Performa 476

[NickNick]

Morning all.

So recently dug out the Macs again and as always one gives issues. Another 476 is exhibiting the same exact symptoms as another LC 475 I have. They both start up give happy bong, then chimes of death. Both of them do the exact thing. Its always the 475's - 6's it seems like. Anyone else ever have issues like this with Mac's? I really don't know what to check. I have recapped the boards and they initially both worked for some time, stored them took them out and no go. They are not stored in boxes, they are stored in a spare closet in my house. Temperature controlled.

These are my favorite style machine, the pizza boxes; I want these fixed. I cant seem to throw them away.

Any info would be awesome!

Thanks so much.

 

[Floofies]

What kind of hard drives are in them?

 

[Quadra]

My first computer was a Performa 475 in 1995. After a couple of years it began to shut down after a while. With the top removed, it kept going for longer. Later I got the chimes of death and threw it away. That case didn`t cool a 68LC040 enough I suppose. 

 

[Macdrone]

Caps caps caps...... 

Capacitors need replaced.

 

[Floofies]

But Macdrone, he says they have been recapped!

 

[NickNick]

Hi there and thank you for the replies.

The HDD's were Quantums one being the 230 meg ones which suck as that MB size seem to just stop working as I now have two 230  megs that just stopped working. Tried booting the machines with no HDD's in there either. Tried the no memory thing too.

I had heat sinks on the processor. I do feel the 040's get a tad hot. Literally it worked last time I used it which was like four months ago. I have two of these machines that do the exact thing. I have no idea what to look for. The MoBo's look fine to me I don't see any burned areas or anything else weird. Any one know of any chip that fails on these machines?

The machines have been recapped.

 

[MJ313]

Did you recap it yourself? Was the board cleaned well? Two of the caps live right near the onboard ram, so goo might've gotten into that chip. Try easy stuff first...

1. remove any extra ram and try and boot it.

2. How's the pram? Are they original? 475's won't have display without a working PRAM battery, but it's worth yanking it and seeing if you get chimes of death.

3. Wash the board thoroughly. Maybe it wasn't washed well, dry it out completely and try again.

 

[MJ313]

Just found your other thread. Looks like you have waged this battle before. All the same troubleshooting applies, I'm afraid. 

https://68kmla.org/forums/index.php?/topic/22646-performa-475-chimes-of-death/

 

[NickNick]

I have, but find it really odd that the exact same thing is happening. There has to be something amiss on the MoBo. I guess I'm trying to figure out what it's testing. Something is not passing a test. Someone has to know what the machines check when they do the power on tests. I have yet to be able to pin point what these machines are testing when they power on.

 

[beachycove]

http://myoldmac.net/FAQ/MacintoshTroubleshootingStartUp.htm

https://web.archive.org/web/20090113083629/http://support.apple.com/kb/TA46376?viewlocale=en_US

These may be some help.

There was an excellent summary written up by someone on here years ago (equill maybe?), so you could try a search.

 

[beachycove]

And this

http://www.retrocomputing.net/info/siti/apple_repair/www.whoopis.com/computer_repair/Theories_of_Operation/Early_Mac_Theory.pdf

Dated but probably still usable.

 

[NickNick]

Thank you so very much. That was incredibly helpful.

Still trouble shooting the computers. No luck so far, I wonder if the processors went out on the computers.

 

[NickNick]

So after reading through I'm thinking it has something to do with memory mapping. 

Not to sure about memory mapping and what it all entails. I read up on it and to me it seems like its going between ROM and RAM for the mapping. Somewhere during that process I think the computer is failing causing the computer to not boot up. I'm just guessing here but form what I read it seems as it tests mostly memory. THe chips and other IC's are tested up on immediate start up but memory is after. And the mapping is after the happy chime. 

Also, someone else noted that the motorola chip generator for the 040 goes bad at times. Anyone know if this would cause bad chimes upon start up of after the good start up chime.