Macintosh IIsi Magic chime sound. What does it mean?

[zezba9000]

Made some directions for making a Macintosh IISI PSU very quickly. Based on a YouTube video but simplified.

1) First buy one of these "24 Pin to 10 Pin" off Amazon or Ebay: https://www.amazon.com/gp/product/B07C5P5H2L

2) Rewire it with the image below.

More info and reference files: https://1drv.ms/u/s!Alt5wRhQYKD7gd4qoWijVukp9uDeOg

YouTube video this is based on: https://www.youtube.com/watch?v=CNerj2mQ4vw

 

[zezba9000]

Did a quick clean of the new motherboard. Everything works except for the scsi. I know the hard drive and cable are fine as it came from a working computer.

Might need to replace the caps if thats the issue.

 

[zezba9000]

Also just a tip. If you need to convert an ATX 20-pin to a 10-pin you can also just use a PICO PSU to embed the PSU directly into the Macintosh computer as they're super small.

Something like this would work: https://www.ebay.com/itm/12V-180W-DC-Pico-ATX-switch-PSU-with-Power-Adapter-Car-Auto-MINI-ITX-Power/263087650726

For a CPU heat-sink, get the same ones used for ARM A20 (they're the perfect size [tested]): https://www.ebay.com/itm/Heatsink-for-Cubieboard1-Allwinner-A10-Cubietruck-Cubieboard2-A20-heat-sink/231904141192

 

[9166188]

@zezba9000

You got very useful details to use an ATX PSU.  Good job!

It's nice that we can rule out any ROM SIMM issue and focus on other possibilities.   Your new working motherboard will be really useful for comparison.

My board looks the same as your new one with onboard ROMs (these ROMs sit between the power connector and CPU) except that it does not work and my memory slots are white, not black.  So, I guess the color (whether black or white) has nothing to do with whether the make needs a ROM SIMM or not.

Some thoughts on your thinking:

#1 No harm you give it a try and rule out any cap being a culprit.  I replaced all caps and washed the board multiple times.  That did not improve anything. 

#2 I can confirm that like yours my 68030 CPU is hot relative to other chips which are about body temperature.   So, the temperature of the CPU stands out.  Having said that, it's only about as hot as a hot coffee mug which I can still touch comfortably.  In other words, it is not burning nor too high to give me concern.  

#3 In any case, it's strange that it is much hotter than other chips.  What is it doing?  Unlikely in a infinite loop of calculations.   I don't know whether this temperature is 'normal' for IIsi system when they are running idle w/o any OS.  Can the board still play chime of death music when the oscillator is faulty?  If yes, your suspicion over the oscillator can be a good one.  There is a post about upgrading IIsi clock speed which means the oscillator can be replaced.

The fact that my IIsi gives a chime of death shows it is able to do some early stage diagnostic.  But it immediately finds very fundamental failure(s) and simply gives up before it even shows any sad Mac icon on screen.  It looks to me like it got stuck before it can move on to check ROM, memory, SCSI and other subsystems.   What does it find? 

http://educ.jmu.edu/~jarvislb/utils/macintosh/boot2.htm

 

[zezba9000]

@zezba9000

You got very useful details to use an ATX PSU.  Good job!

It's nice that we can rule out any ROM SIMM issue and focus on other possibilities.   Your new working motherboard will be really useful for comparison.

My board looks the same as your new one with onboard ROMs (these ROMs sit between the power connector and CPU) except that it does not work and my memory slots are white, not black.................

#1 I ruled out buy connecting the caps from the working board to the non-working one with some wire clamps.

The CPU being as hot as it is is going to be fine when idle. Under load for a long period of time it may not be (as is the case with ARM chips in your phone etc). My concern is these computers have been around for a very long time and the one I got that doesn't work was very dusty which can increase the CPU temperature even more and if someone left it on under stress for a long time it could cause damage as these old computers don't have auto power off when the CPU gets to hot (if you get yours working again, I would put a heat-sink on it). When a CPU goes bad it can still partially work but then fail when it starts to use other parts as not all circuits will just stop functioning.

The other possibility is the original PSUs in these damage something else on the motherboard. Both PSUs in the working and non-working IISI computers were leaking some fluid on the board and both PSUs had issues. If the original PSUs were this bad, maybe a bad CAP in them caused a bad power fluctuation on the motherboard and damaged a chip when going out. My hope is it damaged the CPUs crystal oscillator and the reason I think I could be on the right track is the CPU in the bad computer gets much hotter much faster than my working one.

I'm moving soon, so my on and off tests with this may slow for a month or couple of weeks. Just FYI.

 

[zezba9000]

A long overdue update.

My bad motherboard still has the bad chime sound after replacing its 40mhz crystal oscillator.

My good motherboard (besides the SCSI not working [so it boots from the Mac ROM-inator II]) I replaced with a PICO PSU I shoved in the original PSU metal box. So now its powered with a 90W / 12v laptop power supply.

Custom ROM SIMM used: https://www.bigmessowires.com/mac-rom-inator-ii/

I bought this 20pin one but any 24pin one should work as well: https://www.amazon.com/gp/product/B07H5FP5KY/

A power brick like this works with it: https://www.amazon.com/gp/product/B076C7X7GW/

Because my old mac tube screen is going out I got a "HD15 VGA Monitor Female to DB15 MAC Male Converter Adapter".

You can buy those here: https://www.ebay.com/itm/HD15-VGA-Monitor-Female-to-DB15-MAC-Male-Converter-Adapter-w-Dip-Switches/271137033572

For Macintosh IISI you only need switch 6 and 8 on.

Switch reference download link: https://1drv.ms/b/s!Alt5wRhQYKD7geVqezziWWeKRZ5-hg

 

[zezba9000]

Also here is a picture of the heatsink I used on the CPU. Just some extra love.

 

[zezba9000]

Update. I ended up having issues with PICO PSU's even a 300w one. Maybe the caps don't hold enough juice but only my 500w standard ATX PSU keeps the computer 100% stable all the time.

Even a 250w 80 PLUS Bronze Certified ITX PSU has stability issues after a while: https://www.amazon.com/gp/product/B006ORBC14

Sadly I will have to keep the 500w PSU external from my computer.

Maybe someone has a good idea of why only the 500w psu is the only one that works well?

EDIT: After more testing even the 500w the computer will eventually crash running a screen saver. O well at least its stable enough for what I need it for.

 

[olePigeon]

You should really recap that IIsi.  Save your money on the PSUs and get yourself some caps.

 

[zezba9000]

You should really recap that IIsi.  Save your money on the PSUs and get yourself some caps.

I already recapped it.

 

[olePigeon]

Oh, my mistake.  Pictures looked like the old caps.

Don't suppose you have a Snooper card?  It could tell you which (if any) of your power rails aren't up to snuff.  Although I think you've ruled out power supplies, so I honestly don't know.

 

[barrakuda]

Hello, I'm dealing with this same issue on my Mac IIsi. I did a complete re-cap of the motherboard and PSU, but I'm still getting the death chime right after the regular chime. Please let's not give up! We have to get these machines working!

 

[9166188]

Hello, I'm dealing with this same issue on my Mac IIsi. I did a complete re-cap of the motherboard and PSU, but I'm still getting the death chime right after the regular chime. Please let's not give up! We have to get these machines working!

Yes, I got two IIsi.  Both have exactly the same "chime of death" problem.  It seems unlikely to be a coincidence.   Their root cause must be the same.  Wish someone can triangulate the culprit from these discussion which at the moment is hitting a wall.   We need a Sherlock Holmes.

 

[9166188]

Update. I ended up having issues with PICO PSU's even a 300w one. Maybe the caps don't hold enough juice but only my 500w standard ATX PSU keeps the computer 100% stable all the time.

Even a 250w 80 PLUS Bronze Certified ITX PSU has stability issues after a while: https://www.amazon.com/gp/product/B006ORBC14

Sadly I will have to keep the 500w PSU external from my computer.

Maybe someone has a good idea of why only the 500w psu is the only one that works well?

EDIT: After more testing even the 500w the computer will eventually crash running a screen saver. O well at least its stable enough for what I need it for.

Also, good to hear from zezba9000.  Congrats on the progress in the PSU experiment -- very educational!

 

[ktkm]

Hello, I'm dealing with this same issue on my Mac IIsi. I did a complete re-cap of the motherboard and PSU, but I'm still getting the death chime right after the regular chime. Please let's not give up! We have to get these machines working!

Same issue here as well … I even re-capped the daughter card in the psu and it looked well, but a couple of weeks later it started to kill the fuse …

 

[zezba9000]

Hello, I'm dealing with this same issue on my Mac IIsi. I did a complete re-cap of the motherboard and PSU, but I'm still getting the death chime right after the regular chime. Please let's not give up! We have to get these machines working!

What would be really useful is to rule out a bad CPU or RAM (more likely on-board RAM). My guess is those crap PSU's that came with these caused some kind of stress somewhere.

Another observation is my motherboard that does work has a non-working SCSI. Even re-cap didn't fix that. You also notice how the SCSI drives on these were powered through the board? I wonder if a power stress issue exists in that area. Maybe some kind of power short. Because there are so many people with the same sounding issue figures crossed it a fixable issue.

My first/next suggestion would be for someone to replace the on-board memory. My board that doesn't work didn't have the best looking modules. Also when there is a bad PSU for long periods of time... ram can get damaged (pretty common I think).

Memory on the board is "TI TMS44C256DJ" which can be bought here: https://www.ebay.com/itm/TI-TMS44C256DJ-Dynamic-RAM-Fast-Page-256Kx4-26-Pin-SOJ-New-Quantity-5/251812621170?epid=1863064326&hash=item3aa133ab72:g:0AkAAOSw-W5Uym1J

If anyone has a bad board with some better soldering equipment for this kind of job you should give it a shot. I'll buy the ram but this requires a better soldering skill and equipment than I have.

 

[ktkm]

My first/next suggestion would be for someone to replace the on-board memory. My board that doesn't work didn't have the best looking modules. Also when there is a bad PSU for long periods of time... ram can get damaged (pretty common I think).

The on-board memory is what I would like to rule out as well, now that the PSU has been restored to working condition again. But just like you mention, my soldering skill also lacks at this point.

 

[9166188]

The on-board memory is what I would like to rule out as well, now that the PSU has been restored to working condition again. But just like you mention, my soldering skill also lacks at this point.

(1) The onboard memory is also what I suspect could be the culprit but it is difficult to verify.  (2) The display chip can be a suspect since it displays nothing other than blank/blue screen.  (3) A broken wire somewhere onboard is likely but so far I cannot find any broken trace. 

I think we can confidently rule out the PSU.  Mine has been recapped but nothing changed.   SCSI as a culprit cannot be ruled out but unlikely.  If it is SCSI, the system should still boot to a sad Mac icon.   SCSI is not critical enough to fail the bootstrap so early.

Since it cannot even show a sad Mac icon, the failure must be very fundamental.    

 

[elemenoh]

I had this same issue with a IIsi. Recapped and death chimes afterwards with a known-good PSU.

I ran TechStep diagnostics and sure enough:
MacIIsi RAM size: 0 MB? LgcBdRAM: BAD SIMMS: | | | |

The chips on this MLB are Samsung KM44C258J-8 256K x 4-bit in a SOJ-26/20 package.

I had a spare 1MB stick of RAM with 8x Hynix HY531000J-80's, so used those to replace all of the onboard RAM. I now get a regular chime, but no video and still get the onboard RAM failure on the TechStep. So I have a bad joint, trace or other component in the RAM circuit to hunt down.

 

[imactheknife]

My iisi was giving me the death chime. I had to fill the 4 slots with exact same ram and she is fine now.. before that, any ram combination i put it in gave me the chime and no video.

 

[JC8080]

I had this same issue with a IIsi. Recapped and death chimes afterwards with a known-good PSU.

I ran TechStep diagnostics and sure enough:
MacIIsi RAM size: 0 MB? LgcBdRAM: BAD SIMMS: | | | |

The chips on this MLB are Samsung KM44C258J-8 256K x 4-bit in a SOJ-26/20 package.

I had a spare 1MB stick of RAM with 8x Hynix HY531000J-80's, so used those to replace all of the onboard RAM. I now get a regular chime, but no video and still get the onboard RAM failure on the TechStep. So I have a bad joint, trace or other component in the RAM circuit to hunt down.

Do you think the replacement chips need to be 80ns? The IIsi needs min 100ns, but I wonder if the onboard chips need to be faster because they are also used for video RAM. I'm asking because I have some 1mb 100ns SIMMs around and I am thinking of replacing the onboard chips to see if it fixes my death chime.