Dead Classic II, re-capped analog & logic, still dead

[JC8080]

I have a non-functional Classic II I picked up recently.  When I bought it, when I powered it up all that happened is the fan came on, no other signs of life.  I opened it up and found the capacitors on the analog board were leaking badly.  I recapped the analog board and fired it up, and got a checkerboard screen, once.  After that when I powered it on I once again had nothing - just the fan, nothing else.  I re-seated the RAM and ROMs, no change.  The electrolytic capacitors on the logic board showed signs of leakage so I ran the board through the dishwasher twice, warm water, no detergent.  Followed up with a good cleaning with 99% isopropyl alcohol.  No change.  Knowing the logic board would need to be recapped at some point I went ahead and did that.  After replacing the capacitors I checked continuity from each leg to its respective via to ensure there were no damaged traces, everything is good.  I powered the machine up, no change, still dead except for the fan.  I checked voltages and have almost exactly 5v and 12v, like 4.95 and 11.95.

Most of the Classic/Classic II troubleshooting info I have found involves diagnosing when the machine is partially functional, with a checkerboard screen or other display issues.

Does anyone have any thoughts on what to check next?  Thanks!

 

[dochilli]

Could be broken solder joints on LB or AB. Check the connections from AB to LB. Resolder the connections.

Where did you check the voltages? Floppyport?

 

[bibilit]

Many issues in the Classic II are related to the now infamous chip named Egret. 

Bad or simply goo contaminated. 

Can lead to checkerboard issues, black screen or no boot. 

Dont saying is this, but pretty common. 

If you have a scope, you can have a look at reset, clock... first. 

 

[JC8080]

Could be broken solder joints on LB or AB. Check the connections from AB to LB. Resolder the connections.

Where did you check the voltages? Floppyport?

I'll take a look at the connections AB to LB next time I have the board out, yes checked at the floppy port.  Thanks!

 

[JC8080]

Many issues in the Classic II are related to the now infamous chip named Egret. 

Bad or simply goo contaminated. 

Can lead to checkerboard issues, black screen or no boot. 

Dont saying is this, but pretty common. 

If you have a scope, you can have a look at reset, clock... first. 

Thanks, good to know.  I'll have a scope in a couple days.  I've never used one before, I'll have a bit of guidance from a friend but nothing Mac-specific.