68kMLA Classic Interface

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Color Classic Startup Troubleshooting
Posted by: jdlanza on 2020-09-17 20:13:53
Okay, experts, here's what I've got.

CC without the mobo installed powers up.  Fans spins, etc.

Insert the mobo, and no joy.

Left it plugged into power overnight, still no joy.

Removed the PRAM battery, still no joy.

Inspected the mobo, but I don't see any evidence of damage, cap leakage, etc.  Leads to the connector are bright and shiny.

At this point, my main suspects are the ADB ports.  Any thoughts?

johnl
Posted by: bibilit on 2020-09-17 20:23:49
Assuming you have not replaced capacitors or cleaned the board, there is not much i can say.

Battery is not required and connectors never troublesome.
Posted by: jdlanza on 2020-09-17 20:40:43
One more piece of information that may help: the system failed "overnight."  Literally.

The evening prior I had been working on the machine, got the system loaded on a SCSI2SD, etc.  Shut down.  The next morning -- nothing.

What would cause this kind of abrupt failure?

johnl
Posted by: bibilit on 2020-09-17 21:16:46
Caps, Egret chip, goo issues....
Posted by: jdlanza on 2020-09-18 01:08:50
Given the state of the board (see below), I don't think it's a cap or goo issue, but then I may not know what it is I am looking for.  Am I missing something obvious?

In the meantime, I'll do a search for troubleshooting the egret chip.

johnl

IMG_6700.jpg

IMG_6701.jpg

IMG_6702.jpg
Posted by: Daniël on 2020-09-18 01:11:46
The third picture really shows that this board needs a recap, as well as a thorough cleaning. The solder and solder pads around the caps and other components have some heavy corossion from years of capacitor leakage.
Posted by: jdlanza on 2020-09-18 01:15:38
The third picture really shows that this board needs a recap, as well as a thorough cleaning. The solder and solder pads around the caps and other components have some heavy corossion from years of capacitor leakage.
Well, I did admit that I didn't know what I was looking for!  🙂   Now I know.

Any recommendations for US-based recapping services?
Posted by: bibilit on 2020-09-18 06:06:57
Yes it’s obvious. 

The Egret is the chip next to the battery holder, capacitor and oscillator, the picture is blurry but i am pretty sure legs are corroded/contaminated as well. 
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