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 PostPost subject: Help with my Classic II        Posted: Sun Mar 09, 2008 9:29 pm 
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Hey!
I've got a Macintosh Classic II with System 7.5.5 on it.
It sometimes won't boot. Not even the boot sound after the POST.
Look, this is the way it stays, and I don't know why. It's just a random thing, and I would like to have some help on solving the problem. Thanks!
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 PostPost subject:        Posted: Sun Mar 09, 2008 10:19 pm 
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It's called "jail bars", a common problem with old "compact Macs" - try searching Google for Mac jailbars/jail bars, I found this which seems to be quite a good summary of possible solutions. Capacitor leakage is a common problem on these older machines - cleaning the motherboard of the stuff that has leaked out of the capacitors will fix it for a while but they will leak again so replacing the capacitors is the only permanent fix for that, but that would be very difficult to do unless you're extremely skilled with electronics.

Removing, cleaning any dirt from the connectors and reinserting the memory and Mac ROM (the other thing they suggest there) would be the first thing to try, as would perhaps a new battery (they do mention that there too thought to be honest I doubt that would cause it - you know you have a dead battery if the clock resets to a past date if you unplug the machine). Also try with the Ram SIMMs removed and just using the built-in memory, in case they are bad.


WARNING: do NOT open up this machine if you do not know what you are doing, as it contains a CRT screen it could give you a very nasty electric shock! (CRTs keep a high voltage charge even when turned off and unplugged) The Apple Service Source manual (I have these if you want it, they tend to be hard to find online as they are copyrighted and meant for Apple authorised service providers only, and Apple demand they are taken down if they find them on websites) will guide you through opening the machine and removing the various parts, as well as warn you of the dangers.

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 PostPost subject:        Posted: Sun Mar 09, 2008 11:27 pm 
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Vista Ultimate R2 wrote:
It's called "jail bars", a common problem with old "compact Macs" - try searching Google for Mac jailbars/jail bars, I found this which seems to be quite a good summary of possible solutions. Capacitor leakage is a common problem on these older machines - cleaning the motherboard of the stuff that has leaked out of the capacitors will fix it for a while but they will leak again so replacing the capacitors is the only permanent fix for that, but that would be very difficult to do unless you're extremely skilled with electronics.

Removing, cleaning any dirt from the connectors and reinserting the memory and Mac ROM (the other thing they suggest there) would be the first thing to try, as would perhaps a new battery (they do mention that there too thought to be honest I doubt that would cause it - you know you have a dead battery if the clock resets to a past date if you unplug the machine). Also try with the Ram SIMMs removed and just using the built-in memory, in case they are bad.


WARNING: do NOT open up this machine if you do not know what you are doing, as it contains a CRT screen it could give you a very nasty electric shock! (CRTs keep a high voltage charge even when turned off and unplugged) The Apple Service Source manual (I have these if you want it, they tend to be hard to find online as they are copyrighted and meant for Apple authorised service providers only, and Apple demand they are taken down if they find them on websites) will guide you through opening the machine and removing the various parts, as well as warn you of the dangers.

Thanks a lot for the tips. I've got an expert friend on the matter (Electronics), So I'll do as you tell me.
I do would appreciate a copy of the Service Manual, thought. I'm going to fix it with him. I think that it might just be dust, because sometimes it works perfectly. Thank you very much!! :D


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 PostPost subject:        Posted: Mon Mar 10, 2008 12:10 am 
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I've put it here for you, hope it's useful. Please be careful if you do decide to open up the machine though, I don't want you killing yourself! :) Whatever you do, don't touch the CRT inside (they are very fragile in addition to dangerous). Some people say a safe way to open these machines is to pull the plug out (as opposed to switching it off using the power switch) while it is on with the screen turned up to full brightness as this is supposed to remove the charge from the CRT that otherwise remains even after it's turned off, but I can't confirm whether or not this is true.

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 PostPost subject:        Posted: Mon Mar 10, 2008 2:42 am 
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Vista Ultimate R2 wrote:
I've put it here for you, hope it's useful. Please be careful if you do decide to open up the machine though, I don't want you killing yourself! :)

Oh, I know that! LOL
My friend and I got some special Gloves for high voltage handling, so np. Thanks!!


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 PostPost subject:        Posted: Mon Mar 10, 2008 10:23 am 
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Vista Ultimate R2 wrote:
<SNIP>


WARNING: do NOT open up this machine if you do not know what you are doing, as it contains a CRT screen it could give you a very nasty electric shock! (CRTs keep a high voltage charge even when turned off and unplugged) The Apple Service Source manual (I have these if you want it, they tend to be hard to find online as they are copyrighted and meant for Apple authorised service providers only, and Apple demand they are taken down if they find them on websites) will guide you through opening the machine and removing the various parts, as well as warn you of the dangers.


CRT screens can hold up to a few million volts.
If you get an serious shock, most likely it will kill you.

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 PostPost subject:        Posted: Mon Mar 10, 2008 5:27 pm 
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DjRob wrote:
Vista Ultimate R2 wrote:
<SNIP>


WARNING: do NOT open up this machine if you do not know what you are doing, as it contains a CRT screen it could give you a very nasty electric shock! (CRTs keep a high voltage charge even when turned off and unplugged) The Apple Service Source manual (I have these if you want it, they tend to be hard to find online as they are copyrighted and meant for Apple authorised service providers only, and Apple demand they are taken down if they find them on websites) will guide you through opening the machine and removing the various parts, as well as warn you of the dangers.


CRT screens can hold up to a few million volts.
If you get an serious shock, most likely it will kill you.


Yeah, thanks!
Yesterday we made some research and there are a bunch of guys we know who work fixing CRTs, they are going to help us discharge it completely before any manipulation.


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