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"broken" Compact Mac Lot

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platatomi

Experienced Member
Joined
Dec 13, 2011
Messages
91
Just picked up this lot of "broken" compact Macs. The models are as follows:

1 x original 128k
1 x Plus
2 x SE
1 x Classic


And an ADB keyboard + mouse. Heres the group shot:

DSC_2097.jpg


And the grand total for this lot: $55. Even not working, thats a great deal.

I'd like to start with the 128k, it powers on and gives me a sad mac, with 040010 below that and some white dots in a vertical line on the left side of the screen. So far I have tried reseating the ROMs and that didn't help. How should I go about troubleshooting this?
 
http://support.apple.com/kb/TA46376 This says that the error i'm getting is a memory error, and identifies the chip that is the problem, the F9 RAM chip. I notice on this chip that one of the pins appears to lack solder on the top of the board, but that pin is soldered on the bottom. Is that a problem?
 
Pretty sure you will just have to replace that RAM chip to make your Mac happy again. You may have some additional bad RAMs that will be revealed once you fix the F9 chip. I've done this on a couple of sad 128s that I've come across, and had to replace a few chips each. You will need 4164 DRAMs, I got mine from Jameco. I believe 41256 DRAMs will also work.

I found that the easiest way to remove the chip is to clip the legs off of the chip, then remove each pin individually. Good luck!
 
Tried to take a picture but I can't get anything that clear enough to be any good.

This is what most of the pins on the RAM chips look like, solder on the top of the board, filling the hole that the pins go through. But one pin on F9 has no solder around it, it just goes through the hole.


I know these aren't the same chips i'm talking about, just grabbed the image.

dscn0161.jpg
 
I would venture a guess that the solder on the F9 pin is not the real issue. You could check continuity between the pin at the chip body and the trace at the bottom of the board, but I think there's a high chance that the F9 chip is just bad and needs replacement. So far for me in doing some repairs on various old computers, bad RAM has been the most common problem, with bad ROMs a close second. I've been lucky to find a few Mac 128s lurking around here and there, and all but one of them had some bad RAMs that needed replacement.
You can also try piggybacking a new 4164 chip over the F9 chip and see if that changes anything..
 
gubbish said:
Pretty sure you will just have to replace that RAM chip to make your Mac happy again. You may have some additional bad RAMs that will be revealed once you fix the F9 chip. I've done this on a couple of sad 128s that I've come across, and had to replace a few chips each. You will need 4164 DRAMs, I got mine from Jameco. I believe 41256 DRAMs will also work.

I found that the easiest way to remove the chip is to clip the legs off of the chip, then remove each pin individually. Good luck!
Click to expand...


Ok, thank you for the link, I'l give that a try. Now on to the other machines....
 
Got both SE's going, they weren't working for the strangest reason! Somebody decided to unplug the thing off the end of the CRT, disabling video output. This is what I saw when I open up both SE's:


DSC_2104.jpg


Just plugged that thing back in and now I get video! They are both working well now, besides some sticky floppies and a grinding hard drive.

That makes 2/5 working so far!


I'd like to ask about one problem with the second SE - the video now works but the display isn't nearly as bright as it should be. Yeah, I upped the brightness all the way with the nob and its still WAY dark. What's up with that?
 
Great that you got the SEs working.. I'm not sure about the brightness issue, it sounds like there may be a resistor that needs to be adjusted or something.
You may want to post this over on the http://68kmla.org forum. The folks there are very knowledgeable about compact Macs and I'm sure someone there will know.
 
gubbish said:
Good luck with it.. what are the symptoms of the others?
Click to expand...


Both SE's and the Classic showed no video at all, the Plus was garbled but recognizable.


And I actually just fixed the Plus - Knowing that the frambuffer is in system RAM and the machine was hanging on boot, that tells me there's a memory problem. So I just reseated the RAM cards, the picture is great now. But it is finicky - the video cuts in and out due to a loose connection somewhere (I think on the analog board or cable from analog to motherboard), giving the thing a tap on the left side usually fixes it.


Just opened the Classic - bad news. The CRT is broken, literally. The hard drive is grinding and the cases full of debris. The motherboard may still work but won't know without a screen. It also has a RAM expansion card, a "MACRAM CLASSIC" which looks ok. Not a total loss.

That makes 3 of the 5 "broken" Macs working.
 
Good work on the Plus. That flaky video symptom with the tap on the side remedy is a common thing with the Mac Plus and is discussed in many threads over at the 68kmla site. There are some repair options for this. I have a Plus which started out with video cutting in and out and now is just out. I believe there are a few capacitors that should be replaced on the analog board. I have a compact mac repair document from someone at the 68kmla site that discusses this problem which I can send you if you like, just send me a PM.
 
The "video cutting out" and flakey video is a common problem, as is the display collapsing into a single vertical or horizontal line. Resolder the flyback transformer, the deflection yoke connector, and anything else that looks like a poor connection. Bad solder joints in these are quite common. There is also a bipolar electrolytic that goes bad frequently, but since it's working and intermittent, your problem is solder joints.

The Mac 128 is definitely a RAM chip. Replace it you should be back in business.

The dim SE could be simply a weak picture tube. You can adjust the SCREEN voltage on the analog board, but if you can't get it brighter with adjustments, it could be a weak tube. Usually you see them on Macs with a lot of screen burn (the top menu visible when the computer is off), as the tube has a lot of hours on it and the emissions aren't what they should be. It's possible to "rejuvinate" a weak picture tube, if that is your problem, but it requires a special piece of equipment.

-Ian
 
RetroHacker_ said:
The dim SE could be simply a weak picture tube. You can adjust the SCREEN voltage on the analog board, but if you can't get it brighter with adjustments, it could be a weak tube. Usually you see them on Macs with a lot of screen burn (the top menu visible when the computer is off), as the tube has a lot of hours on it and the emissions aren't what they should be. It's possible to "rejuvinate" a weak picture tube, if that is your problem, but it requires a special piece of equipment.

-Ian
Click to expand...

Yeah it looks like the tube is worn out. I tried adjusting that screw thing on the analog board - it got brighter but also started showing those horizontal lines and became really fuzzy. In bright light I can see the ghost of the menu bar when the things off, so definitely a worn tube.
 
If you want to do some calling around, check to see if a TV shop will "zap" it for you on the rejuvinator. I've got one, and I've had luck bringing life back to worn Mac tubes in the past. It's a standard tube pinout, and if you find an old shop they probably still have the equipment (and someone that remembers how to use it!)

Or, you know, just find another tube/Mac - they're really common :)

-Ian
 
There actually was a great TV/Appliance repair shop just a few blocks from me, but they closed down about year ago. Guess the CRT business is drying up. Anyway, the dimness seems to have gotten a lot better, maybe just needed a little use after sitting idle for years. Because the case is really ratty i'm gonna use this for a test machine for other components, so its not really a problem.
 
OMG! Replaced that F9 DRAM on the 128k And it works! Thank you guys so much for the advice!

Pretty sure you will just have to replace that RAM chip to make your Mac happy again. You may have some additional bad RAMs that will be revealed once you fix the F9 chip. I've done this on a couple of sad 128s that I've come across, and had to replace a few chips each. You will need 4164 DRAMs, I got mine from Jameco. I believe 41256 DRAMs will also work.

I found that the easiest way to remove the chip is to clip the legs off of the chip, then remove each pin individually. Good luck!
Click to expand...

And thank you again gubbish for the link!


Its sad to think of how many of these injured but easily repairable machines bit the dust because people weren't willing to crack to case.
 
Looks like the next problem is the floppy drive, I can't get a disk in. It gets stuck just inside the slot and then takes a yank to pull out. I've played with a lot of floppy drives but of course these single-sided 3.5 drives are unique. Any common problems with these or troubleshooting?


Just to boot a disk to see this thing work, can I put an 800k drive in? I know it won't read 800k disks but really want to boot this thing.
 
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