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SE/30 logic board is just dead

Yes, to both... the supply works I tested in on another SE/30 logic board and it works fine . The logic board is recapped and cleaned in the ultrasonic cleaner

 
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Then your issue is in the analog board (probably). Check out an online PDF of the dead mac scrolls, think theres something on the analog board youve got to check out.

 
I tested another Logic board in the same computer and it works. So I doubt it is the analog board.

 
Got a picture of your logicboard?

Check if it is stuck in reset. The reset line should become high shortly after power is supplied.

The reset line is running close to one of the through hole resistor solder spots and can get damaged and shorted to ground at that spot.

 
Ah, it's still early on new year morning :P

I meant to say capacitor instead of resistor.

The one in question is C2. The reset line is running right next to one of its solder spots and sometimes gets damaged when removing the cap.

You can use a multimeter to check the reset line. It should read 5V otherwise the system is stuck in reset for some reason.

Reset can be checked on pin 5 of UB11 for example or on A12 of the PDS connector (I would check on both places to see if the reset line isn't broken somewhere in between)

 
No short to ground on pin 5 of UB11. Do you mean the power and video connector J12?

I think that line you're talking about goes from pin5 on UB11 to pin 40 on UE10. There is no short to ground. not OL between the two 

 
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The PDS slot is at J13.

Check if the reset line reads 5V while the machine is running. It does not have necessarily be shorted to ground.

 
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I don't have access to the logic board while it is on the power connector. If the line by the C2 capacitor has an issue it's either shorted to ground or OL

 
Get one of those ATX power supply extension cables. They fit into the logicboard power connector on the SE/30 as well and you will be able to run the logicboard placed next to the chassis.

Otherwise troubleshooting will be hard.

View attachment 23447

 
I don't have one of those, but I can connect the board to my bench supply tomorrow. or better later, it's tomorrow already.

 
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I think I found something. For some reason I don't have connectivity from C2 to pin 11 and 12 of UB11 which is the 12v+ input of the sound chip.

 
Here is an update, I now have 12v at C2 and on the other side of the board at C25.No 12v at the UB11 pin 11 and 12. I can run a jumper from C25 to UB11 pin 11. and the board will boot to a SIMASIMAC screen and start up bong.

Somehow the schematics do not correlate to the components on the Logic Board, which makes diagnosis a bit tough. 

 
Bolle said:
Get one of those ATX power supply extension cables. They fit into the logicboard power connector on the SE/30 as well and you will be able to run the logicboard placed next to the chassis.
Click to expand...
That is a neat trick.  Is something like that available for the Color Classic?  Can you point me to a link?  Very cool!

 
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