LC475 SAD MAC Chimes : (

[jajan547]

Hello everyone I have an LC475 motherboard I purchased from Europe the Board has the distinct EURO after the serial number on the board. I bring this up because I am in the US and am having some doubts about things. For starters I have installed a working known good CPU, I have cleaned the board, I have recapped the board, and I have reflowed all on board RAM and the EGRET chip. I also have a brand new PRAM battery. What's weird here is that the computer boots and chimes followed by SAD MAC chimes. I assumed typical PRAM reset would do it but nothing happens. There is no image on screen either, the only way I can physically reboot the computer is by turning it off and then on or by using the CUDA switch to reset it. I will include a video below, any help is greatly appreciated.

 

[jajan547]

Full video HERE.

 

[yock1960]

Did you try to boot this before your rework, at any point? What led you to 'reflow' the RAM and Egret?

 

[jajan547]

Did you try to boot this before your rework, at any point? What led you to 'reflow' the RAM and Egret?

No signs of life and missing solder joints so patched all of that up did PRAM reset and nothing, then I removed all ram chips and one by one added them until I found one that had the sad mac chime, so I swapped in this chip KM44C1000CJ-7 in place of the original nec 424400-80, I hope it’s compatible? But seems to boot kinda.

 

[yock1960]

No signs of life and missing solder joints so patched all of that up did PRAM reset and nothing, then I removed all ram chips and one by one added them until I found one that had the sad mac chime, so I swapped in this chip KM44C1000CJ-7 in place of the original nec 424400-80, I hope it’s compatible? But seems to boot kinda.

I would have thought that it wouldn't work at all without the complete set installed.

 

[jajan547]

Oh I see so all on board RAM has to match, I removed this added chip and it boots just fine with 7 of the 8 RAM chips so that's cool, obviously some applications are now drastically slower such as startup and restart/power off.

 

[yock1960]

Oh I see so all on board RAM has to match, I removed this added chip and it boots just fine with 7 of the 8 RAM chips so that's cool, obviously some applications are now drastically slower such as startup and restart/power off.

Well that's progress! Actually, what I meant was that it surprises me that you even get any chime without a complete set of 8 chips, whether or not it's a matched set. So, apparently that chip isn't quite compatible, perhaps the timing mismatch is a problem within this 'bank' of RAM. Perhaps someone with more expertise will chime in!

Good luck!

 

[Kai Robinson]

The chip you've used should be fine - it's rated for 70ns, instead of the 80ns stuff on the board. You can use this chart to cross reference the chips:

Memory Chip Conversion Chart

ardent-tool.com

 

[jajan547]

The chip you've used should be fine - it's rated for 70ns, instead of the 80ns stuff on the board. You can use this chart to cross reference the chips:

Memory Chip Conversion Chart

ardent-tool.com

Thank you it works but still won’t boot up without extra ram simm, and by boot up I mean chimes no problem but no video unless the ram (not vram) simm is in. Also when it boots there are no problems I only run into issues when I choose shut down or restart as the computer just freezes, this is super weird, any ideas.

 

[yock1960]

The memory chips are 1Mx4, 8 chips makes for a total of 4 megabytes. With 1 chip removed, you're missing 1M bits from that 4 megabytes. If you run any of the memory checking utilities, Snooper say...it would show bad memory. Either that chip is bad somehow, or the soldering was perhaps not good. You could try soldering it back in, or try a different chip. Another possibility is that there is some other problem on the board. Did the old caps leak? Was there corrosion?

 

[jajan547]

The memory chips are 1Mx4, 8 chips makes for a total of 4 megabytes. With 1 chip removed, you're missing 1M bits from that 4 megabytes. If you run any of the memory checking utilities, Snooper say...it would show bad memory. Either that chip is bad somehow, or the soldering was perhaps not good. You could try soldering it back in, or try a different chip. Another possibility is that there is some other problem on the board. Did the old caps leak? Was there corrosion?

Old caps leaked resoldered all ram chips it boots fine but lags like I said above still

 

[jajan547]

Old caps leaked resoldered all ram chips it boots fine but lags like I said above still

So like shutdown and restart in the control panel freezes and locks up the system, this is so bizarre.