Use Mac Plus to repair 512K? Need help to make the choice!

[jsarchibald]

Hi all,

I need some help with a recurring question I have. I've got a Mac Plus, which has been upgraded from a 512K, and it is in great condition. Everything works the way it should, it's a great little machine. The only issue I have with it is that the case is yellowed only on the rear, the case that was changed during the '512K to Plus upgrade'. The front is still the 512K case, with 512K serial number. From what I know, this consists of a replacement of the motherboard, floppy drive, and rear case.

I also have a 512K with a front that has seen some slight damage, and it trips the circuit breaker when it is turned on. I got a startup chime from it before it tripped the CB. Looking inside, everything looks good, but the battery did leak and the analog board looks to have sustained slight damage. The only thing that looks wrong is some some of brown transformer has a bubbling inside it, and under the surface does not feel uniform. I think this may be the problem. The motherboard looks pretty good, no obvious issues.

I need your help in choosing one of the following courses of action:

- Leave them both alone and try to repair the 512K at a later date

- Take the motherboard and rear case from the 512K, and put it onto the Plus, effectively downgrading the Plus back to its original spec (what about the floppy, will it work or need to be swapped?)

- Put the 512K case on the Plus and leave it at that

- Some other option that may be good

Any help would be great, thanks guys.

 

[Mac128]

Floppy drive will work on the 512K or Plus.

Seems like if you want to keep the Plus the way it is would be to retr0bright it. Then it will all match. Unless you just want to downgrade to a 512K or 512Ke.

The analogue board of the 512K probably has corrosion that needs to be repaired among other potential problems.

 

[jsarchibald]

I guess what I am considering is putting the 512K motherboard and back case onto the upgraded Mac Plus I already have. Essentially, I guess I am wanting to return the Plus to it's original 512K spec, as it left the factory. The only thing making it a Plus is the mobo and case, as everything else is still 512K spec.

If the Plus wasn't in such good condition, I wouldn't have even thought twice about it. I want the Plus to return to its former glory, but I don't know if I will be ruining a very good example of a Plus or not. Thoughts please!

 

[TheNixer]

I think Mac128 has the answer. Retrobright the working 512/Plus conversion. If you think it's nice now, wait until you Retrobright it! Then, if you don't want to fool with it yourself, take your other Mac to someone and have it worked on instead of parting one out.

 

[Gorgonops]

If you're keeping the machines to use... or even if you're thinking of just putting them on the shelf to display, I really can't think of any good excuse to downgrade a Plus to a 512k. Anything a 512k can do a Plus can do better... the only known point of incompatibility (disk related problems with copy-protected software) you'll have on the 512k if you retain the Plus' double-sided drive. (The double-sided drives don't use the PWM signal to control rotational speed, which broke some particularly evil copy-protection schemes.) A hybrid made out of your best case parts and the 512k motherboard won't be an unmolested "numbers matching" collector's piece anyway, so why bother?

I'm sure other people will have contrasting opinions, of course.

 

[Mac128]

guess I am wanting to return the Plus to it's original 512K spec, as it left the factory. The only thing making it a Plus is the mobo and case, as everything else is still 512K spec.I want the Plus to return to its former glory, but I don't know if I will be ruining a very good example of a Plus or not.

Just to clarify, as you already know, the 800K drive in the Plus hybrid is not spec for a stock 512K. If you decide to restore the 512K, you would be advised to swap the Plus ROMs with the 512K making it a stock 512Ke (or 800K drive kit upgraded 512K). It will be more useful. Youll probably have to retrobright the 512K case anyway as it is unlikely the 512K bucket will match the bezel from the Plus hybrid, even though they may appear close. Of course you can always move the 400K drive over as well, and make it a true 512K.

Also you will have not much left after the "restoration" of the 512K, the Plus logic board will not have ROMs, nor a working analogue board. And depending on the extent of the corrosive damage, the analogue board may not be repairable. You will still have to retro0rite the case to make it presentable and the broken front bezel is not worth preserving. A Mac Plus can be had on eBay for relatively little money, so I don't see this as a hard decision ... Unless you intend to use a hard drive, or Zip drive. In which case you should restore the hybrid in order to have access to SCSI.

 

[jsarchibald]

Hi all,

I'm definitely not parting any machine I have, nor do I want to make money out of them.

However, I like the idea of having a machine worth more money, it makes me feel like I have a worthwhile collection (and the wife is impressed with a return on investment - she doesn't know I won't be selling them in time...). What is a Mac 512K upgraded to Mac Plus spec worth compared to a Mac 512? Which would be more of a rarity? This may also decide which way I go. With the current 512K, there is not much incentive to do much with it, as the front case is chipped and marked, the analogue board is iffy, and the machine looks like it has had some use. It may just end up being a parts machine for other compacts.

I am not the sort of collector who will be using this machine on a regular basis, or trying to utilise the RAM to do anything out of the ordinary.

 

[Mac128]

In that case, then restore it to a 512K which has slightly more collectors value than an upgraded Plus or an extremely common Plus. The 512K is identical to the original Macintosh, but with 384K RAM and a different bucket badge, for all practical purposes. Plus when you turn it on to show it off, you'll impress your friends with glowing red lights on the internal 400K drive, as well as the musical sing-song that drive makes while loading programs.

Also another important consideration is that the Plus logic board and 800K drive are harder on the 512K analogue board, so you will put more stress on a system that wasn't really designed to support the upgrade, thus dooming it to failure faster than running it as designed.

Personally, I think the Plus upgraded 512K is just as interesting a model for a collector as the Macintosh ED in Platinum. However, most don't even consider it a model, despite the fact that Apple ordered all remaining 512Ke stock at the end of the model life to be upgraded to the Plus, and it was actually sold new, off the shelf in that configuration.