Colour Classic Not Booting After Correct Sequence & Recap

[LazarusNine]

The answer may be obvious, but I received a non-working Mac Color Classic. I replaced the battery, turned the computer on, hit the power key on the keyboard. Nothing. Cleaned and recapped the motherboard. Nothing. It's the analogue board, perhaps? Will a recap do, or are there perhaps deeper issues with the CC that typically occur? Cheers!

 

[aplmak]

A real easy check before you get any deeper... Some Macs don't boot without the PRAM battery back in... Try putting the battery back in and booting it.. Just a suggestion before you start looking at broken traces on the logic board or the analog/power board....

 

[aplmak]

I mean a known good battery... And then make sure you really wash that logic board.. I use 91% rubbing alcohol in the tub with a clean new toothbrush to get in the little legs of the ic's... after scrubbing with the alcohol and toothbrush do a rinse with the bottle of alcohol... I usually douse my boards with it and let it sit for a little bit to break down any chemical residue on the board then start with the toothbrush.. As uniserver has mentioned before goo can get under the chips.. make sure all your caps have the right polarity going the right direction..

 

[techknight]

This is a known issue, and there are multiple threads on it. It involves a trace being rotten out near the PMU IC. 

 

[LazarusNine]

Brand new tested battery has been in the mobo from the outset (first thing I did). I also gave the whole board a clean using 99% isopropyl alcohol. The most I get out of the thing is a small hiss from the screen indicating that power is definitely flowing through the machine, but boot up of any description just ain't happening.

Techknight: I'll have a look for the thread and also for the rotten trace...

 

[MJ313]

Maybe look at this one too-  http://thinkclassic.org/viewtopic.php?id=537

 

[LazarusNine]

Thanks for the links! I attempted each of the pictured work-arounds. Still nothing.

 

[MJ313]

Do you have a hi-rez shot of the logic board, near that oscillator? Maybe someone can spot something for you...

 

[LazarusNine]

Yeah. Sure thing. I haven't bothered removing the trace wire but will do once others have any suggestions.

 

[techknight]

You might need to remove the PMU chip and take a look underneath it for eaten traces/vias. 

Regardless. You have one of those oddballs that needs extensive troubleshooting to figure it out. 

 

[LazarusNine]

Anyone see anything I don't?

 

[uniserver]

you need to go over that whole board with IPA and a tooth brush i see nasty ness under many of those I/C.

the board need to be washed, cap goo is a serious problem with the Color Classic.

 

[Apache Thunder]

I'm no electrician, but I would have to say that solder joint on C6 looks suspicious (I assume that to be some kind of diode. But I'm probably wrong. ). The solder pad on the + marker looks fine. I'm talking about the one opposite of that.

Visually speaking that's really the only thing I can spot. You'll likely have to bust out some testing equipment like multimeters and stuff to find the problem.

 

[techknight]

Did you try powering up the analog board without the logic board in place? 

 

[LazarusNine]

Did you try powering up the analog board without the logic board in place?

Yeah! It seems to start just fine (fans and everything, etc).

 

[MJ313]

Maybe just say screw it and find a 550 board to throw in there... vroom!

 

[LazarusNine]

Maybe just say screw it and find a 550 board to throw in there... vroom!

If I can find one, I most definitely would!!!

 

[dougg3]

If I were you, I'd check everything in that section of the board. Look at where the vias go and make sure the appropriate components on the top and bottom all have continuity through the vias with a multimeter. I did this on mine by taking a picture of the top and bottom, and color coded the vias. If the power key on the keyboard doesn't work, there's a decent chance it has something to do with the circuit nearby the CUDA chip (U7).

 

[mrpippy]

I had a similar problem with my CC, just one corroded via prevented it from starting up at all: https://68kmla.org/forums/index.php?/topic/24740-color-classic-no-power-issue-debunked/?p=270845