Classic II: Boot chime after two or three minutes powered on

[chrisrueckert]

My Classic II has a recapped logic board and a known working analog board. Voltage measured on the floppy port is stable 4.98V and 11.95V. The Mac powers up when switched on (fan, disk spinning) but not boot chime. After two to three minutes, it suddenly chimes and works flawlessly.

Any thoughts what the issue might be for the delayed boot?

 

[bibilit]

Ram issue ?

 

[chiptripper]

Perhaps a dying hard drive, is it original?

 

[GRudolf94]

You probably have a bad trace around Egret. It is responsible for generating the reset signal to the rest of the system, and... Well, I know Cuda will only reset the machine if it senses trickle and main 5V are both present. Egret probably doesn't care about trickle, but probably needs to see the PSU 5V rail come up before asserting /RESET.

From Bomarc's eeeh schematics, we want to see if pin 26 has 4.7kOhm to the 5V supply, and if it rises to 5V with the machine turned on. Might wanna check 23 too, that's probably fast reset since it goes to U18. Also check if 12 goes to 5V. Totally forgot U12 is the battery monitor IC. Very important that that works.

 

[chiptripper]

Egrets get very crusty on Classic IIs. Surrounded by caps. I recapped one last night and the electrolyte had crept under the board directly below the Egret and gunked up the solder and traces on several ceramic caps too.

 

[chrisrueckert]

So, I measured the voltages as per the suggestions above. They were all within the specs. Both before the chime and after. However, I recapped the analog board. Now the Classic II boots right away. Problem solved. Thanks all for your help!