Editing Macintosh SE/30 Troubleshooting (section)

== Minimal Boot Requirements ==
If you have a major issue like no bus activity, no boot sound, or even no AV out, it is best to start with the absolute minimal boot, and look for the address bus toggling constantly on power up, or the initial boot audio chime.

=== Critical ICs ===
The initial startup is done by the Glue Logic chip UI8. I have not fully reverse-engineered its boot-up yet but have found all required chips.

The following ICs are critical for the boot operation of the system to get to the out of reset address toggling state.

* 68030 CPU (UK8)
* Glue Logic (UI8)
* PAL for RAM Signals (UH7)
* PAL for 68k/Video Signals (UI6)
* Resistor Packs for Pull-Ups (RP7 / RP9)
* Sound IC (UE10)
* ROM (J14) if you want to hear boot sounds, if not oscilloscope for address bus activity
To boot from only 5V you want to remove the sound chips too and with up the headphone port so you can still hear audio from the headphones:
[[File:SE-30 5v Power Bridge.png|thumb|312x312px|SE/30 5v Power Bridge]]
* Remove UB10 / UB11
* Jumper between UB11 pins 8 and 9 to short together analog and digital grounds (audio will be a little noisy). This also makes the S2 NMI button work again as once UB11 is removed the analog and digital grounds are separated and the reset button uses the disconnected ground.   '''''NOTE: S1 normal reset button won't work with UB10 removed as it is responsible for sensing that button and pulling reset low. So use S2 or disconnect power to reset.'''''

=== Non-Essential ICs ===
You can remove all non-essential chips in case them failing pulls voltage rails or lines bad if you are still struggling to diagnose:

* UD1
* UK4 (RTC)
* UD12 / UE12 / UG12 / UI12
* UK12 / UJ11 / UK11 / UL11
* UI5 (FPU)
* All RAM (Because if it successfully checks RAM but UG12/UI12 or UJ11 fail or are missing you won't hear any beep and get horizontal lines)
* UK6 (Video IC)
* UE6 / UG6 / UE7 / UG7 (PALs)
* UC6 / UC7 (Video RAM)
* UA8 / UB8 / UC8 / UD8 / UE8 / UF8 / UG8
* UI2 / UJ2 / UI3 / UJ3 / UJ4 / UI4 / UJ6 (Logic)
* RP1 / RP4 / RP5 / RP6 / RP8 (Resistor packs)

=== Expected Boot ===
With just the critical ICs installed, if you have also removed the sound chip and bridged the audio jack (otherwise if not you will need 12V power applied also) you should expect to hear a sad mac boot sound when power is applied.

If you have no ROM, instead you can probe the lower address pins of the ROM socket and they should be constantly pulsing.

If you do not see this, perhaps check all the following chips happy to come out of reset:

* In/Out 68030 ('''UK8''') !RESET
* VIA1 ('''UK12''') pin 37
* VIA2 ('''UK11''') pin 37
* Apple Desktop Bus ADB Chip ('''UL11''') pin 4 (for keyboard/mouse)
* Super Woz Integrated Machine SWIM ('''UJ11''') pin 25 (for floppy drive)
* 53C80 SCSI Controller ('''UI12''') pin 7 (for HDD)
* ASC stereo sound chip ('''UE10''') pin 40
* Sony Sound Chip ('''UB11''') pin 5