Macintosh Portable Troubleshooting

[Mastergeko4]

I recently bought a Macintosh Portable on eBay. When buying, I was aware of a few common issues it would have. Caps, and the fact it uses a led acid battery and won’t run without one. Purchased a lead acid battery off eBay with the correct specs when buying the portable. (6v 4.5Amp) I know a good amount of vintage Macs and have a pretty large collection but I’ve never had any prior experience to the portable. I decided I may as well give it a shot. With the new battery installed, the portable takes 5-10 minutes until it’ll power up at all. It also won’t power up with the HD plugged in. The screen itself has a weird refresh issue with horizontal lines going from the top to bottom but it does boot to a flashing folder but sometimes a sad Mac with varying error codes. (I’ll put all the attachments below) I’ve also tried booting from floppy but it either gives me a sad Mac or it freaks out. It barely even attempts to read the disk. I washed the board with soapy water and it increased the chances of the computer powering up but otherwise no difference. I did check the board visually and other than some minor leakage, there’s this voltage regulator (or what I’ve been told) at Q16 that looks burnt/crispy and smells like burning electronics when powered off. There’s another nearby that looks normal so this could be the issue to my problem. These symptoms lead me to believe the board having a power issue. I’ve already tested the charger and it reads 7.3v and the connector is fine so it’s nothing there. Battery is fine too. At the moment I might be looking at replacing the caps and that resistor if I can find one but I wanted to see what you guys think. Thanks! 
I’ll post more pics and videos if needed.






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[techknight]

Did you recap the unit? if not your wasting your time. 

you need to recap and clean the PCB before you can do any troubleshooting. 

 

[maceffects]

Did you recap the unit? if not your wasting your time. 

you need to recap and clean the PCB before you can do any troubleshooting. 

100%, caps and their leakage cause all kinds of strange and difficult to diagnose issues.  The Macintosh Portable is one of the most temperamental Macs.  Others might include the Quadra 840av, IIfx, SE/30, etc. 

 

[Mastergeko4]

100%, caps and their leakage cause all kinds of strange and difficult to diagnose issues.  The Macintosh Portable is one of the most temperamental Macs.  Others might include the Quadra 840av, IIfx, SE/30, etc. 

As I stated before, I’ve already cleaned the entire motherboard and I plan on recapping it. I just wanted to see if anyone had any other advice.

(whoops wrong post to reply to)

 

[LaPorta]

I'll echo the cap recommendation. Techknight was instrumental in helping me get my Portable up and running a few years ago. Not just a cap replacement, but also removing some crud from some of the video circuitry helped clear up a vertical line issue I was having. I also will warn you that not just the voltage and amps matter, but also the rate at which it is able to discharge. I had an "in spec" battery that failed to power mine because the peak amps were too few. Getting an exact replacement from the original manufacturer cleared that up.

 

[Mastergeko4]

I'll echo the cap recommendation. Techknight was instrumental in helping me get my Portable up and running a few years ago. Not just a cap replacement, but also removing some crud from some of the video circuitry helped clear up a vertical line issue I was having. I also will warn you that not just the voltage and amps matter, but also the rate at which it is able to discharge. I had an "in spec" battery that failed to power mine because the peak amps were too few. Getting an exact replacement from the original manufacturer cleared that up.

Thank you! That’ll be very helpful. I was told my battery is in spec by a few others that are helping me troubleshoot this thing. The battery is a 6v led acid at 4.5amp. I might get a different one if it’s needed. I think the first thing I’ll be doing though is a recap as it seems like the likely suspect but if not, I’ll report back here in a week or two when the job has been done. Btw, where would I find the video circuitry? 
Thanks!

 

[Stephen_Usher]

I'll repeat what everyone else has said, replace the capacitors. On the Portable they are guaranteed to be bad and cause all sorts of problems. It's possible that they killed the voltage regulator at some point, though I've had more issues with Q10, Q11 and Q12.

 

[LaPorta]

Just incase the battery proves to be problematic, this is the direct replacement that I used. Same specs, manufacturer, and three cells:

https://www.batteriesplus.com/battery/sla-sealed-lead-acid/6/hawk0809=0012

 

[Mastergeko4]

Just incase the battery proves to be problematic, this is the direct replacement that I used. Same specs, manufacturer, and three cells:

https://www.batteriesplus.com/battery/sla-sealed-lead-acid/6/hawk0809=0012

Thank you! I’ll make sure to try this out if the battery that I’m using doesn’t work.

 

[Mastergeko4]

I'll repeat what everyone else has said, replace the capacitors. On the Portable they are guaranteed to be bad and cause all sorts of problems. It's possible that they killed the voltage regulator at some point, though I've had more issues with Q10, Q11 and Q12.

Recapping is next on the list however I’ve heard that caps probably won’t be the only issue. I’ll update you guys later once I’ve finished the recap if I keep having issues. 

 

[LaPorta]

Please do keep us informed!

 

[Mastergeko4]

Please do keep us informed!

I will. The caps for the board have just been ordered and should arrive by Monday. Chances are I’ll finish up by either Tuesday or Wednesday.

 

[Mastergeko4]

UPDATE: I’ve completed the recap and it seemed to fix the flickering screen issue. I did get some random sad Macs until I was able to get it to the boot menu. I was actually able to boot it from floppy but when booted, it would either freeze or it would freeze/restart at the welcome to Mac screen. I’ll add some pictures to this post. It won’t turn on with just the battery, it must have both the power adapter and battery plugged in. Let me know what you guys think. 
 

 

[LaPorta]

Tech knight is the real authority, but it sounds to me like the battery can’t discharge fast enough to power the unit.

 

[Mastergeko4]

Tech knight is the real authority, but it sounds to me like the battery can’t discharge fast enough to power the unit.

Interesting. Let's see what he has to say about this. I may look into getting a different battery. 

 

[Mastergeko4]

Did you recap the unit? if not your wasting your time. 

you need to recap and clean the PCB before you can do any troubleshooting. 

I've just finished the recap and the computer seems to sad mac rarely now. The computer won't power up on just the battery and when plugging in the hard drive, the computer screen will flicker with the violent unnatural clicks. I'm able to boot it from floppy but it either restarts during the boot process or it will freeze. I was able to get it to the desktop but the farthest I got was a frozen screen. Any ideas on the HD? I assume the boot disk is acting up because the floppy needs cleaning.  

 

[LaPorta]

With the extra symptoms you described, I would definitely suspect the battery. I had similar symptoms with the original battery I had. I'd purchase one of the ones that I posted the link to above.

 

[Mastergeko4]

With the extra symptoms you described, I would definitely suspect the battery. I had similar symptoms with the original battery I had. I'd purchase one of the ones that I posted the link to above.

Alright, I guess I’ll also be buying one of those batteries then. 

 

[LaPorta]

Techknight should also weigh in as you stated. He also knows the ins and outs of these, probably better than anyone else here.