GOTCHAS when buying a Macintosh Portable?

[JDW]

I am curious what issues people need to be aware of when buying a Macintosh Portable, especially the backlit model (5126).

I realize Portables won't power on without a good battery, but new batteries like this are sold on EBAY. Maybe some of you can share experiences with those.

I also realize it needs to be recapped before one tries to power it on.

But are there other common issues?
For example, I often hear about dark screens on the PowerBook series, but what about the Macintosh Portable display?

What parts easily break or get damaged, especially during shipping?

Many Portables are sold untested because the seller lacks a working battery and/or power adapter. So what are the questions one should ask sellers to avoid trouble post-purchase?

Pricing most likely varies wildly by model and condition, but there are not a large number on EBAY at the moment to properly gauge the "going rate" these days. It's not realistic to just reflect on the good old days when somebody found a Portable sold for $20 in a used goods store. I think most people wanting to buy a Portable would want to know what price range is normal, and what prices are excessive.

I look forward to hearing your thoughts. Thanks!

 

[moldy]

I'll try to share my experience with 3 Portables I own - one backlit (M5126) and two non-backlit (M5120).

For example, I often hear about dark screens on the PowerBook series, but what about the Macintosh Portable display?

This is a rare problem but it occurs. I have one non-backlit portable with a slight tunnel vision problem.
I also have a portable that has a dead line on the LCD so those might pop up as well.

But are there other common issues?

• 9V backup battery might leak and corrode / eat out traces around the memory chip (this can be checked by a seller).
• Hybrid on M5120 (non backlit) is a classic issue that suffers from cap goo. Bad/rotted hybrid can fry the Power Manager chip, which is custom and not easy to get (can be scavenged from another Portable or PB100). I have two @Androda's hybrids already in my M5120s and I would recommend replacing a hybrid by default as the risk of the fried PMGR is just too high. Practically all the horrid stories of Portables being unstable or rebooting or not turning on are IMO caused by the Hybrid problems.
• Sometimes the SWIM chip dies making the Portable reach the "gray screen + cursor" stage, but without a happy mac / blinking floppy. It can be replaced with one from desktop Macs (potentially with a negative effect on the battery life).
• The Conner HDD's seals and head bumpers turn to goo. I was pretty lucky here in Europe with all 3 working, but I clearly see the seal degradation as well and one of them was leaking some weird fluid.
• The caps in the power supply leak as well and might cause the voltage to be unstable. I'd aim to run at recapping it as well before using it.

While this list might sound scary, I can say I was pretty lucky - all 3 portables I own required just: cleaning, recapping (and catching one short which I accidentally caused because of rotten soldermask), recapping the power supplied, recelling the battery, replacing the hybrids on M5120 and were just working.

What parts easily break or get damaged, especially during shipping?

One of my Portables was terribly packed during shipping and still survived, I must say that the original case protects them pretty decently. The cases can still crack though, I saw a few cracked ones on ebay.

It's worth noting that schematics for M5120 are available and very helpful in troubleshooting. While completely different in the power circuit area, they were still very helpful for me to debug the address lines on my M5126.

The going rate in Switzerland (when I monitor the prices somewhat) is around 300-400 CHF (US$350-450).

 

[JDW]

Thank you for the excellent feedback! I now have 2 questions...

1. So the 5126 doesn't have a "Hybrid" and therefore is perhaps a better choice than the 5120 model Portable?

2. What causes the SWIM chip to die? Cap goo?

If prices are that low in Switzerland, I need to acquire one from there! Yikes! Those are the prices Portables used to sell for on EBAY over a decade ago. I strongly considered buying back then, but the machine's stubborn need for the battery was always a big turn off for me. Even so, there's something special about the Portable. It takes a lot of heat in the press for it's large size and heavy weight, but I don't care about that. It was the first Apple Portable, and its active matrix screen was better than the first PowerBooks, except for the 170, which too had an active matrix display. But there's a certain charm about the Portable which the early PowerBooks lack. Maybe I alone think that way, but I can't help it. It's a nice little machine.

I guess the main issue though is that if the machine won't power on, the seller cannot verify if the screen has tunnel vision, nor can they determine if there are dead pixels. EBAY prices for a good Portable are very high, and the 5126 seems to hover around US$1,000 right now, even untested! It blows the mind.

 

[Androda]

1: The Backlit Portable has a similar circuit to the "hybrid", just directly on the motherboard instead of on a dedicated separate PCB. It's very vulnerable to capacitor leakage, as the keyboard/trackball connector next to it has a few capacitors right there. @techknight would know failure rates better than me, but they could be similar.

2: As a semi-educated guess, I think the SWIM could die for a few reasons. First, if your hybrid (M5120) or power regulation circuit (M5126) dies, there's a decent chance that the main 5v power rail will see 7.5 volts right from the power adapter. That's well above safety margin and could be a cause of the SWIM dying / literally exploding (they do this from time to time). Other than that, maybe the SWIM used in this system is more vulnerable to capacitor leakage or there are internal electromigration problems directly in the silicon.

I agree with your points about "as/is" or "untested" systems. That is often a euphemism for "I know it doesn't work but would rather sell it for more money".

 

[moldy]

That is often a euphemism for "I know it doesn't work but would rather sell it for more money".

On the other hand, it's probably good if sellers don't try too hard to run those systems with a dead battery and old caps. Particularly M5120 with a problematic hybrid can simply fry logic including the Portable-specific chips (PMGR being the good candidate that is fried by >6V on the A/D line).

One more thing that came to my mind: there's a 4-pin molex (2x"+", 2xGND) coming from the battery. Make sure to always apply power to both "+" pins as they're not tight together. I remember @techknight pointed it out that if you apply power to only one of them, the power regulation circuitry might or will do weird things and apply >5V on the 5V rail.

 

[JDW]

On the other hand, it's probably good if sellers don't try too hard to run those systems with a dead battery and old caps. Particularly M5120 with a problematic hybrid can simply fry logic including the Portable-specific chips (PMGR being the good candidate that is fried by >6V on the A/D line).

That raises the question about cost and what is deemed "overpriced" though. The advice being given here is that "even if there's a working battery, unless the machine has been recapped, it's best if the seller does NOT try to power it on." And so, if they don't test it, it could have dead pixels, tunnel vision or other problems, right? And if there is a "high risk" of that (not sure how to define "high" though), and if the seller is trying to sell the machine for around $1,000 (and I've seen those prices on EBAY lately, is that too high in light of the risk to the buyer? If you have dead pixels, you can't fix that right? If you have tunnel vision, that would be a hard fix, right? And so, the question about what is really too high a price comes into question.

Again, I don't think we should be comparing to what prices were on EBAY 10 years or 20 years ago. I realize inflation stinks. But at the same time, the heart of my question lies in the fact that we are talking about an UNTESTED system selling for big bucks here. That's different than your other vintage Macs which are often tested. For example, somebody selling an original 128K Mac with original boxes for $2,000 most assuredly has tested the system and has maybe even recapped it too. But with the Macintosh Portable, we are taking an enormous risk on a completely untested system.

So I guess my question about price is really directed toward those of you who have a lot of experience with multiple Portables coming into your possession, as you would know the common problems and common fixes, knowing what can and cannot be fixed. You should be able to assess the risk of buying a high priced, untested Portable. I would appreciate hearing your thoughts.

Thanks!

 

[Androda]

That raises the question about cost and what is deemed "overpriced" though. The advice being given here is that "even if there's a working battery, unless the machine has been recapped, it's best if the seller does NOT try to power it on." And so, if they don't test it, it could have dead pixels, tunnel vision or other problems, right? And if there is a "high risk" of that (not sure how to define "high" though), and if the seller is trying to sell the machine for around $1,000 (and I've seen those prices on EBAY lately, is that too high in light of the risk to the buyer? If you have dead pixels, you can't fix that right? If you have tunnel vision, that would be a hard fix, right? And so, the question about what is really too high a price comes into question.

Yeah, that's the paradox you as the buyer will find yourself in.

As a "best practice" I would say you should send the seller a request for lots of pictures. If they are unwilling to open the battery bay, remove any batteries which are present, and take photographs of it from various angles then that's a hard pass. The battery area tells a lot of the story.

For example, if you see a leaking 9v battery the board is most likely going to be good for spare parts only unless you are willing to debug a mountain of possible issues.

If the motherboard (which is visible with battery cover removed) looks clean, there's no obvious nasty corrosion buildup, etc. then you're in better shape. That rules out obvious destruction, but cannot check issues which only appear at power-on such as the hybrid, display, etc.

So really I have no suggestions other than that. Decide how much you are willing to lose and roll the dice, is what it comes down to.

Also, don't be afraid to ask for partial refunds. I've bought systems from eBay listed as "good condition" which show up smelling like fish with parts rattling around inside. That's not good condition.

 

[Paolo B]

I’ve had 3 Portables, all non back lit (if you like oddballs, go all the way…). Sold one for ridiculously cheap money a long time ago, still have two. One dormant, one in full efficiency.

You surely need to rebuild the battery, recap the motherboard and replace the Conner drive.

The trackball rollers tend to deteriorate, but they are fixable.

Major issue with the non lit units: the lcd display may degrade and develop dead lines of pixels.

I don’t have enough statistics, but I tend to believe the issue goes with the production year or something.

Oldest unit I have is still perfect, the other one has progressively developed dead lines.

At a certain point I got a spare panel from a donor machine: arrived OK, but after some use all of the sudden dead lines appeared.

Something must be delaminating over time.

Shipment: if it comes with the original case (very nice) and considering the care from Japanese delivery companies, I would not expect any issue.

As for the pricing, on yahoo they recently go for 75k plus. A lot, but with money everything is relative.

Seems like here in Japan, because of the torrid weather and poor storage, displays get easily damaged, so finding good ones is very hard.

Anyhow, definitely one of my favorite 68k Macs ever, on par with the SE/30.

 

[sarnau]

Also annoying: there are no schematics for M5126 and while similar to the M5120, for debugging it is really annoying to fly blind.

 

[moldy]

Maybe one more hint: In my view, it's generally better to get a real "closet-find" find Portable that was untouched for years (provided that the 9v battery didn't leak) than something that already got "molested" by someone connecting it to power with a recap or trying to recap it without SMD soldering skills.

It is relatively easily to spot an untouched machine - if the feet are in place (on the keyboard edge of the bottom case), it usually means nobody has opened it recently. The feet are super crumbly after those 30 years and (even though I tried to be very delicate) always break while being removed. All 3 Portables I own had feet in place and had zero traces of fix attempts.

 

[Elemenoh]

I have several Portables and have helped some friends with others. Here are some things that I've dealt with.

I've had a couple with multiple stuck or dead lines on the screen. I tried cleaning the zebra connector but that didn't help and I wasn't able to find a way to fix them. I haven't seen a Portable display with tunnel vision though.

Others will warn against it, but I've had no problem running mine off of a higher amp power adapter or bench PSU and no battery. One of them was on display and running 10 hours a day for a year and never had an issue. That's not to say you wouldn't so take my experience as an anecdote. There's a project by @alxlab you can use to adapt a readily available battery or sub for super capacitors. If I was restoring a Portable now I'd probably go the super capacitor route.

I think it's pretty common that you'll hear audio distortion even post recap. IIRC a good cleaning will help, but I think there's some shielding deficiency in general. Maybe others here could provide more insight about that.

The internal SCSI connector is 34-pin. So you will need to build an adapter to connect a BlueSCSI or more modern spinning disk drive.

Get good photos of the bottom case. The plastics don't tend to be brittle like other models, but the weight of the thing can cause parts of the bottom case to crack if mishandled.

 

[Androda]

Adapters do exist for using a BlueSCSI with the Portable, on my site. These ones *only* work with BlueSCSI though, and do not present a Molex connector for use with a different drive style.

 

[ClassicHasClass]

Others will warn against it, but I've had no problem running mine off of a higher amp power adapter or bench PSU and no battery.

I killed one of mine (I had two originally) that way, though, so I'll argue the opposite side. My prototype Portable uses an original supply and a rebuilt battery and after its recap continues to perform perfectly except for its audio being a little quiet.

 

[JDW]

Adapters do exist for using a BlueSCSI with the Portable, on my site.

When clicking your link as of today, March 5th, choosing the low cost "Kit" shows OUT OF STOCK. Can we buy just the 3D printed Mounting Bracket from you? If so, how do we proceed with ordering that bracket-only?

If we cannot buy only the mounting bracket from you, could you please provide a link to the STL file for that bracket? (It didn't come up in my Googling.)

I have no means to print a mounting bracket myself, and Shapeways is extremely expensive, but perhaps I could call upon a friend to print one for me if the STL were available for download somewhere. I only need the bracket because I already have a BSv2 with Portable connector on it. And I have that special BSv2 only because @Jockelill very graciously shipped me one. It just didn't include the mounting bracket, hence my desire to obtain one.

Thank you!