Help! Macintosh plus freezes upon booting up

Question

Level 1

8 points

Help! Macintosh plus freezes upon booting up

I bought a macintosh plus 1MB from ebay, and it worked fine. then after two days, it froze. I did not have a system disk in the floppy drive at the time. Nothing seems to respond except the power switch (duh), and to see what would happen, I put a floppy in the drive, but I didn't hear the read/write heads whirring, nor does it want to eject. Even the interupt/reset switches don't do anything. When I turn it on, for a brief moment before the CRT comes on, things do respond. but only for a second, then it freezes. The screen works with no problems even when frozen, but the floppy disk icon does not flash, and the mouse does not move. It did work when it came in the mail, and I have not removed the motherboard, or anything else, though I did pop the case of to adjust the CRT (the image had "shrunk" a little). I am thinking the RAM went bad or something, since that would keep the system from working, though that would not make sense, since it works for a brief second after power up. Any help whatsoever is much needed, as I had high hopes of the machine working.

Macintosh Plus 1MB-OTHER, Mac OS 8.6 or Earlier

Posted on May 29, 2013 3:37 PM

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Answer 1

Jan Hedlund

Level 7

22,387 points

May 30, 2013 1:40 AM in response to Redblock307

It is of course difficult to determine a cause here. One guess and possibility could be that the low voltages (5 and 12 V) vary, perhaps because of a cracked solder joint or a faulty component (electrolytic capacitor?). It is probably not a bad idea to measure the low-voltage levels with a digital multimeter under different situations to begin with (a link to a PDF file with information about how to do this via the external floppy drive port can be found under References in the Macintosh Plus Wikipedia article).

Please note that a compact Macintosh computer contains high-voltage circuits. Opening the computer can be very dangerous. A computer disconnected from the mains can keep charges in various components for a long time. All work inside must be carried out only by someone with the necessary expertise.

Jan

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Answer 2

Redblock307 Author

Level 1

8 points

May 31, 2013 4:43 AM in response to Jan Hedlund

Yes, it could be hard to determine the problem, but I think I'll pop the case of again and clean the ram and rom and look for dry solder links.

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Answer 3

Redblock307 Author

Level 1

8 points

May 31, 2013 1:19 PM in response to Redblock307

Well, turns out it might just be the PRAM battery or whatever. A (Unnamed) Relitive came over and saw the macintosh (insert happy face) and somehow got it "running". but after Mr.unnamed removed the PRAM battery, it started up. Sort of. It turns on, sometimes frozen, and sometimes not, and after inserting a system disk (Huge thanks to rescuemyclassicmac.com), the top half of the screen went dark. It came back on after a reboot, but it happend a few more times. The main problem is that it is still "half frozen", as in the fact that half of the time it still doesn't work.

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Answer 4

May 31, 2013 6:09 PM in response to Redblock307

You might want to check out this site, which has some helpful troubleshooting tips for SEs:

http://www.ccadams.org/se/screen.html

It sounds like you might still want to go over the board looking for cold solder joints; especially on the analog board. Of course heeding Jan's advice about safety is of primary concern, especially as it's been running recently.

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Answer 5

Redblock307 Author

Level 1

8 points

Jun 1, 2013 8:51 AM in response to JustSomeGuy

Thanks for the link, but I think that the Plus not having a PRam battery might be part of the problem. I ordered a new one a day ago

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Answer 6

Redblock307 Author

Level 1

8 points

Jun 4, 2013 5:27 AM in response to Redblock307

I got it to boot from a system disk once, and it worked quite well. turned it off, never happened again. :( I trumped the darn old thing a few times before booting it, so it must have been a loose connection.

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Answer 7

Jun 4, 2013 6:10 AM in response to Redblock307

Yes, definitely a cold solder joint in there somewhere. My plus is the same way... I have to whack it ever harder on the side to get the monitor to come on. I'll open it up soon and do some PM.

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Answer 8

Redblock307 Author

Level 1

8 points

Jun 5, 2013 5:06 AM in response to JustSomeGuy

Yes, that would seem to bee the case. But one odd thing.. when there is a disk in the drive, and the keyboard is UNPLUGED, the system reboots itself until I plug it back in. And, how should I go about fixing a cold solder joint (does that mean it cracked)?

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Answer 9

Jun 5, 2013 6:02 AM in response to Redblock307

Redblock307 wrote:

[...] how should I go about fixing a cold solder joint (does that mean it cracked)?

A cold solder joint really refers to any of a number of problems due to a poor quality soldered connection. It's most easily caused by improper heating of the joint or mechanical movement during (or after!) the cooling proces. A good discussion of the phenomenon is here:

http://www.polkaudio.com/forums/showthread.php?30230-What-is-a-quot-cold-solder- joint-quot

How you fix it is to "reflow" the joint; that is, heat the joint back up with a soldering iron to the point where the solder becomes molten again, and re-connects the faulty joint. How you find them is much more difficult. Close inspection may reveal dull, greyish joints or even cracks/fissures in the solder blob. It's a common problem in the Mac Plus analog board (which is what currently ails my whackable Mac).

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Answer 10

Redblock307 Author

Level 1

8 points

Jun 5, 2013 4:56 PM in response to JustSomeGuy

From what the article says, I don't think I want to look for one specific link outbid the hundreds on the board. :/

Inreally hope that a new pram battery will fix it.

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Answer 11

Redblock307 Author

Level 1

8 points

Jun 6, 2013 1:04 PM in response to Redblock307

I just got a new 4.5 V PRAM battery, but that didn't change anything. (sadface)

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Answer 12

Jun 26, 2013 12:56 PM in response to Redblock307

This occasionally happens to my Mac Plus. I'll turn it on and there will be the plain gray screen without any icons or anything else on the screen.

It can be tricky to diagnose and fix, but you may be able to fix it.

A fairly common source of issues these days for old all-in-one Macs is often the capacitors. They tend to start to leak over time and go bad. They can be replaced, but you have to be willing to solder new ones. I believe old caps are causing a problem with my Classic, which has some sound issues.

Replacing the battery and zapping the PRAM might help. It's probably the easist to do. Also try removing everything from the computer and turn it on just to rule out any bad accessories.

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