuff that is repaired but you would like to be sold just tell me... and i will try to find a buyer for you .. and give them your paypal,,  drop ship like deal...  ITs the least i can do for you and your hard work.


#I Re-Cap √Mac √NeTX √Amiga Boards - A/B - PSU# (MacCaps.com)  Modern SCSI HD's - For Old Macs - Pre Cfg'd - 10k RPM! 73gb!! $50 + free shipping  -- Mac 128K Re-Ram kits (16 Chips) $35 + shipping, Floppy Issues?-> Bourns Filter Solution 128k - SE/30, $16 + shipping

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#11 2014-07-14 16:35:03

cc333
Member
From: North S.F. Bay Area, CA
Registered: 2014-05-23
Posts: 562

Re: Mac Portable motherboard repairs

Well, it was from haplain (I asked for the cheapest, and didn't care if it worked or not), and apparently, there was a small chip on one of the corners which caused it to get stuck in a reset loop where it would only bong once per second or so.

I tried resoldering a few capacitors, and it got worse. Now it just sits there, and when I power it on, all I hear is a faint pop from the speaker and some very faint hiss (probably meaning the audio amplifier is working), and nothing else. It is completely dead for all intents and purposes.

Maybe with Uniserver's decision to let you keep the ones you've been working on, I could trade a working backlit board for my nonworking one?

c


Main Macs: Early '09 Mac Pro, Mid '12 MacBook Pro 13"
Secondary Macs: Early '08 Mac Pro, Mid '12 MacBook Pro 15"
Playthings: Mac SE/30, 3.0 GHz Mavericks-based HackServe, Many others....
Desired: Lisa, Kanga PowerBook G3, Apple IIc, Apple II, Spare parts, etc.

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#12 2014-07-14 16:54:33

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

I would have to see the board.

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#13 2014-07-14 16:55:29

cc333
Member
From: North S.F. Bay Area, CA
Registered: 2014-05-23
Posts: 562

Re: Mac Portable motherboard repairs

Would you like me to send it over?

c


Main Macs: Early '09 Mac Pro, Mid '12 MacBook Pro 13"
Secondary Macs: Early '08 Mac Pro, Mid '12 MacBook Pro 15"
Playthings: Mac SE/30, 3.0 GHz Mavericks-based HackServe, Many others....
Desired: Lisa, Kanga PowerBook G3, Apple IIc, Apple II, Spare parts, etc.

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#14 2014-07-14 17:14:55

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

Yea but youll need my new address.

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#15 2014-07-14 17:16:31

cc333
Member
From: North S.F. Bay Area, CA
Registered: 2014-05-23
Posts: 562

Re: Mac Portable motherboard repairs

OK, PM me with your address and I'll send it over!!

c


Main Macs: Early '09 Mac Pro, Mid '12 MacBook Pro 13"
Secondary Macs: Early '08 Mac Pro, Mid '12 MacBook Pro 15"
Playthings: Mac SE/30, 3.0 GHz Mavericks-based HackServe, Many others....
Desired: Lisa, Kanga PowerBook G3, Apple IIc, Apple II, Spare parts, etc.

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#16 2014-07-14 19:35:13

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

I dont see a pm box anymore...

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#17 2014-07-14 21:45:51

mcdermd
Member
From: Corvallis, OR
Registered: 2014-05-12
Posts: 950
Website

Re: Mac Portable motherboard repairs

thinkclassic.org has never supported any Private Messaging. There is an option to email the other member directly but no PMs.


Daily Drivers: 27" iMac 2.8 GHz Quad-Core i7 (Late 2009), 21.5" iMac 2.7GHz Quad-Core i5 (Late 2013), 11" Macbook Air 1.6 GHz i5 (Mid-2011)
See the restored heroes here.

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#18 2014-07-15 00:00:39

cc333
Member
From: North S.F. Bay Area, CA
Registered: 2014-05-23
Posts: 562

Re: Mac Portable motherboard repairs

Yes, what mcdermd said.

Anyway, I'll get it boxed up and ready to go.

You can always reach me via PM at 68kMLA as well, if you wish.

c


Main Macs: Early '09 Mac Pro, Mid '12 MacBook Pro 13"
Secondary Macs: Early '08 Mac Pro, Mid '12 MacBook Pro 15"
Playthings: Mac SE/30, 3.0 GHz Mavericks-based HackServe, Many others....
Desired: Lisa, Kanga PowerBook G3, Apple IIc, Apple II, Spare parts, etc.

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#19 2014-07-17 23:46:23

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

These machines are really starting to get on my nerves, lol....

Anyway, I decided to get back to them again today, and yesterday. the corroded/no post board I replaced every single IC. from the good board that has battery monitoring issues.

1 chip at a time, All of them. GLU, CPU, etc... I left the SCSI, SWIM, and SCC behind. I didnt change those. But I changed everything else, all the RAM controllers, RAM, ROM, etc...

The dead board still stayed dead, and the good board still worked fine. So that ruled out all the ICs.

I cant find any open vias or traces that I can see, but there is obviously one gone somewhere. Uniservers non-backlit board has the exact same problem, and shows the very same type of waveforms on the bus. so whatever is causing this is common between the two boards.

So i gave up, and went back to the good one with batt issues. So now that every chip was basically swapped and the problems persisted, I decided to take a closer look on how it was acting. the ADC would start off correct then it would quickly ramp up to 5.7V. almost 6V if you let it. thats dangerous to the PMU.

Come to find out, the 47Uf tant cap that someone put in there was internally leaky! and bad.

Removed it, and stuck another cap on. Problem gone. So now that board is working perfectly and reading the battery voltage correctly.

Thank god.

Still dont solve my problem with the apparent braindead boards.

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#20 2014-07-18 01:19:59

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

Thinking about building a test card to probe the bus and find out where the problem is.

There are multiple ways I can do it. 1 way is use a high speed CPU attached to the address bus, and latching in addresses to find out where its hanging up in ROM.

2nd way is design a little bit of 68K code to run on the real machine to probe peripherals and ROM/RAM. Then attach a latch with LEDs to an unused address space, as each thing pases, one light lights. etc...

3rd thing, is just disable the 68K CPU, and use my own MCU to take control of the bus and prob everything without the machine running. But this can be flawed in the event that the bus might be ok at the PDS, but broken at the processor itself. But I dont know enough about the 68K bus states, and asynchronous/synchronous timing, the datasheets just make it much more confusing. Need a doctorate in computer science to understand it.

Last edited by techknight (2014-07-18 01:27:50)

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#21 2014-07-18 02:35:59

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 955
Website

Re: Mac Portable motherboard repairs

lol

having issue posting youtube links... 


Just wanted to say your my hero smile  did the tantalum look bad?

Last edited by uniserver (2014-07-18 02:41:27)


#I Re-Cap √Mac √NeTX √Amiga Boards - A/B - PSU# (MacCaps.com)  Modern SCSI HD's - For Old Macs - Pre Cfg'd - 10k RPM! 73gb!! $50 + free shipping  -- Mac 128K Re-Ram kits (16 Chips) $35 + shipping, Floppy Issues?-> Bourns Filter Solution 128k - SE/30, $16 + shipping

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#22 2014-07-19 00:56:00

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

Nope, but it was leaky internally. Not leaky as in fluid leakage, Leaky as in electrical resistance.

So i stole a ceramic from a board you recapped, and tossed it in its place. Problem solved, now the battery meter is stable and operating correctly.

Anyway, Further progress update:

Trying to get to the bottom of the issues of the no-post.

I decided to probe 3 signal lines in the processor. /BERR, (bus error), /HALT, and /RESET.

On a good board, all 3 lines are high, and no triggering. As expected.

Now... the bad board: It seems that BERR signal stays high mostly, but there are 3 short negative-going pulses. then a pause for a bit, and 3 more short pulses. The pulse is probably the width of a single bus cycle so of course they are short.

That means for some reason, we keep getting a bus error thrown at us. So I decided to probe the /HALT line. We are getting a consistant negative-going pulse train here. As expected, as if the bus is taking longer than expected, it will assert /HALT to insert wait states in the bus cycle. But it never completes so it throws a bus error.

Then, the /RESET signal which should be high. But nope, again the signal here is identical to /HALT. my assumption? the cpu is throwing a bus error, being halted and is reset. So it starts from the beginning again at which point it fails. Basically, a vicious cycle. Ugh... So that makes me think it cant even decode ROM.

Which brings me to another point: I decided to do some probing on the logic board, the RAM outputs are buffered, and are tri-stated by the glue logic, throgh a 74AS244  near the processor, and ironically right below the ASC chip which is in the target zone for cap goo. So i decided to meter those, and didnt find any broken connections but I did decided to trace out the circuit and draw a schematic from it, which i didnt find any opens. but i may have missed a few intersects to other ICs. But youll get the basic idea:

20140718_185558.jpg

So back to what I was saying: I decided to probe the tri-state control line to the RAM buffers, and its high. Never pulses low at any time, so the bus-error is being thrown way before the system even attempts to access RAM. So ram never gets touched, and therefore can be automatically ruled out. I checked all data and address lines to and from the ROM/RAM and CPU, they are all good. There is 2 more buffer chips that buffer the address lines to the ROM/RAM. These buffers tri-state input is grounded so the buffers are just drivers. they arnt ever switched in/out.

Thats where I stand at this point. Next thing is if someone would be nice enough to donate a logic analyzer to the cause, I would appreciate it GREATLY! because I can set it up to trigger off the bus-error raised event, and figure out where the address is at the time of the error. this will tell me EXACTLY what part of the bus is being blown away.

Last edited by techknight (2014-07-19 00:56:15)

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#23 2014-07-19 02:48:49

uniserver
Member
From: Sf, Mi
Registered: 2014-05-15
Posts: 955
Website

Re: Mac Portable motherboard repairs

wow sweet diagram man...   Assume that someone ran the board with out a Lead Acid battery installed... they popped in a 2.0a or 3.0a  powerbook adaptor... and ran the machine even with bad leaking caps, witch made it worse...    So its best to understand how the user fried it in the first place....    because i think that is a very common scenario....  Very Unfortunately.


#I Re-Cap √Mac √NeTX √Amiga Boards - A/B - PSU# (MacCaps.com)  Modern SCSI HD's - For Old Macs - Pre Cfg'd - 10k RPM! 73gb!! $50 + free shipping  -- Mac 128K Re-Ram kits (16 Chips) $35 + shipping, Floppy Issues?-> Bourns Filter Solution 128k - SE/30, $16 + shipping

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#24 2014-07-19 02:55:32

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

Various pictures of the project:

some of these may not make any sense, as they were just for my own reference. But I did get trace-shots underneath the removed ICs. For future reference.

20140713_102726.jpg
20140713_102739.jpg
20140713_102754.jpg


Pseudo RAM/DRAM to SRAM conversion logic, plus ROM and data/address buffer ICs.
20140717_084425.jpg
20140717_084553.jpg
20140717_084558.jpg


20140717_122505.jpg
20140717_122524.jpg
20140717_122539.jpg
20140717_122544.jpg
20140717_122553.jpg
20140717_122604.jpg
20140717_151313.jpg


Non-Backlit board shots.
20140718_174331.jpg
20140718_174336.jpg

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#25 2014-07-21 03:15:51

techknight
Member
Registered: 2014-05-22
Posts: 449

Re: Mac Portable motherboard repairs

I assume the silence is amazement? or maybe I am just boring you all. Im getting worried. lol.

Anyway, here is another picture of my depiction of whats happening:

ground%20zero.jpg

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