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lackofcolor
January 27th, 2009, 10:39 AM
I have a non-working Macintosh TV and was wondering if anyone who has a lot of computer repair experience could give me a hand either over the forum or even better in person if they live near Omaha, NE.

The Problem:
I have a Performa 550 and I have switched the Mac TV motherboard with the Performa motherboard and the computer will power on. I assume that means the problem is with the Mac TV motherboard. I have changed the PRAM battery as I heard that can make a difference on some Macintosh computers.

I am going to take the motherboard back out and inspect the capacitors to the best of my ability to look for any obvious problems but at the moment that is about the extent of my computer knowledge. I am willing to dismantle the Performa as needed to use for parts on the Mac TV.

If you have any sites with some good information on it or know of any other common problems let me know. Any help would be greatly appreciated.

Thanks.

bguthrie
March 29th, 2009, 08:38 AM
I am a former electronics tech and pretty knowledgeable about the Macintosh's various forms. However, the only tech information I can get is for laptops. Apple does not permit working on their machines (no matter how old) without Apple Certification. I do not have this.

However, it may be possible for me to help with your Performa. I do not understand your reference to a Macintosh TV. Replacement of a motherboard is no mean feat for anyone, considering the possible changes on a motherboard and the lack of firmware updates available from Apple. You might first go back to your original board.

I have many instruments to test parts with (including capacitors) and they may present a look that belies their condition...bulging, for instance, can be a sign for electrolytic capacitors. But electrolytics from old machines often are dried out. I have a test for that, too. Let me know if you are interested still.

tezza
March 29th, 2009, 10:31 AM
But electrolytics from old machines often are dried out. I have a test for that, too. Let me know if you are interested still.

I would certainly be interested in that. I have a Mac SE in the "repair-or-dump" pile whose video is not working. The tube glows at the back so I suspect the verticle video planar. I've done all the usual things (resolder joints etc.) to no avail.

Tez

bguthrie
March 29th, 2009, 03:25 PM
I would certainly be interested in that. I have a Mac SE in the "repair-or-dump" pile whose video is not working. The tube glows at the back so I suspect the verticle video planar. I've done all the usual things (resolder joints etc.) to no avail.

Tez
I assume you are not the January poster but someone who has a Mac SE. Correct?

Yes, I can test electrolytics (the most likely problem for any electronic device that is more than 5 years old), but this may not cure your problem. Is there light on the screen? A single dot or a line? Or is the screen simply solid black/blank?

I live in Southwest Omaha and my email address is bguthrie@cox.net. Let me know what you wish to do.

tezza
March 29th, 2009, 04:55 PM
I posted a thread on my SE Mac a long time ago (http://www.vintage-computer.com/vcforum/showthread.php?t=10053). Since that time it's just been sitting in a corner waiting to be thrown out. I have got a working SE/30 and a couple of classic IIs. I don't really need the SE but...I'd like to know what was wrong with it.

Sorry, I might have mis-interpreted your post earlier on, to read that there is a simple test which we could do, which would reveal a faulty capacitor. You may have meant a test only you could do with special equipment? The SE is not worth enough for me to send you anything from New Zealand, although I appreciate the offer.

I've read that advanced mutlimeters allow testing capacitors by having an extra socket you can plug the capacitor into. Unfortunately my multimeter doesn't have such a feature. ):

Is there any other way to test whether a capacitor is working as it should without this feature?

Tez

bguthrie
March 29th, 2009, 06:35 PM
New Zealand would be a long way for me to travel from Omaha, NE. My wife would dearly love to go to New Zealand and my brother died years ago in New Zealand, but it would be difficult to do. ;)

Anyway, Australia is a hotbed of electronics troubleshooting information and tools. A certain kind of capacitor checker is required to detect the dryness of the electrolyte in the electrolytic capacitor and unless you are into troubleshooting, it might not be worth it, since they are costly. (More than $100 in most cases)

They are called ESR (Equivalent Series Resistance) meters and it takes some hunting to find one for sale.

Good luck; wish I could help.