Macintosh Color Classic I, Pattern Failure

[uniserver]

here is what happens to some of those Color Classic Mainboards, and its really got me annoyed.

NOT super Annoyed, because none of my personal Color Classic Mainboards have done this but enough of other peoples

have done this.

here is the scenario.

My Color Classic has a lc520 main board in it… and it works great… everything is up to snuff…. no issues what so ever.

I'll re-cap a Color Classic I mainboard for someone.

Give it the ROYAL treatment… i clean the pads up, wash the board…

then hit it with air compressor and blast it off so its nice and dry…

Do a fresh re-cap.

I mean heck i will even go the extra mile and and saturate some paper towel with IPA 91% and clean the main connector.

I go to power up the thing on from the keyboard and nothing…

so then i check the PRAM battery… pop a good one in… still nothing.

so i am telling you that i have checked all my remedial bases.

So with the unit switched on, i pull the main board out, and slap it back in… and BOOM , Apple bong.

boots works fine… even the restart keystrokes work!!!!

but power it off. and the power button no longer kicks it back on just like before.

so i follow the power button all they way to

the Apple/ Motorola chip 341S0417, right next to the two ADB ports and i can even see when i depress the power button on the keyboard, i can see the meter register this.

i have even tried swapping this I/C and it still does it.

I am wondering if there is a way i can install some kind of push button hot wire power on switch.

Slapping the board in and out just to power it up just seems uncouth.

been trying to google pinouts for the header, i can't really seem to find anything.

What on the Color Classic sends the power on signal to the chassis A/B to say POWER ON PLEASE?

i am kinda sick of monkeying around.

Anyone else had this issue? any input would be nice. as i am sure it would help others.

 

[techknight]

My CC board is doing the same thing. Worked one minute, not the next. So i stuck an LC550 board in there.

 

[techknight]

Funny thing is, there are 2 signals to the CC analog board. the ADB power supply, which is nothing more than standy voltage to the ADB IC. then there is the power-on signal that brings up the main supply.

My guess, when you press power button the ADB controller responds and sends the PS-ON signal to the analog board, which brings up the entire machine. When you shut down, the ADB releases the PS-ON line and the machine shuts off.

Now, when pressing the power, and system NOT responding, either the IC is bad (which you replaced). or one of the traces to the ADB IC is open. I "think" Q1 behind the ADB port is responsible for pulling the PS-ON state.

 

[uniserver]

changed q1 still does it.

wish i had the schematic for this pos

 

[techknight]

yea, i dunno. i do know that it appears that IC is in control of it.

 

[uniserver]

i think the issue is in-between the IC / chassis connector.

i think minerAI had a pinout i need to look at his Classic hack thread.

 

[techknight]

i think the issue is in-between the IC / chassis connector.
i think minerAI had a pinout i need to look at his Classic hack thread.

Yea, all it takes is 1 trace. ya know how that goes. lol.

 

[uniserver]

viewtopic.php?f=29&t=19871&start=275

Analog

Connector/

Ribbon

Position Signal

-------------------------

1 = -12 V input

2 = GND

5 = ADB Power supply

6 = GND

7 = Power off command

8 = GND

9 = Composite signal out*

10 = GND

11 = BLUE out*

12 = GND

13 = GREEN out*

14 = GND

15 = RED out*

17 = Brightness control output

18 = GND

19 = Contrast control output

20 = Monitor ID 2*

21 = Audio in (Mic)

22 = GND

23 = +5 V

24 = Monitor ID 1*

25 = Monitor ID 0*

28 = Audio out ®*

29 = GND*

30 = Audio out (L)*

31 = GND*

37 = Sound amplifier control output

yeah i know how it goes.

 

[techknight]

yea, thats the analog board connector. But it still doesnt show the actual pinouts of the CC/LC550 board itself.

Of course if you wanna dig out the loom you can chase that out with a multimeter i guess.

 

[uniserver]

yeah screw this crap… i have no CLUE what is what.

 

[beachycove]

A standard treatment for a "dead" CC has long been to leave it plugged in overnight and then to retry powering on. It can be a strange little machine that way. This has been talked about since way before early 90s logic board capacitors came to be thought universally iffy, and to be needing replaced. So one would not necessarily expect recapping to be enough to get a CC going. There's still some voodoo to do do.

 

[MinerAl]

I could never find anything about the logic board itself, because all the crazy Japanese dudes back in the day were gutting and tossing the stock CC loom and replacing it (after some irreversible chassis mods) with a 5x00 loom interfaced to the CC analog board (which is why I was able to find that connector pin out above).

Google and I spent hours looking for the CC-575 logic board pin out to no satisfactory end. If you find one please send me the link!

 

[uniserver]

A standard treatment for a "dead" CC has long been to leave it plugged in overnight and then to retry powering on. It can be a strange little machine that way. This has been talked about since way before early 90s logic board capacitors came to be thought universally iffy, and to be needing replaced. So one would not necessarily expect recapping to be enough to get a CC going. There's still some voodoo to do do.

I just don't know what this would accomplish.

any technical reasons why this might work?

 

[uniserver]

would this be pin5 - 5 = ADB Power supply ?

[attachment=0]Screen Shot 2014-01-05 at 11.15.52 PM.png[/attachment]

 

[techknight]

I dont think so... but im not sure. i think ADB power supply and STB signal were on the smaller wires.