The Color Classic has fallen again!

[System6+Vista]

Hi Folks,

About two weeks ago I made this thread: viewtopic.php?f=7&t=10005 asking for help with my Color Classic, which finally, for two days, worked perfectly. Over the past few days while the website has been down the Color Classic has not been able to startup once, no matter how long I leave it plugged in for. Now that I know it can work, I'm starting a new thread to simplify things and again, to beg for help. Its especially disappointing because my Ethernet card from adoptamac.com just came in the mail.

A breif summary of what's happened:

Got the Color Classic, looks great, doesn't do anything. When plugged in and master switch is flipped I hear sound but soft power does nothing.

New PRAM battery, still same situation.

Reset PRAM memory using red button on logic board. Cleaned partially tarnished contacts on back of logic board where it connects to rest of computer.

Took out RAM, VRAM and tried to boot, still nothing.

Left computer master power on for 24 hours, came back, pressed soft power and PRESTO! It woke up as if nothing had ever happened. My girlfriend even got an entire game of Oregon Trail on Color!

Came back the next day, adjusted some settings and got acclimated to the system. Floppy works great. Sound is loud and clear. Microphone records well. Hard disk sounds good, works fast. Video brilliant. Decided to leave the master power on and....

Next day - nothing! Have left it plugged in and master power on since (about 3 days) and still nothing.

Yesterday I unplugged it to give it a rest and stop needlessly sucking electricity, and awaiting further instructions.

So...any ideas? I do have a power multi-meter and am comfortable testing power levels as long as someone can point me to where to test. Now that I know this Mac works, I feel much better but am very depressed that it simply won't turn on. I am looking forward to doing some typing in that fancy version of WordPefect it has...

thank you,

Dave

 

[beachycove]

Have you tried washing the logic board? Seriously. Stick it in a dishwasher if possible (only it, obviously, with no soap), wash, remove, and let it dry in a warm, ventilated place. It'll maybe take a couple of days to dry thoroughly. You can scarcely make things worse than they are.

Alternatively, in Conquests someone recently got a CC logic board. You might be able to persuade that fellow member to part with it.

 

[joshc]

I believe beachycove is referring to myself. I recently acquired what appears to be a CC logicboard from a working system (its dusty). Dead PRAM battery (now removed), but otherwise looks fine. No RAM or FPU. Let me know if you want it.

 

[tomlee59]

If you own (or have access to) another keyboard, give that a try first. You never know; perhaps your keyboard is the problem, and not the computer proper.

 

[System6+Vista]

Sorry, I guess I forgot to mention I've tried two sets of ADB kebyoards and mice (even different models) that are compatible with ALL of my other compacts, and no difference. I'm getting a new motherboard from tmtomh, which is very exciting. Worst case scenario I spend a little money to know that its my analog board if his motherboard doesn't work!

 

[Dennis Nedry]

And you can always keep the extra board or sell it to someone else on here, even if it's faulty. One of us can fix it. The worst you've lost is the cost of shipping in one direction.

 

[equill]

... Now that I know this Mac works, I feel much better but am very depressed that it simply won't turn on. I am looking forward to doing some typing in that fancy version of WordPefect it has...

Your predicament is not uncommon amongst owners of older Macs. You probably know little about the CC's history before you became its owner, and what structural or electronic components were ready to break or fail, so all that you can do is go back to square one. Take off the case bucket. Reset the MLB (all power removed, including the battery) for 20min. Insert the battery and measure its voltage in circuit. If that is 3.3V or lower (regardless of lithium/alkaline), replace the battery. Hold in the CUDA switch for 40sec (it needs time to do its job, although the MLB was deliberately not powered for 20min) as your last act after reassembly before replacing the MLB's I/O door, or the case bucket, and then reattach the mains cable and switch on. Soak the CC on the mains again, trying at intervals to start from the keyboard.

If you cannot start up, you are firmly pointed in the direction of full-scale inspection/replacement/voltage-check, beginning with the mains cable and working through keyboard, SCSI power cable (for both 5V and 12V confirmation) and so on. If you can use known-good substitutions at any point, do so. If the RAM or VRAM has been augmented, try with both RAM cards removed (ie, return to base configuration), or with the single VRAM card out. If a substitution is not successful, put the original back before moving to the next test. Every potential failure point, even those that were new to Compact Mac construction—such as the flat-cable assembly—should be examined and cleaned. The FCA is the junction-point for MLB, drives and front pushbuttons, and therefore needs to be in place, intact and clean. If checking the voltages and components brings no joy, you may indeed be faced with replacement of components, boards or CRT.

de

 

[System6+Vista]

Equill, I couldn't thank you more. Just when I learned I wouldn't be getting a new logic board, I tried your instructions again and Presto! Worked like a charm. So today it wouldn't start again, but I've learned something - If I want to use my CC any given day, I need to take out the motherboard, hold down the CUDA button for a minuite and then plug it in, flip the switch. Sometime in the next hour, if I keep hitting soft power it seems to always work - sometimes 5 minuites after, sometimes an hour. Perhaps it will surprise me Tommie and break this rule, who knows?

So I'm wondering, if this CUDA button really is the fixing catalyst (and of course it may just be obscuring something else), what does that mean in terms of the issue? Something I can fix?

 

[Mac128]

Soak the CC on the mains again, trying at intervals to start from the keyboard.

What exactly is this doing? Is it charging capacitors? If so, is it aging capacitors which have leaked and therefore cannot hold a reliable charge? It certainly acts like an old car battery that no longer maintains a proper charge. The car will start, but not reliably and only after sitting for a while, until eventually it won't even hold the minimum charge necessary to start it at all.

 

[tmtomh]

I feel like an idiot asking this since I've worked on CCs for years and even modified them, but...

... where exactly is the CUDA button on a CC motherboard? I can't find it on either of mine.

M

 

[JDW]

There are two keywords that I noted while reading through this entire thread today: keyboard & capacitors.

While it may not be the root problem in this case, I feel it important to mention that the electrolytic capacitors used in some keyboards leak and need replacing as badly as the caps on many logic boards (such as the SE/30 logic board).

I myself had many troubles with a IIgs keyboard attached to my SE/30. Sometimes I would tap the keys but I wouldn't get a response on screen. But after powering off (for safety) and then disconnecting and then reconnecting the IIgs keyboard to my SE/30 and then powering on, the keyboard worked fine. In the past, I had opened up the keyboard and fixed some cracked traces, cracked because the ADB ports themselves were merely soldered to the PCB without any strain relief, hence anyone pressing in the cable too hard could apply undue pressure on the powers, which in turn ultimately cracked the traces on my IIgs keyboard. But even after I had fixed those traces, I would still get the same problem from time to time, where I would tap on the keyboard but nothing would show on screen.

Last week I opened the keyboard again and examined the two caps with a magnifying glass. Sure enough, they had leaked. I swapped them out with tantalum caps and found that all is well now. (I also used some hot glue on the back side of each ADB port to eliminate any future trace breaking.)

So I don't know if capacitors and/or leaked fluid is playing a role here. But in my experience, it likely is.

 

[equill]

There were several subtle variations in the P250/CC line: 4.5-V alkaline or 3.6-V lithium batteries and presence/absence of a CUDA switch being chief amongst them. If none of yours has a CUDA switch (although the solder-pads for one may be evident near the rear right of the MLB) it only obliges you to remove all power to the MLB for 10-20min to reset the MLB, which is as safe a way of resetting as anything that the CUDA can achieve.

As for the harder question: whaffor the need to soak a CC on the mains? before it will start up from the keyboard, the plain truth is that I dunno. It works in the vast majority of cases in CCs that have been off the mains for years. (One that I acquired had not been used for ten years or so, going by the dates of System files, but it responded to the SOTMFAD treatment, and still goes three years later.) Only a complete circuit diagram could support a guess at the cause of the behaviour, but it is common to all the pseudo-soft power Macs as far forward as the 5500. It definitely has nothing to do with the CPU, because all three of my 5500s have G3 upgrades. I could lean to the guess at large filter caps in the power supply needing to repair/be repaired, but caps that have grown shorts through the dielectric usually need a massive instantaneous discharge to burn off the dendrites, and it is still a risky 'repair'. The signal that such power supplies as the Macs have will need palliative care before use is the absence of the klunk when mains-power is switched on. What klunks I know not, and will not have time to explore this side of Armageddon, I fear.

de