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| Broken Performa 475 |
Posted by: JP_2208 on 2022-05-01 02:43:13
Last year i bought a Performa 475 of of ebay that was listed as not working. As it wouldn't start at all I first recapped the power supply and after that it did turn on, but didn't do anything besides the eight tone chime of death with a black screen. My next suspect were the caps on the logic board so I replaced all of them but still nothing happens, no screen, no activity on the floppy drive, only the eight tones. I also tried it with all the RAM modules removed but that didn't help either. Any ideas what else it might be and what I could look at? As far I'm aware the eight tone chime just means general hardware failiure so at the moment I've reached a dead end. |
Posted by: joshc on 2022-05-01 06:18:06
Tried with a new PRAM battery yet? It needs a good one providing >3V to for a chime/video.
Checked voltages at the power supply connector? 12v and 5v need to be within acceptable tolerances. |
Posted by: JP_2208 on 2022-05-01 07:24:35
It didn't come with a PRAM battery however I bought a new one. Checking the voltages at the connector isn't even something I thought about until now. Going to give it a try. |
Posted by: SpocksBeer on 2022-05-02 19:00:49
475 needs a PRAM battery to work. Will just chime and black screen without one.
Alternatively you can quickly turn it off and on again and 9 times out of 10 it'll boot without a PRAM battery. |
Posted by: JP_2208 on 2022-05-02 22:51:30
Yeah on topic of that. I've heard that sometimes even if you have a battery the PRAM needs to be reset. How do I do that? I only know its got something to do with the keyboard. |
Posted by: JP_2208 on 2022-05-02 22:53:18
I am only just realizing that the logic board recap might have been completely unnecessary the more i think about all of this |
Posted by: volvo242gt on 2022-05-03 00:22:23
Yeah on topic of that. I've heard that sometimes even if you have a battery the PRAM needs to be reset. How do I do that? I only know its got something to do with the keyboard. Command-Option-P-R is the keystroke. Hold the keys down at boot. It'll do the first chime, then do another. |
Posted by: joshc on 2022-05-03 03:08:56
I am only just realizing that the logic board recap might have been completely unnecessary the more i think about all of this No it should be done on these, I've had a few 475s with leaking logicboard caps. |
Posted by: Ajediday on 2022-05-03 07:08:13
This has me thinking about the issues I am having with my 475. I started out with the start then death chimes, after reflowing and making sure two of the ram chips were making connection as they should, I am getting just start up chimes, no video. I remember attempting the Command-Option-P-R, but I don't remember it working (the computer didn't chime again). I need to confirm it when I get a chance today |
Posted by: jajan547 on 2022-05-03 10:29:35
This has me thinking about the issues I am having with my 475. I started out with the start then death chimes, after reflowing and making sure two of the ram chips were making connection as they should, I am getting just start up chimes, no video. I remember attempting the Command-Option-P-R, but I don't remember it working (the computer didn't chime again). I need to confirm it when I get a chance today Same issue try adding a RAM Simm on top of the VRAM that did it for me |
Posted by: Ajediday on 2022-05-03 11:45:54
Well right now it isn't giving me anything, Saturday it at least gave me a chime. Going to have to go over it again and see if anything is shorting or what.
Update:
Reseated things, back to starting chimes. Tried several times and the Command-Option-P-R does nothing on my 475, on the 450, I get the expected chime again with the same keyboard. This is leading me down the road of something up with egret and anything else that might work with ADB |
Posted by: joshc on 2022-05-03 23:35:35
Get a good 3.6V battery in there first before doing any more diagnosis. |
Posted by: Ajediday on 2022-05-04 01:15:43
I am using a fresh battery that is good, works fine in the 450. |
Posted by: joshc on 2022-05-04 01:22:31
@Ajediday Sorry I got confused, thought you were the OP. Might be worth starting your own thread as your issue is probably different than the OP's?
No video on a 475 that chimes OK and has a good battery and good PSU is probably an Egret issue. |
Posted by: JP_2208 on 2022-05-14 01:55:21
Took a while (i had to aquire a keyboard first) but it doesnt seem to change anything. I still only get the chime even when holding down the keys. also the chime happens basically immediatly after the "bong" and theres also no activity on the floppy drive when i put a boot disc in (the computer is missing the hd) |
Posted by: JP_2208 on 2022-05-14 02:04:36
Heres a video of it "starting" if that helps with any diagnosis
View attachment 20220514_105832[1].mp4 |
Posted by: jajan547 on 2022-05-14 06:57:29
Heres a video of it "starting" if that helps with any diagnosis
View attachment 41709 Looks like a bad RAM chip on board try removing and cleaning the pads under the two closest to C128 and C127 |
Posted by: JP_2208 on 2022-05-15 05:31:32
I have to admit that won't be easy as i do not have the steadiest hands or best soldering equipment however i'll at least give it a try. Are we talking about just taking them of, cleaning and putting them back or is it full on replacing the chips? |
Posted by: jajan547 on 2022-05-15 10:37:04
I have to admit that won't be easy as i do not have the steadiest hands or best soldering equipment however i'll at least give it a try. Are we talking about just taking them of, cleaning and putting them back or is it full on replacing the chips? No so take one off then turn on machine if you hear death chimes still that’s not the one so you put it back keep repeating until death chimes go away when they go away you know you’ve found the bad chip. |
Posted by: JP_2208 on 2022-05-20 07:03:07
there isn't by chance any way to test the chips without taking them off is there? |
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