Mac Plus endless re-boots

#1 Sun, 9 Aug 2009 - 17:34 68kMLA

Ok then - Mac Plus, it boots, or rather it can boot all the way to the desktop and it can sit there for a while - usually less than ten mins - then it re-boots. it generally gets to the desktop when it is first switched on. but not always.

now then - if i leave it to re-boot then it may or may not get to the desktop before rebooting again. sometimes the chimes dont finish before it tries to reboot again.

thats the problem - observations and stuff so far.

i have washed the board, i have swapped ram about i have looked for dodgy solder joints on the video board and around the power connector.

one other thing - when the machine is first switched on, it takes, what seems an age to start the boot process, it just sits there with a grey screen. in my opinion it sits there way too long before trying to boot. that suggests something to me, but what?

any help?

cheers

#2 Sun, 9 Aug 2009 - 18:15 68kMLA

On a cold boot with 4Mb a MacPlus does take a fair amount of time to go through its memory. That is normal.

It does sound like a power-supply issue.

#3 Mon, 10 Aug 2009 - 06:46 68kMLA

What is the history of the Plus? It could be numerous things ...

#4 Mon, 10 Aug 2009 - 09:15 68kMLA

History? eBay!

I had thought power myself. It clearly starts up ok -mostly- so from that I figured that a joint expanding and then failing as it got hotter. As said the ram had been changed to known working and the obvious joints to re-solder have been done I think. I suppose I was wondering if anyone else had experienced anything similar or had an out the box idea.

#5 Tue, 11 Aug 2009 - 02:30 68kMLA

This problem can be caused by several things. Some of the more common are covered in

http://68kmla.org/files/classicmac2.pdf

#6 Tue, 11 Aug 2009 - 06:26 68kMLA

that pdf seems to have info on just my problem. something going wrong with the 5v supply line.

thanks for that.

wheres my fixin' hammer got to...

cheers

#7 Wed, 12 Aug 2009 - 21:44 68kMLA

thank you my happy campers!

it seems that i had dirty contacts at location J4 from the pdf above. weird and simple.

the plus has been running for 40mins - which is 30-35mins longer that it has ever done before.

happy days .

thanks again.

#8 Thu, 13 Aug 2009 - 06:30 68kMLA

And may it work for many, many hours/days/weeks/months/years more!

Congratulations on your persistence!

And if it should start to misbehave again, now that you know the lay of the land, you'll be able to zero in on the problem in no time.

#9 Thu, 13 Aug 2009 - 09:50 68kMLA

i hope so too!