Duo 270c - Yay or nay?

[Garrett]

A couple days ago, I posted this PowerBook Duo 270c for sale somewhat locally (about 60 miles away) for $75. My current Mac collection consists of 68000-powered compact Macs, and I'd like to get into something with a little bit more power and a color display. Therefore, the Duo 270c has captured my attention. Even better, it's a laptop so it won't take up a whole lot space.

Are the Duo 270cs pretty reliable? I know the PowerBook 1xx models are notorious for having display issues, as well as problems with plastics and the hinges. Does the 270c have a serial connection for connecting to my compact Macs to load files and software, and is there any options for replacing the hard drive with something modern should it fail?

Should this be the next addition to my collection? Or should I save my money for a different 68030 machine, such as an LC III or something? Any input is greatly appreciated.

Facebook Marketplace link: https://www.facebook.com/marketplace/item/365835497985279/

Images by the seller:

 

[androda]

The Duo 270c does have a standard 8 pin modern port which you should be able to use for localtalk. But that's it, no floppy drive or anything else without a dock.

Internal hard drive is scsi, so you're looking at scsi2sd or similar.

LC III has a slower CPU and system bus, but you can add an Ethernet pds card and don't need a dock for expansion or the usual ports (ADB, etc). Scsi drive in the LC III, so same difference on that one.

The main difference between LC III and duo in terms of longevity is that the LC absolutely needs capacitors replaced. They always leak. The Duo series is a bit of a mystery to me on whether they require capacitor replacements all the time. My PB 190/5300 aren't leaking yet, and my 2300 mobo with 280c screen is also not leaking. Of course these checks are done visually so I can't see if there's leakage underneath.

 

[maceffects]

If you don’t want it, buy it and I’ll pay $150 for it  

 

[maceffects]

That was my first laptop and I used it for years. If I were you I’d recap the logic board.  Other than that they are reliable, although the keyboards sucked even when new. The active matrix screens are nice. 

 

[LaPorta]

Just as an aside, every Mac from the Plus through the B&W G3 Towers (excluding iMacs only, to my knowledge), had the same serial ports and can network with AppleTalk with System 7 and greater with each other.

 

[Byrd]

Hi Garrett,

PB Duos are fantastic machines but I'd not buy one as your go to portable vintage Mac - they're good to have in the collection but IMO not as a "daily".

They are reliable Macs, minimal caps to replace, however ideally you need a mini dock for connectivity (SCSI, floppy) and the keyboard on PB Duos is horrible to use.

JB

 

[mdeverhart]

PB Duos are fantastic machines

I’d second that. I have a 230 I’ve been restoring, and I’m really enjoying it. That said, like all vintage Macs, there are things to be aware of:

1. Capacitors are absolutely necessary. There are two main groups of leaking caps: (1) In the power supply section of the main logic board, and (2) in the display assemblies (varies depending on the model - my 230 has some on the display board around the LCD but none on the inverter board for the backlight, but my understanding is that some models do have them there). The main logic board ones are the biggest concern. Due to the battery charging and power management circuit, that section of the MLB has 24-28V. When the caps leak, they can short that high voltage onto logic chips in the area, or on the backside of the board through vias. If that happens, it can easily blow out the 5V logic chips, or wreck the power manager circuit. That’s basically fatal. I don’t think the display ones are as dangerous, but they can definitely cause problems - my 230 is down at the moment until I can replace these, as the bottom 1/4 of the screen is basically shorted out. There are threads on this board about the duo caps for reference.

2. The keyboards are really pretty bad. They’re early, relatively low profile (for the time) membrane keyboards, with way too much flex. You can improve them somewhat by cleaning the membranes (carefully), or fitting a very thin piece of aluminum or other sheet metal behind it, but that’s about it. (I’ve not tried the sheet metal fix). The third (?) generation keyboard that came in the 2300s is better, and (I think) was available as a service part for other models. If you can find one I believe you can install it into any model.

3. The rechargeable PRAM battery will probably need to be replaced, and it’s not a standard part. The PRAM battery is part of the power manager circuit, and having a dead one can lead to some additional side effects. At least on mine, applying power (plugging it in, docking, etc) when the battery is dead can cause the power supply on the circuit board to start rapidly clicking. Pressing the power button on the back of the machine (not the one above the keyboard) would boot the machine and the clicking would stop. Clicking switched mode power supplies make me very nervous, so that made me quite anxious until I got/made a new battery.

All of that said, $75 is a steal if it’s in working order. They don’t come up often on eBay, and I feel like they’re close to or over $200 for working ones. I don’t think you’d be able to find any other 030 for that price either, unless you buy it locally. eBay prices are just nuts at the moment. If you end up not liking it, you’ll easily get your $75 back here or on eBay. This all assumes it’s working. The leaking caps on the MLB are the main risk - if those caused a destructive short it’s dead. If you get it, recap the MLB as soon as you can. 

 

[Trash80toHP_Mini]

A couple days ago, I posted this PowerBook Duo 270c for sale somewhat locally (about 60 miles away) for $75. My current Mac collection consists of 68000-powered compact Macs, and I'd like to get into something with a little bit more power and a color display. Therefore, the Duo 270c has captured my attention. Even better, it's a laptop so it won't take up a whole lot space.

I'd definitely go for it if space is a concern. The 270c is unique among the 68K Duos as it's the only one with 68882 support. The other 030 Duos lack it as does the 68LC040 in the 280. All but the 270 relied on using a math chip in the Dock.

Should this be the next addition to my collection? Or should I save my money for a different 68030 machine, such as an LC III or something?

I'd say go for it, try it on for size and if you don't like it you can flip it to @maceffects

 

[Garrett]

I messaged the seller a couple days ago and no response. I think the Duo 270c would be the perfect addition to my collection... let's just hope they still have it.

 

[Garrett]

Heard back from the seller. Thankfully, it's still available. Now I'm working on setting up a time to meet to pick it up. I will try to avoid turning it on until I get it recapped.

How hard is it to remove the logic board from the Duo 270c? As previously mentioned in another thread, my track record for working on laptops isn't very good - which makes me nervous. Also, how hard is it to replace/fabricate a new PRAM battery?

P.S./OT - I also have a lead on a Apple Cinema display for a really decent price. Does anyone know if it'd be possible to use it with my 2019 13" MacBook Pro, and what adapters I'd need? I used one of those at a previous job and it was an excellent display.

 

[maceffects]

Just be careful when opening the plastic case to get inside. Don’t break the clips that are no doubt brittle. It’s actually not a hard process so much as a risky process. Simply recap the logic board and you’re good to go. 

 

[LaPorta]

Cinema display with what sort of connector? You mean the LED Cinema DIsplay with Mini Displayport? I still use my 2010 LED Cinema Display 27" with my new 2020 iMac. Just need a Mini DisplayPort to USB-C adapter. Can be found for relatively cheap on Amazon.

 

[Garrett]

Just be careful when opening the plastic case to get inside. Don’t break the clips that are no doubt brittle. It’s actually not a hard process so much as a risky process. Simply recap the logic board and you’re good to go. 

That's what I'm afraid of, as I know Macs from that time period (mid-90s) are notorious for having super brittle plastics. Any tips on opening it? Would it be fine to ship the entire machine when recapping so my "recap expert" has a machine he can test with?

I'm looking to pick the machine up this Saturday, but I may have to set it aside for a couple months until I have the time/money to have it recapped.

 

[Garrett]

Cinema display with what sort of connector? You mean the LED Cinema DIsplay with Mini Displayport? I still use my 2010 LED Cinema Display 27" with my new 2020 iMac. Just need a Mini DisplayPort to USB-C adapter. Can be found for relatively cheap on Amazon.

First, sorry for the double post. Your post didn't appear until after I replied to maceffects.

Here's the link to the Cinema HD Display listing. DVI? https://www.facebook.com/marketplace/item/769947730263016/

 

[androda]

That's what I'm afraid of, as I know Macs from that time period (mid-90s) are notorious for having super brittle plastics. Any tips on opening it? Would it be fine to ship the entire machine when recapping so my "recap expert" has a machine he can test with?

I just opened my 280C to replace capacitors. It's not that bad aside from the display center hinge cover. That thing is a nightmare, haven't found a good system for removing yet. And some of the body screws were broken out of their brass inserts (not by me, broken before opening).

As for shipping the whole machine, that might make the most sense simply due to the fact that duos don't have a display output port. Need to make sure it tries to boot up

 

[Challenger 1983]

I just opened my 280C to replace capacitors. It's not that bad aside from the display center hinge cover. That thing is a nightmare, haven't found a good system for removing yet. And some of the body screws were broken out of their brass inserts (not by me, broken before opening).

As for shipping the whole machine, that might make the most sense simply due to the fact that duos don't have a display output port. Need to make sure it tries to boot up

Out of curiosity, what kind of capacitors did you use?, did you replace the electrolytics like for like? 

 

[androda]

Haven't actually done the replacement yet, just pulled the old ones and did a board wash. I do prefer to use electrolytics for replacement just because that way I don't have to worry about derating, differences in leakage current, etc.

Need to give the solid polymer capacitors a good look though. Those seem better than tantalum long term, less likelihood of blowing up.

 

[mdeverhart]

Getting the logic board out to do the caps isn’t bad at all. The most important thing is to get the latch inside the battery compartment (on the front left inside of the battery compartment) unhooked, and you can see that one and use your fingers to get pressure in the right place. Fortunately you don’t need to take the center clutch cover off in order to get the logic board out - that one is a pain. For the logic board you can remove the CPU stiffener and display assembly as one piece. You only need to remove the center clutch cover if you need to disassemble the display or take the display off the CPU stiffener.

I have the service source documentation for the 200 series duos, including disassembly instructions. PM me if you want a copy.

For the logic board I used the solid polymer capacitors, for similar reasons as androda described. I also like that they match the original look. Here are the ones I used for my 230 - I don’t know what the 270 used, but you can probably find the right values/rating in the same series.







Value



Voltage



Manufacturer



Part Number





100uF



35V



Nichicon



PCV1V101MCL1GS





100uF



25V



Nichicon



PCR1E101MCL1GS





330uF



16V



Nichicon



PCV1C331MCL1GS





33uF



25V



Nichicon



PCV1E330MCL1GS






The Nichicons were the only ones I could find for a few of the values that were shorter or the same height as the originals - important, since they’re underneath the metal CPU stiffener. I didn’t want to got to the trouble of installing new caps only to find that they hit the stiffener when reassembled.

I’ll try to post some notes tomorrow on building a new PRAM battery.

 

[maceffects]

The case is NOT as brittle as desktop Macs from the similar era. But I would still use caution.