Sideburn
Well-known member
Yeah. That why im making a molex cable.. i can then jumper pin 10 to pin 9 to manually power it on and selectively supply the 5v and 12v to the board and put an amp meter on it to check the load.
-
Updated 2023-07-12: Hello, Guest! Welcome back, and be sure to check out this follow-up post about our outage a week or so ago.
Anyone up for some IIcx troubleshooting assistance? We have clocks but no activity...
- Thread starter Sideburn
- Start date
Phipli
Well-known member
Hum. It might be in the hardware reference book but I'd have to research. It is for the Mac II, but the easy thing to say is look at the ratings written on the power supply. Less than that, minus the allocation for any empty NuBus slots.
Phipli
Well-known member
Old computers ran almost everything off 5V, even an old hard disk could use 2A on 5V.
12A is the maximum, but isn't an insane amount.
Sideburn
Well-known member
Tested all the RAM with the Mac plus. All but one SIM was good.
While using the bench ATX supply under load on the board the voltages are 4.6v on 5V rail and 12.8
no load = 5.1v and 12.5v
12v increases in voltage under load.
I should use only bank A full of SIMMS I suppose
While using the bench ATX supply under load on the board the voltages are 4.6v on 5V rail and 12.8
no load = 5.1v and 12.5v
12v increases in voltage under load.
I should use only bank A full of SIMMS I suppose
Last edited:
Phipli
Well-known member
Only SIMMs up to 1MB will work in the Plus, I thought you were using Plus SIMMs in the IIcx, not IIcx SIMMs in the Plus.
Sideburn
Well-known member
That’s what I was thinking. I haven’t noticed anything getting hot but I’ll check it. I have a thermal imager too.
Sideburn
Well-known member
I took the simms out of the plus and set them aside and then tested all of the iicx simms I have.
They are 1mb simms totalling 4mb per bank which is the maximum amount you can put in a Plus.
So now the IIcx has 4 1mb known good simms in bank A and bank B is empty.
Sideburn
Well-known member
OK OEM power supply is good,. the problem is the +5 feed to pin 9 to turn it on is too weak causing it to collapse. if i disconnect that pin and jumper it myself to pin 10 then the board comes up (with the sad mac). while the board is running if i connect that back the power supply collapses again even while i am jumping pins 9 and 10 together.. if i add the trace on the board to pin 9 it kills it.
so its like the trace to pin 9 on the board is pulling it low.
WIth the power supply running trace from board to pin 9 disconnected and me jumping 9 and 10 together, the board is running and when i check the voltage of the trace on the board to pin 9 it is .5v and should be 5v.
Ive let the board run for 30 mins or so and nothing is hot to the touch. the Nubus chips are a little warm. Probably the warmest ones on the board.
so its like the trace to pin 9 on the board is pulling it low.
WIth the power supply running trace from board to pin 9 disconnected and me jumping 9 and 10 together, the board is running and when i check the voltage of the trace on the board to pin 9 it is .5v and should be 5v.
Ive let the board run for 30 mins or so and nothing is hot to the touch. the Nubus chips are a little warm. Probably the warmest ones on the board.
Sideburn
Well-known member
I fixed the power circuit issues. So now the soft power and original PSU are working. Still tracking down the chime of death cause.
Quick question. Does a healthy IICX make a normal startup chime if it has ram but no video card in the NuBus slot?
Would like to know if I can put video aside while troubleshooting. Haven’t found any solid answers online though.
Quick question. Does a healthy IICX make a normal startup chime if it has ram but no video card in the NuBus slot?
Would like to know if I can put video aside while troubleshooting. Haven’t found any solid answers online though.
Yes it should do.
Phipli
Well-known member
It would then sad chime though wouldn't it? When it couldn't find video to initialise? Not sure, don't run machines with absolutely no video at all.
Sideburn
Well-known member
Thanks for confirming. The problem is I don’t know what the state of the video cards are so I want them out of the loop. With none card in there’s no difference. Same death chime the instant I power on and no activity on the display. With the other card there’s no chime at all. So I plan to resolve the startup chime without the cards first.
