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max1zzz

IIx Chimes of death

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So I'm trying to figure out what's going on with my IIx, When turned on it it chimes and immediately gives chimes of death. According to apple's troubleshooting guide this is a ram issue

 

What I have done so far is:

Recapped the board

Try with known good ram (Both in all 8 slots and only in bank A, and both 256K sticks and 1M sticks)

Replaced all 8 ram slots (They all had broken clips so needed replacing anyway)

Checked continuity of all 32 data lines from the CPU to the ram slots (As well as the GLU, NuBus, VIA 1, VIA 2, SCC, SCSI chips and the 74 series logic chips by NuBus slot 1 where applicable)

Checked the continuity of all 32 address lines from the CPU to the 74 series logic below the RAM slots (As well as the GLU, NuBus, VIA 1, VIA 2, SCC, SCSI chips and the 74 series logic chips by NuBus slot 1 where applicable)

Checked the continuity of all the address lines from 74 series logic below the RAM slots to the ram slots (through the appropriate resistors which are all the correct value)

Checked the continuity of all the pins of the ram slots to the appropriate pins of the other ram slots (One break was found and repaired, which has not fixed the problem)

Measured all the data lines with the oscilloscope, all had activity (Some had more than others, but none where stuck high or low)

Measured RAS, CAS and R/W with the oscilloscope which all lock fine (Activity on RAS and CAS, R/W is high which I believe is correct as it Mac isn't writing anything to the RAM)

Measured all the address lines with the oscilloscope this is where I am a little unsure, some show activity and some don't, some will show no activity but will if you reset the mac and some only show activity when the mac initially powers on

I have also spent a long time looking over the board for bad traces or via's and there are plenty that look terrible (The board had minor battery leakage), but all that I have tested still have continuity

 

I'm now not sure where to go from here, really expecting to have a broken trace due to the battery damage but I can't seem to find one

 

And advice would be appreciated!

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I'm not the most knowledgable person here (as evidenced by the fact that I keep posting IIx help threads with no replies), but I can suggest something which gave me the crucial info to figure out why my IIx was death chiming when I first got it.  

 

Since in almost, if not all, cases when the IIx death chimes it shows no video, you can't see what's causing the chimes.  But you can using the built-in debug interface, which automatically gets triggered when the Mac plays the chimes.  See this link:  https://mac68k.info/wiki/display/mac68k/Diagnostic+Mode

 

In my case, even though I thought I had checked them all, one of the data lines connecting to the RAM slots was broken; the diagnostic RAM test told me exactly what line it was.  To connect to it, I just used another (working) Mac running ClarisWorks.

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Thanks for the reply the tests look like exactly what i'm looking for however I'm not entirely sure how to interpret the results

For example this is a series of test's I just tried:

*A
*A
*R
0000FFFF0001*R
*4
*4
*000000000
*0
*T000100011100
*T
*R
000000000000*R
*4
*4
*000040000
*0
*T000100011100
*T
*R
000000000000*R
*T000100010001
*T
*R
000000000000*R
*T000300011100
*T
*R
000400000000*R

From what I understand the initially it is saying the boot failed because of a ROM checksum error, All 3 databus tests pass and then the final address bus test fails but i'm not sure how to translate the contents of the diagnostic register into something that will help me pinpoint the fault

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If it's saying the ROM checksum failed then maybe there's a problem with the lines going to the ROM SIMM.  Did you try checking continuity of the pins in the ROM SIMM slot?  Another test you could try would be to swap the ROM with that of another machine that uses a compatible ROM (like the SE/30, IIci, IIcx, IIsi) and seeing if either work.

Edited by tattar8

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15 hours ago, tattar8 said:

But you can using the built-in debug interface, which automatically gets triggered when the Mac plays the chimes.  See this link:  https://mac68k.info/wiki/display/mac68k/Diagnostic+Mode

Wow, why didn't I hear about that yet? Very interesting.

 

Edit - forgot to add:

Is the death chime the slow chimes or the normal death chime?

Only slow chimes indicate a RAM fault of some sort on the 24bit dirty ROMs. Normal death chimes will mean it's something else.

I'd take a look at the address lines going to the ROM as well like @tattar8 already suggested.

One of my Mac IIs had a broken address line between CPU and ROM and it did exactly what your machine does. Startup chime + instant death chimes.

Edited by Bolle

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Yeah I did check continuity to the pins of the rom socket and the all seemed fine, I would try with another rom simm but unfortunately neither my IIci, IIcx or IIsi have simm's

I'm guessing I have a address line problem as the last test I did was the address line test and it did not return all 0's in the diagnostic register but i'm not sure how to interpret what it did return

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Whoops, that already answered part of my edit above.

If you want to see if there is activity on every address line then take the ROM SIMM out and turn the machine on.

The 68030 will cycle through all possible addresses looking for a ROM and you will be able to see if all address lines toggle or if there is something pulling them up or down.

That's also a good way to check if the RAM address muxes as you will have constant changes on their inputs the outputs should toggle at a constant frequency as well.

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Hmm, removing the rom sims results in no activity on any of the address lines

I *think* it is normal death chimes not slow ones, but i'm not sure how fast the normal ones should be so i'm not 100% on that.

 

However, I think I have found the problem, and it is much simpler than I was expecting. It occurred to me that although I don't have another rom simm to try in the IIx I do have other mac's I can try the IIx's rom simm in, In both my IIci and IIcx the rom from the IIx produces chimes of death..... Looks like I just have a bad rom simm.

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Dose anyone know a generic equivalent of the chips on the rom simm? I am trying to read the contents of the chips of the simm to verify if the problem lies with the chips or the simm it's self but I can't get them to read

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Depends on the SIMM. There were a lot of different versions of those around with different chip types.

There is one that has 27C*whatever* compatible mask ROMs. The others are some kind of non-standard pinout ones I think.

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Ahh, i guess this one is a non standard pinout then, Probably explains why I was having trouble finding 1mbit 128kx8 EEPROM's in a PLCC44 package

 

I ended up just probing all the connections on the SIMM, they all check out so I guess it is a bad chip. I have now ordered a ROM-inator II, however as it is going to take a long time to get here I have also ordered some 1mbit EEPROM's in PLCC32 packages which I will be soldering "dead bug" style onto the original SIMM

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Indeed, when I pulled the IIcx out to test the simm it would not chime, after resetting it a couple of times it started working fine (And worked fine on every boot since then). I did try cleaning the simm and slot in the hope it might have just been dirty but no luck

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Well that's disappointing -- the lead ended up going nowhere!

 

If you manually run the ROM checksum test (critical test 4) what does it say?

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New ROM Simm PCB's arrived today

IMG_0922.thumb.JPG.14f7ed6053dafc3f8118c3bc52b1f3cd.JPG

It boots!

Only issue i had is my PCB's are a bit thin, the original simm seemed to be a bit thinner than the normal 1.6mm PCB's so i went for the next size down (1.2mm) but this is too thin to make contact with the slot in the IIx, it dose however make contact with the slot in the IIcx so maybe the one in the IIx is just damaged? either way I fixed it by tinning the contacts on the simm, probably not the most reliable fix long term but it dose the job for now

IMG_0921.thumb.JPG.1024f3f12f592975918dc411de982f9e.JPG

 

I can now finally get on with actually restoring the IIx and maybe actually using it :)

 

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