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platatomi
January 30th, 2012, 09:26 PM
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:

7735


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?

Compgeke
January 30th, 2012, 09:30 PM
Sad mac...is there a floppy in the drive? That can occur if the OS is incompatible with the system.

platatomi
January 30th, 2012, 09:34 PM
No floppy in the drive, also tried with drive unplugged - same thing.

platatomi
January 30th, 2012, 09:49 PM
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?

Compgeke
January 30th, 2012, 10:00 PM
Do you have a picture? I've never seen anything soldered on the top that can be hand soldered...seems impossible really.

gubbish
January 30th, 2012, 10:11 PM
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 (http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_41662_-1). 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!

platatomi
January 30th, 2012, 10:15 PM
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.

http://systemfolder.files.wordpress.com/2009/11/dscn0161.jpg

gubbish
January 30th, 2012, 10:28 PM
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..

platatomi
January 30th, 2012, 10:31 PM
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 (http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_41662_-1). 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!


Ok, thank you for the link, I'l give that a try. Now on to the other machines....

gubbish
January 30th, 2012, 10:37 PM
Good luck with it.. what are the symptoms of the others?

platatomi
January 30th, 2012, 10:37 PM
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:


7736


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?

gubbish
January 30th, 2012, 10:49 PM
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.

platatomi
January 30th, 2012, 11:01 PM
Good luck with it.. what are the symptoms of the others?


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.

gubbish
January 30th, 2012, 11:19 PM
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.

RetroHacker_
January 31st, 2012, 05:31 AM
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

platatomi
January 31st, 2012, 01:41 PM
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

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.

RetroHacker_
February 1st, 2012, 05:33 AM
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

platatomi
February 1st, 2012, 04:46 PM
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.

platatomi
February 3rd, 2012, 01:28 PM
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!

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.

platatomi
February 3rd, 2012, 01:35 PM
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.

gubbish
February 3rd, 2012, 01:48 PM
I think your drive just needs a little cleaning/degunking. This has been the case on pretty much every mac 128 I've seen. The mechanical parts are frozen with dried old grease and need re-lubricating.
You'll have to remove the drive and look for the joints on the drive that are stuck. I have a link somewhere with a visual guide for doing this, I'll take a look.
People have used different substances for this, but I put some WD-40 on a q-tip and carefully scrubbed around the joints where grease had dried up. It's a repetitive process, and I used a junk 3.5" disk to test the mechanism, just keep inserting it and checking if things were moving correctly. I think there are about 4 or 5 points that are usually frozen up keeping the mechanism from moving. I've seen it recommended to add lithium grease to the joints after cleaning the old grease off but I have not done this on mine.

platatomi
February 3rd, 2012, 02:05 PM
I did get it freed up, but it still acts strangely - like there's a disk inside when there isn't. Unless I hold the eject lever down, the tray is dropped and the little guard things at each side of the opening prevent a disk from being inserted. When connected to the computer it acts the same way, I see no response whatsoever from the motorized eject mechanism.

dorkbert
February 3rd, 2012, 02:22 PM
400k drives commonly have ejection mechanism problem. we used to send them out to have them "refurbished."
You ... could use a 800k drive with a few caveats (http://68kmla.org/forums/viewtopic.php?f=29&t=17418), but the mounting holes won't line up properly. I've seen home-modification done to mount 800k drive in the internal 400k mounting bracket before. You could also swap out the ROMs to 128k so you can boot from and format with 800k drives...

platatomi
February 3rd, 2012, 02:27 PM
Good to know I have a plan B. It turns out the ejection problem was caused by more sticky parts, wasn't very apparent at first. Its not quite working yet, needs a little more manual exercise but should get there.

gubbish
February 3rd, 2012, 02:29 PM
BTW, forgot to mention - congrats on getting the 128's motherboard working! Always a good feeling..

RetroHacker_
February 6th, 2012, 05:17 AM
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?

This is a really common problem. As others have said, it's the grease that used to lubricate the mechanism. You can disassemble and remove the whole disk carrier mechanism, and spray it with WD40 to dissolve the grease, and clean it up. Relubricate with a little white lithium grease, and put it back on the drive. DON'T spray WD40 at it while it's on the drive! You don't want to get that junk on the board or the disk head. While you've got it apart, clean the head with isopropyl alcohol on a q-tip.




Just to boot a disk to see this thing work, can I put an 800k drive in?
Yes. You can also attach an external 800k drive from a IIgs and it'll work. Just, only as a 400k drive. You need the Plus ROMs to use 800k drives.

-Ian

tezza
February 7th, 2012, 10:16 AM
BTW, forgot to mention - congrats on getting the 128's motherboard working! Always a good feeling..

Ditto from me. There is nothing quite so satisfying as watching a dead machine spring back to life. A Mac 128 is something I want in my collection. Someday perhaps...

Tez