Just got a Broken Color Classic! Looking for advice

[Mac128]

Why are you guys assuming that it is the logic board and not the analog board? The fan doesn't even start up, although I do hear the CRT trying to start -How easy is it to get the power supply? There is a working Performa 550 on ebay right now that I am considering for CC parts - does this make any sense? I will inspect the logic board soon for any observable issues, and consider washing it.

Depends on the sequence of events. Are you hearing the CRT when you flip the back switch or when you press the power key on the keyboard?

If the back switch, this is normal, though the CPU is NOT trying to start up, what you hear is the power surge into the circuits, preparing the components for soft-power up. Nothing else will start up until the CPU starts up, including the fan. Since the logicboard is the conduit for softpower, which turns on the fan, that is why we think that is the problem. The CPU does a check when you press that power key that determines whether the computer can be safely started up. One of the reasons why the PRAM battery must be functional as that is one of the checks. Also, a common problem with the logicboards is leaky capacitors. While it's possible the same problem exists on the PSU, it's more common on the CPU. I've never heard of it on the Power board.

If this is happening after you press the power key, then there may be a problem with the PSU as the trigger is making it to the PSU, but it is unable to complete the power-up cycle.

The 550 parts can be used on the CC PSU, but they cannot be directly swapped due to the size difference. So the 500 does not do you much good unless you know you have a bad PSU part or plan for one down the road and are prepared to work with a soldering iron. Opening the case is easy enough. Just unscrew all of the screws and pull the back off revealing the CRT & PSU.

As for washing the logicboard, it has been pointed out that Apple did the very same thing before putting it into the computer. They wash all of the boards to remove solder flux. They most likely use purified water. You should use no dishwashing soap for sure and do not dry them in the dishwasher. An alcohol dip following the wash cycle will help speed air drying and rinse any hard impurities in the water.

 

[System6+Vista]

Fantastic, thank you. To clarify, I hear the noise as soon as I switch the master switch on the back of the unit. I hear and see no difference when I press the soft-power key on the keyboard. I guess this means logic board. I will inspect the logic board, and probably post a picture (due to my inexperience) later today.

 

[System6+Vista]

Okay, I've got the logic board out and apart from a little dust, it looks pretty good. Nothing dubious, unfortunately. There may be a little tarnishing on the big white piece that connects to the rest of the computer. My father is recommending that I use his contact cleaner (metal contacts, not optical) to work on this. I took three pictures, what do you guys think?

http://www.fileden.com/files/2008/8/29/2072047/CClogic1.JPG

http://www.fileden.com/files/2008/8/29/2072047/CClogic2.JPG

http://www.fileden.com/files/2008/8/29/2072047/cclogic3.JPG

 

[phreakout]

If you aren't aware already, CCs use "pseudo-soft power". You have to flip the switch, then press the power button on the keyboard to turn them on. The switch alone doesn't power up a CC. I recently bought a CC for $25 from a seller who didn't understand this and passed off the CC as dead because the power switch on the back didn't start it. I feel a little guilty about taking advantage of his ignorance, but on the other hand...
If you still can't get it started, and you don't mind gutting it, then you could swap out the guts and install a new LCD or CRT along with a mini's guts or something similar.

Peace,

Drew

He's right about this. But before you get too carried away, may I make some suggested steps to verify what could be dead?

1.) Reseat the Lithium backup battery and press the red button (S1) on the logic board. Don't hold the button in, just press it one time. This button is a reset for the Power Management Unit (PMU). Then try powering up the CC from the keyboard. If this doesn't work, move on to the next step.

2.) Pull the logic board out of the CC. Remove the RAM and the vertical card next to the RAM (I think that's the ROM SIMM or it is a cache card). Put the logic board back into the CC and turn it on. You should hear some kind of tone one time, but the machine won't boot the OS. This is okay; in a way, you're kind of shocking the CC awake. Next, turn the CC off, pull the logic board out, reseat the RAM and the other card, and put everything back together. Now, turn on the CC. You should hear the startup tone and it should boot from here. If you get a startup tone, but no video, you could have a bad logic board, Power Analog Video (PAV) board, CRT or Power Supply Unit (PSU). But if the PSU is bad anyway, nothing will turn on. Oh sure you'll hear something click on, like the flyback transformer, but the voltage measurements could very well be under the needed amounts.

3.) From here, it's hard to say what is bad until you start measuring voltages on the PAV board, PSU and logic board. PAV boards on these type of Macintoshes are quite common for failure after so much use. In fact, I would even consider going as far as to say all of the "All-In-One" Macintoshes with CRTs are at risk. Another problem on the PAV board might be that there are cold solder joints or "cracks". You can try taking a soldering iron and touch up the solder a bit on the entire board. While you're at it, check for bad capacitors, flyback transformer and anything that looks burnt, like fuses or burn marks on the board.

4.) If you don't want to muck around with a soldering iron, I would suggest replacing the whole board. These aren't hard to find; look online here or eBay or other resources for refurbished parts.

Try the above steps and get back to us on your results. Good luck.

73s de Phreakout.

 

[beachycove]

Note that you have a 68882 in thet thar logic board.

Not so easy to find one of those.

 

[System6+Vista]

Bad news: I removed the two RAM sticks, and the bigger stick, which it says is the VRAM SIMM. I pressed the red reset button. I also cleaned the contacts to the rest of the computer, and still nothing.

Is the 68882 the optional co-processor? Very interesting. I'd swap it in a second for a working logic board.

I will wash the logic board later this week, but again I am wondering if the PSU is shot and not supplying enough voltage anywhere else. How standard are these power supplies and how easy are they to find?

Also, I am not seeing any CC logic boards on eBay, where else can I look?

 

[LCGuy]

The power supply and analog board are all one self-contained unit, which is unique to the Colour Classic and Colour Classic II. Unfortunately most, if not all of them are pretty much on their way out, meaning that these days, repair is most likely a better option than replacement.

 

[phreakout]

System6+Vista,

If you decide to disassemble the CC, can you post pictures of ALL the components you pull out of it? What I mean is completely detailed pictures of the logic board, power supply and PAV board units. I just need to see up close the condition of each of these parts, to determine what next should be done. I need assurance that everything looks in order for proper operation.

Sorry for the retentive attitude, but I'd hate to see a good Retro Macintosh go in the dumpster, be turned into a MacQuarium, etc., over something that is so simple as to why it wasn't working in the first place. xx(

Okay... got that out of my system. I'll shut up now.

73s de Phreakout.

 

[tomlee59]

Rather than guessing, why not just *measure* the power supply voltages? That way, you can quickly rule out/in the "dead PS" hypothesis.

And I'm not precisely sure what you mean by "hearing the crt". Could you say a bit more about what you are actually hearing? There is a gentle "staticky" crackle that can accompany the appearance of high voltage; there can be a sound associated with the vertical sweep (it'll be a buzz/hum, emitted actually by the deflection yoke); and there can be a horizontal-sweep noise. However, unless you've got the hearing range of a bat, I doubt that you could hear a CC's horizontal sweep (regular TV, sure, but a CC? Doubtful).

As to washing the logic board (should you decide that it's necessary): As another poster noted, many folks here -- including me -- have washed quite a few logic boards with a good success rate. It's been a pleasant surprise, in fact, just how well this procedure works. I was certainly as skeptical as alk until I actually ran the experiment. Just dry thoroughly before reapplying power, and you (and the board) will be fine.

 

[phreakout]

Well, I'm on the assumption that others may not have the skills or equipment on hand to check voltage levels on the power supply. Some may not want to work hands on with high voltage, so I'm giving other alternatives. I know it sounds like guessing, but I at least hope to narrow things down to where the problem is originating. For all I can determine, he could have a bad logic board, PAV or PSU; I don't have any service repair manuals on hand for the CC and am going a bit blind.

Sorry, for wasting everyone's time. I don't believe I'm that bad of a technician. I've worked in a local Macintosh Repair Shop fixing these machines and I got all sorts of different patients on my bench. Very rarily will I get an older toaster Mac to work on. But I have replaced numerous PAV boards from out of iMac G3s and eMacs. Most of the rest are either LCD displays or they are strictly desktop and laptop systems, without CRT displays.

I'm at least hoping I can stay sharp and help point others in the right direction. Use my advice if you want to, but you don't have to. I'm only here to help.

73s de Phreakout.

 

[System6+Vista]

Phreakout,

If you are truly willing to look at all of my pictures and help, I'd me more than happy to disassemble and take copious photos. I have been working with computers since age 4, but I know next to nothing about circuitry and electrical components; my experience usually ends at installing RAM, PCI cards, hard drives, etc. The Color Classic (especially this one in such fantastic aesthetic condition) is my dream Compact Mac, and I have told myself that I can stop collecting if I get one working. That said, whatever pictures can help you diagnose this sick puppy, I'm ready to take them.

The "CRT sound" is the familiar sound of turning on any CRT monitor or TV. My father (I am a college student living at home over summer) described it as the CRT transformer, but it is the short (less than 2 seconds) faint sound that rises in pitch, and if you really need I can take a video or make a sound clip. I am not talking about the very high frequency hissing sound that you can hear from TVs sometimes, but rather a faint, but audible to everyone, sound of giving power to a CRT.

The CRT noise is the ONLY response I get the from the CC whatsoever. I hear it every time I switch the main power on, and it gets fainter and disappears if I flip the switch many times within a few minutes, but it will do it again if I leave it off for a day or so. I have plugged two sets of ADB keyboards/mice into both of the ADB ports (different times) and pressing the power keys does absolutely nothing. I hear no fan, no hard drive, no floppy, no light and see nothing on the CRT either. Once I left the main power on for a long time and I thought I heard more CRT noises.

I do have a power meter, and know how to use it so if you can show me where to test it I can give you the readings. As long as that is mostly safe!

 

[System6+Vista]

Also, I found Apple's Service Repair manual relativley easy on google, but it is of no help. According to the troubleshooting guide, I should replace my logic board because I have already put in a new battery and connected the keyboard. Perhaps there is a more in-depth manual somewhere else.

 

[tmtomh]

Also, I am not seeing any CC logic boards on eBay, where else can I look?

Sent you a PM.

M

 

[equill]

System6+Vista

Many CCs that have not been used for some time need up to 24hr—or more—just sitting quietly with mains power connected and switched-on at the rear of the Mac before there is even the ghost of a chance of startup from the keyboard. You presumably know by now whether your CC uses a 4.5-V alkaline or a 3.6-V lithium PRAM battery. If you have replaced the PRAM battery already, and checked the MLB and analogue board for condition, goodness of all breakable and remakeable connections, and checked that all inserted or attached components appear to be genuine, you give yourself a better chance. Capacitor leakage is not unknown even in CCs. If you read the references above you will find much that is useful in the resuscitation process.

The CC does not have a PMU, which requires (in much later Macs than the CC) a single button-press for not more than 1sec. The CC has a CUDA, which functions only for as long as the button is held in. PMU and CUDA do much the same things, but the PMU is much more complex (a computer-within-a-computer) than the simpler capacitive-discharge CUDA. However, if you have had the MLB out and the battery removed, you have already reset the MLB. When you are ready to fire up the CC, slide the MLB into its newly-cleaned edge-connector, and then hold in the CUDA button for 20sec just before you replace the case bucket. If it does not then start up from the keyboard immediately after mains switch-on, use the soak-on-the-mains-for-a-day procedure. If you do not hear an audible 'klunk' (akin to the sound of a relay pulling-in) when first any of the pseudosoft-powered Macs from CC to LC/Performa 3-digit models is switched on at the rear, you can expect that there will be some time before soft-power switch-on will be possible, and then only if the Mac is capable of working.

de

 

[System6+Vista]

Fantastic. I have followed your procedure with the little red button, and am leaving the CC with the main power on for the next 24 hours. What is the "soak the mains" method? I am also awaiting instructions on where to test voltage with my multimeter from the PSU so I can figure out if its the PSU or MLB.

 

[equill]

The SOTMFAD procedure is that already mentioned. Switch the cleaned, refurbished, checked and reassembled CC on with the rear mains switch. Try to start up from the keyboard. If there is no response, or if you hear a rapid clicking in time with flashing from the power-light on the front, leave the CC to soak for another couple of hours. Leave the rear mains power switch on. Try again after a couple of hours of soaking. If you get no startup by the end of two days of soaking, and periodic attempts to start up, the CC is not in a condition to start up, and you have a greater problem than failure of pseudosoft power-on. There is a good side to this: every one of five CCs to pass through my hands (and four of them are still with me, years later) has responded to this revivification process after less than a day, given that the prior cleaning, checking, reseating, replacement, &c has been done.

de

 

[equill]

I should also have mentioned that not all the MLBs of CCs have a CUDA switch. In such cases the MLB is reset when you remove all power to it (by removing the battery, of whichever voltage, and taking the MLB from the computer) for at least 10min. Alternatively, if resetting just before reassembly is the objective, disconnect and slide the MLB out of its edge-connector a couple of inches or so through the in/out doorway, and then remove/disconnect the battery. After the 10min, replace/reconnect the battery, slide the MLB back into place, and replace the in/out door before you reconnect the mains cable and switch on.

de

 

[System6+Vista]

Yesterday, I left the CC mains on and left the house for the night. I just returned, and expecting nothing I clicked the power key on the ADB keyboard. The Color Classic was turned away from me, but I heard the sound and the entire machine booted up normally! It is now in perfect working condition and has 8mb of RAM, a 40mb hard drive and the color and sound are brilliant. It seems like all it needed was a new PRAM battery and to be left on for a while!

Thank you to everyone who helped me with this. This is really my dream 68k Macintosh. Now to get an ethernet PDS card!

 

[tomlee59]

Well, I'm on the assumption that others may not have the skills or equipment on hand to check voltage levels on the power supply. Some may not want to work hands on with high voltage, so I'm giving other alternatives.

Given that he's gotten it working now, this is now somewhat irrelevant. But to respond to your comment, he was already talking about servicing the unit, replacing the PSU, swapping boards, etc. So given that, recommending that he make some simple measurements first was a logical one. Also, you seem to be assuming that exposure to "high voltage" is a necessary accompaniment to making such measurements. That isn't true; at least one very revealing measurement (of the +5V supply) can be made at the scsi or adb connector. Opening up the unit isn't even necessary.

I believe strongly in making such measurements before undertaking the more drastic steps he'd been considering. This is just basic troubleshooting 101. The random flail method can succeed, but a more structured approach is more reliable.

 

[joshc]

Well I think kudos to equill for suggesting what he did. It certainly didn't come into my mind at all that it just needed the power turned on for a while.