"Macintosh"

[bunnspecial]

I had the opportunity to buy this recently.

It just arrived today, so I haven't taken it apart to document the LoBo(something which I will do in due course). The floppy drive also won't accept a disk, but fortunately I was able to boot it via an external.

This was bought from its original owner, and I'll see what I can get out of him about its history. I don't THINK it's had a RAM upgrade.

The SN decodes to the 17th week of 1984, which if I'm counting correctly means April 22-27.

 

[bunnspecial]

Looks like it's all original 128K. The floppy drive came to life with a ltitle bit of cleaning and lube.

 

[MacTech68]

Wow - impressive that somebody never upgraded it.

Interesting with the week numbers - I suspect this machine MAY have been pulled off the production line due to a fault, and subsequently refurbished with a factory repaired motherboard 2 weeks later.

Note the OKI RAM ICs seem to have been manufactured Week 18 of 1984. Then there is ONE replacement Motorola dated Week 19. Since the RAM ICs are likely to have been the most rare part back in 1984, it's likely those dates are true.

Could it have been an Apple Service repair instead? Yes, that's likely too, but given the closeness of the manufactured dates of the OKI and Motorola RAM, I'm leaning towards a factory refurbishment - ie, this might be how it left the production line after failing initial testing.

The other parts that seem to be very late to a Mac128 motherboard (ie - in short supply) are the D-sub connectors (these usually have a 4 digit date stamp too).

Other ICs in your picture show a Week 08 of 1984 manufactured date - these would have been in plentiful supply at the time.

EDIT:-
- also note that the board already has the revision of the resistor pack attached to the 6522.

I'd love to see the Analog board.

 

[bunnspecial]

Thanks for your input and information on it. My "gut" after looking was that this one was all straight, and I appreciate your confirmation and observations.

I will pull it apart again and document anything requested-I know that finding one that was never upgraded can be an adventure in and of itself, so I want to put all I can out on this computer. I'll do a quickie snap of the analog board for you, but I lose the picture occasionally on it(it will come back with a smack on the side) so I need to redo the flyback solder joints. I'll fully photograph the analog board when I do that.

 

[MacTech68]

If when you lose the picture, the screen is completely blank, then this is most likely a bad solder joint on the video pin of the 10pin power/video connector.

The pic below is with the screen facing downward.

 

[bunnspecial]

Here's a photo of the lobo. I'll get the analog board tomorrow.

This is the full res image

https://drive.google.com/open?id=1FpidratOCuHgLzLN1mh9nmrsBC0FeFeB

 

[MacTech68]

Love it - thank you.

Looks like one of the last ICs was the Zilog 8530 (Week 20 1984) - some of the PAL ICs were very late too, like The BMU0 at E19 is Week 19.

 

[bunnspecial]

Thanks again-it looks like you were correct that it was reworked and sold a few weeks after initial production.

All of the joints consistent and very clean, so I suspect that everything on the board was done at the factory. I know that finding one that hasn't been upgraded or repaired is somewhat uncommon, so I want to document this as best as I can.

[doublepost=1527345405][/doublepost]Also, here's the analog board

 

[MacTech68]

Certainly appears to be a factory replacement.

The Class X2 Capacitor on your analog board seems to have already popped.

The Analog Board also looks like a later replacement. I see a flat-pack rectifier bolted to it's heatsink on the power supply output and a litzwire horizontal width coil.

Battery has leaked and there is rust on the chassis frame.

Just making observations - no doubt you have seem some of these.

 

[bunnspecial]

Here's the analog board out.

From reading some past comments on here, have an all original analog board would be really unlikely, so I'm not surprised that it's a later replacement.

 

[MacTech68]

Nice pics.

I'd guess this board was from an original 1984 Week 38/39 - it looks to have had it's last major repair around Dec 1987.

Apple mods & component 'upgrades' are visible, but it's certainly NOT the most upgraded board. This is fairly early in Apple Service's learning curve.

If required I can point out all the modifications I see.

I fear that the battery leak has done this board a disservice. Unprotected metals are having a hard time on this board (corrosion). I fear that there will be a number of completely black solder pads and tracks on the other side. Sadly, this is common from battery leaks - a feature I never used to see these boards in. It's like seeing an old friend looking worn out and ill.

 

[amagichnich]

This certainly was a lesson! Thx guys!

If required I can point out all the modifications I see.

I saw, well, 2 things that seemed strange. Now how many hours have you spend with these machines to be so skilled?

 

[MacTech68]

This certainly was a lesson! Thx guys!


I saw, well, 2 things that seemed strange. Now how many hours have you spend with these machines to be so skilled?

From 1984 to (roughly) 1996 - component level repairs. AppleII machines before that.

 

[amagichnich]

From 1984 to (roughly) 1996 - component level repairs. AppleII machines before that.

Sounds like quite a lot of hours wow, I'm impressed

 

[MacTech68]

Sounds like quite a lot of hours wow, I'm impressed

In reality, it was just a job - one that gave me a lot of experience.

 

[bunnspecial]

If required I can point out all the modifications I see.

I was just looking back at this thread and realized I never took you up on this. I'd still be interested to know if you see this response and have the time and willingness to still do so.