Macintosh IIx - Immediate death chime, no video

[Johnnya101]

Sent my board out to Amiga of Rochester to get repaired and recapped. Upon recapping, Thomas discovered that it powers up with an immediate death chime and no video.

He sees nothing obvious bad, and has repaired any broken traces.

I have read on here no video upon death chime is usually caused by the death chime itself. I am thinking the ram can be ruled out, as the death chime is immediate. Maybe bad rom?

Anything sound like it could be the culprit off hand? I can relay any tips here to him, or maybe he will pop in here with more details. I'll update if he figures out what it was, maybe it will help someone down the road.

 

[joshc]

Bad RAM sockets or bad RAM. With no RAM, you will get death chimes. So if none of the RAM is seated correctly, you get death chimes. I had thick pieces of cardboard in-between the RAM modules on my IIx, otherwise it wouldn't work properly. That's where I'd start, rule that out first. The RAM has to be tightly seated.

 

[Johnnya101]

Ok, I'll let him know to check that. They are original modules and the thing has never been turned on in 20 years, so maybe they are bad as well.

 

[pezter22]

There is a great resource with a book called "Troubleshooting_Your_Macintosh_1992" that lists the POST sequence.
I am having a similar issue with my MacIIfx with an immediate death chime. My RAM is good and I recently purchased a ROMinator that bypasses the RAM check at startup and still I get a death chime.

From the listing in the book, I will be checking number 3 on the list and check the traces with he Sony sound chips which is also associated with the NMI button (Reset & Interrupt buttons). So I will continue to figure out this rabbit hole...

https://vintageapple.org/macbooks/pdf/Troubleshooting_Your_Macintosh_1992.pdf

From Page 100
A typical Macintosh hardware initialization consists of the following events:
1. Power is applied to the system.
2. The power supply establishes the appropriate voltage levels required by
the system.
3. These voltage levels typically are monitored by one of the Sony sound inte-
grated circuits on the logic board. If the levels are acceptable, a reset sig-
nal is then generated by this IC.
4. This reset signal forces the central processing unit (CPU), math coproces-
sor (FPU), primary logic ICs, expansion cards, and other internal devices
to come to a known state.
5. The reset signal is withdrawn.
6. The CPU obtains the reset vector (typically four eight-bit words), which
begins at memory address 0000 0000 (hexadecimal). A ROM overlay
address map then is used by the memory decode and control circuitry to
map the standard memory locations to a ROM address. The CPU goes to
the reset vector memory address, which is now mapped to ROM.
7. Special program code called the Macintosh reset handler (MRH) is exe-
cuted. The MRH remaps ROM and RAM to their respective locations.
8. The MRH initiates the P.O.S.T. sequence.
If your Macintosh fails any portion of the initialization, it appears to be dead.
Refer to the general troubleshooting portion of this book for possible remedies.

 

[Johnnya101]

To finally end this, joshc was right. There were a couple bad ram slots. All good now!