Power Macintosh 7200/90 screen goes black half way booting

[Jon183]

The 7200/90 came with OS 9.2 which isn't officially supported, once the loading bar reached half way, screen just went black.

So far I replaced the PRAM battery which happened after this issue occurred.

System appears to have 128MB RAM, boots off its normal HDD, CD Drive, floppy and no expansion cards or extra VRAM DIMMs.

I also use a DB-15 to VGA connector set to 23567.

 

[Zippy Zapp]

Can you boot off a CD to use disk first aid?  I tried 9.1 on my 7200/90 and it seemed very sluggish. 

You replaced the PRAM battery and I think on these Macs you need to reset the Cuda chip.  There is a small button on the motherboard that resets the chip.  Do a search for the 7200 service source manual to learn how.  That may get it going again...

The cuda reset button is right above the PCI slots.

I copied the relevant bits from the manual:
 

The Cuda Chip
The Cuda is a microcontroller chip. Its function is to • Turn system power on and off
• Manage system resets from various commands
• Maintain parameter RAM (PRAM)
• Manage the Apple Desktop Bus (ADB) • Manage the real-time clock
Many system problems can be resolved by resetting the Cuda chip (see Symptom Charts for examples). Press the Cuda reset button on the logic board to reset the Cuda chip. (See "Logic Board Diagram" later in this chapter to locate the Cuda reset button.) If you continue to experience system problems, refer to "Resetting the Logic Board" later in this Basics chapter.
 
Resetting the Logic Board
Resetting the logic board can resolve many system problems (refer to "Symptom Charts" for examples). Whenever you have a unit that fails to power up, you should follow this procedure before replacing any modules.
1 Unplug the computer.
2 Remove the battery from the logic board. (See Take Apart for instructions on how to remove the battery.)
3 Disconnect the power supply cable from the logic board and then press the Power On button. (See "Logic Board Diagram" later in this chapter to locate the Power On button.)
4 Wait at least 10 minutes before replacing the battery. Make sure the battery is installed in the correct +/- direction.
5 Reassemble the computer and test the unit.
Note: This procedure resets the computer’s PRAM. Be sure to check the computer’s time/date and other system parameter settings afterwards.
Note: If this procedure resolves the problem, claim an adjustment on an SRO. If not, replace the defective component and DO NOT claim the adjustment procedure.

 

[Jon183]

Can you boot off a CD to use disk first aid?  I tried 9.1 on my 7200/90 and it seemed very sluggish. 

You replaced the PRAM battery and I think on these Macs you need to reset the Cuda chip.  There is a small button on the motherboard that resets the chip.  Do a search for the 7200 service source manual to learn how.  That may get it going again...

The cuda reset button is right above the PCI slots.

I copied the relevant bits from the manual:

The Cuda Chip
The Cuda is a microcontroller chip. Its function is to • Turn system power on and off
• Manage system resets from various commands
• Maintain parameter RAM (PRAM)
• Manage the Apple Desktop Bus (ADB) • Manage the real-time clock
Many system problems can be resolved by resetting the Cuda chip (see Symptom Charts for examples). Press the Cuda reset button on the logic board to reset the Cuda chip. (See "Logic Board Diagram" later in this chapter to locate the Cuda reset button.) If you continue to experience system problems, refer to "Resetting the Logic Board" later in this Basics chapter.
 
Resetting the Logic Board
Resetting the logic board can resolve many system problems (refer to "Symptom Charts" for examples). Whenever you have a unit that fails to power up, you should follow this procedure before replacing any modules.
1 Unplug the computer.
2 Remove the battery from the logic board. (See Take Apart for instructions on how to remove the battery.)
3 Disconnect the power supply cable from the logic board and then press the Power On button. (See "Logic Board Diagram" later in this chapter to locate the Power On button.)
4 Wait at least 10 minutes before replacing the battery. Make sure the battery is installed in the correct +/- direction.
5 Reassemble the computer and test the unit.
Note: This procedure resets the computer’s PRAM. Be sure to check the computer’s time/date and other system parameter settings afterwards.
Note: If this procedure resolves the problem, claim an adjustment on an SRO. If not, replace the defective component and DO NOT claim the adjustment procedure.

Ill follow the procedure properly for replacing the battery. I managed to boot from a OS 9.0.4 CD that I burned with transmac and I have wiped the HDD.