Macintosh Portable Buying Tips

[Johnnya101]

Does anyone have some general tips on buying Portables? I bought one untested years ago, and got lucky with it working.

Looking for one again. I don't see a centralized buying guide for these things. Does anyone have some general tips?

I think I've heard the non backlits are generally easier to get going, but suffer from leaking caps badly. The backlits I think I heard have tantalums, but more finicky PMU? Obviously any higher voltage than 7.5 and higher amps than 1.5 have a chance to kill it, so don't get one that's been charged with the wrong brick, unless you want a project.

What else does one need to look for? What are the differences between the two models?

 

[moldy]

Given my recent journey with two Portables I'll try to answer some questions

The backlits I think I heard have tantalums, but more finicky PMU?

Backlits still have a few electrolytics caps which leak the same may as on the non-backlit version.
The power manager chip (PMGR) is the same and also compatible with Powerbook 100. The power circuits differ and the hybrid (a ceramic board in the corner of the logic board) is not present on the backlit model.

What else does one need to look for?

My advice: the feet of all Portables are quite brittle and they need to be removed to access the innards/mainboard. So Portables with all feet present were likely not tinkered with recently which I think is a good sign.

Beyond that, the 9V battery sometimes leaks too and destroys the memory chips and traces in that area. Watch out for that.

What are the differences between the two models?

Non-backlit (M5120) has a full original schematic available, backlit (M5126) doesn't (logic is more or less the same, but the power circuits differ considerably).
Non-backlit has a hybrid, which happily absorbs cap goo - the repairs/cleaning is a hit and miss and there's no direct replacement.
Non-backlit uses static RAM, while backlit uses pseudo-static RAM (cheaper, Apple tried to reduce costs).
Backlit is obviously backlit

Hope that helps!

 

[Johnnya101]

Given my recent journey with two Portables I'll try to answer some questions

Backlits still have a few electrolytics caps which leak the same may as on the non-backlit version.
The power manager chip (PMGR) is the same and also compatible with Powerbook 100. The power circuits differ and the hybrid (a ceramic board in the corner of the logic board) is not present on the backlit model.


My advice: the feet of all Portables are quite brittle and they need to be removed to access the innards/mainboard. So Portables with all feet present were likely not tinkered with recently which I think is a good sign.

Beyond that, the 9V battery sometimes leaks too and destroys the memory chips and traces in that area. Watch out for that.


Non-backlit (M5120) has a full original schematic available, backlit (M5126) doesn't (logic is more or less the same, but the power circuits differ considerably).
Non-backlit has a hybrid, which happily absorbs cap goo - the repairs/cleaning is a hit and miss and there's no direct replacement.
Non-backlit uses static RAM, while backlit uses pseudo-static RAM (cheaper, Apple tried to reduce costs).
Backlit is obviously backlit

Hope that helps!

Thank you, that helps tremendously! Which one would you say would be one that is the easier to repair/get going? Going off what you are listing, I would think the backlit.

 

[LaPorta]

One thing also: beware of Portables that come with a Powerbook 1xx power adapter and are advertised as "previously working." They probably screwed up the Hybrid circuits and who knows what else.

 

[moldy]

Which one would you say would be one that is the easier to repair/get going? Going off what you are listing, I would think the backlit.

I don't have enough experience to say statistically.
For sure the backlit version has the advantage of all components being "serviceable", with non-backlit if the hybrid is eaten away/cracked you're out of luck (hopefully at some point someone produces a replacement).

 

[desertrout]

For sure the backlit version has the advantage of all components being "serviceable", with non-backlit if the hybrid is eaten away/cracked you're out of luck (hopefully at some point someone produces a replacement).

Agreed - the hybrid is a consistent troublemaker, and many (most?) Portables have been bricked due to the hybrid's vulnerabilities. Based on this alone I'd say the backlits have better restoration potential.

@Johnnya101 I don't know if this is really a factor in your buying decision, but those original Conner hard drives are known to go bad, and their gaskets can turn to goo and leak internally on the drive platter or externally onto the case interior and motherboard (depending on how its stored). But the goo doesn't do any damage to the case or board, and sometimes the drives can be rescued. A working original drive may not be a big deal for you, and I'm not sure if it actually affects price.

A side note: techknight was toying around with the idea of redoing a hybrid, but you unfortunately need a known-good sacrificial one to work with... and no one wants to offer theirs up.

 

[Johnnya101]

I don't care for the original drives, so if it leaked or not won't matter. I've actually got what I think is a good, working one from my original portable that has had the gasket removed.