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MAC iicx

Gary C

Veteran Member
Joined
May 26, 2018
Messages
2,256
Location
Lancashire, UK
Hi

can anyone help me troubleshoot a IICX ?

When powered up, I can see bus activity on the RAM & the ROM, the hard drive spins up then down and the floppy is accessed, but I get no tones and nothing on the screen.

I can see a burst of activity on the NUBUS and the memory/rom being accessed on the video card.

So, it looks as if the CPU is running and accessing the rom, ram and the video card then running some access on the disks but not putting anything on the screen and not playing the tones.

What is the normal startup sequence and should I at least get the sad face icon on the screen for any fault (except a video card fault of course)

Did think it was a total loss, but seeing bus activity makes me think it might be saveable.
 
Have you recapped the logic board and the power supply already? Because if you haven't, that's probably why the machine doesn't work. Any Apple machine with the garbage 80s/90s SMD electrolytics needs to be recapped by this point in time.

Look for wetness or brown/yellow stains around the bases of the SMD capacitors on the board, if you see anything then the board needs to be recapped. The PSU should also be recapped because they fail as well.
 
Caps are something on the list but I wonder why the video card isn't displaying anything as it seems its being addressed (it might be duff though) and there is sensible activity on the CPU bus.

Watching a boot of a healthy unit, it looks as if video should start as soon as power is applied so should be activated in the exchange I can see on the nubus i think so either its getting crap, or the card is faulty.

I will try a cheap monochrome adapter and replace the caps but I also need to remove the smd logic chips as one is faulty as I need to warm it up to get the PSU to switch on.
 
You need to replace all of the capacitors before doing any more troubleshooting. The caps going bad WILL prevent the machine from booting. It doesn't matter what video card you use in the system, the results are going to be the same.

It's especially important to recap the power supply, failing capacitors can cause power problems that can damage the motherboard.

I also need to remove the smd logic chips as one is faulty as I need to warm it up to get the PSU to switch on.

This is a symptom of bad capacitors, rarely is it bad ICs that cause the issue.
 
+1 on replacing those SMD capacitors if it's never been done. My IIci was behaving similarly, but replacing the smd electrolytics fixed it. Regardless, it's the first thing to do before looking deeper.

For real. I am one of those guys who is dubious about premature recapping, and I seldom do it unless something is actually broken (and even then only ythe ones that are actually bad). But those smd trashcans that Apple used back then are complete and utter garbage.

Also get rid of the nicad PRAM battery before it leaks. I like to remove the holder and solder in some leads that run to a 3AA holder stuck to the back of the *outside* of the case, so then if something leaks it won't leak on the board.
 
What would be the cost to do all the caps in a IIcx or IIx? Just electrolytics need to be replaced?

A capacitor kit would probably be $30-$35. Going with polymer caps would be a bit more expensive. There's also the option of using tantalum capacitors, but it's not something I'd recommend due to how temperamental they are. Some people swear by them though.

If you wanted someone else to recap a board you have, it'd be whatever their going labor rate is plus shipping. I've recapped boards for a few people here.
 
Both Digikey and Mouser have similar interfaces, but I find Mouser easier to navigate. Less information is thrown in your face at once so it's a lot easier to make decisions on components.

Also Mouser is only around ~220 miles from me so it doesn't take long to get parts.
 
Digikey has changed their site some, but it's still offensive. It used to be you couldn't do anything until yousigned up. Now there's just the odious cookie disclaimer, and no way to opt out. You either accept or exit. They can go strait to you know where. Mouser on the other hand exercises some class and tact. That's where I'll be shopping. Digikey used to be awesome as I recall. I won't even be going back to their site.
 
The cookies thing is to comply with the GDPR law in the EU. Technically any website that is accessible in the EU is required to comply with the GDPR and give notice about what information is stored from whoever is accessing the site, but most people running websites don't comply with it. You really only see it on businesses with an online presence that do business with people in the EU have it.
 
With dk it was worse. The cookies thing you see a lot obviously. Some sights just make it more difficult for you to navigate around the page. And compliance or not, invasive cookies aren't necessary. Because they use them they're obligated to announce. Doesn't make me feel any better.
 
I have a complete set coming from RS for about £20. Fortunately, I have a business account with them and get free next day delivery.

I too dont like just to recap, prefer to diagnose and fix, but it does look as if its a necessary step with these after a bit of reading.
 
Some progress.

All the surface mount capacitors replaced (and the flipflop reflowed) and it now powers on reliably.

It now makes a single chime (a single chord, which sounds very much like the first chord in that 90's intel inside advert) which is the happy chime ?

if I press the NIM button I get what I think is the unhappy four note increasing scale ?

Still no video though.

Looking at the video card its a standard Macintosh display card (4.8 ?), and the lead I am using is set with pin 7 to pin 10 at the Mac side, now will this work with this card ? I can't find anything to say it will or won't but the lead works with my Performa 6200.

The cheap monochrome card isn't here yet to try.

Getting there :)
 
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Cheers for that info

I am using a VGA monitor and for the Peforma the pin 7 to 10 extended sense code works but I was wondering if the card cant make sense of it and therefore not seeing a monitor so refusing to output video.

Will try a different code and see if I get a signal.
 
Some progress.

All the surface mount capacitors replaced (and the flipflop reflowed) and it now powers on reliably.

It now makes a single chime (a single chord, which sounds very much like the first chord in that 90's intel inside advert) which is the happy chime ?

The chime means it is working enough to read the ROM and run the boot code from it. You should also recap the power supply, as dirty power rails can cause the machine to act erratically as well. Another thing to check is the RAM, if you have any bad RAM, the machine won't boot properly either.

if I press the NIM button I get what I think is the unhappy four note increasing scale ?

NMI* Pressing the programmer's switch during boot will cause the machine to crash with either a sad mac or no video, depending on where in the boot process it is.

Cheers for that info

I am using a VGA monitor and for the Peforma the pin 7 to 10 extended sense code works but I was wondering if the card cant make sense of it and therefore not seeing a monitor so refusing to output video.

Will try a different code and see if I get a signal.

Almost all Apple 68k video cards are dumb and always output a video signal, regardless if a monitor is connected or not. The only thing they detect from the monitor is a matrix of a few pins to know the resolution capabilities of the connected monitor. If the video card doesn't a valid configuration, it will default to the lowest setting the card supports, usually 640x480 @ 67 Hz. This is not a standard VGA refresh rate, and a lot of modern monitors have problems with it. You'll usually get an out of range message if the monitor doesn't support it.
 
Almost all Apple 68k video cards are dumb and always output a video signal, regardless if a monitor is connected or not. The only thing they detect from the monitor is a matrix of a few pins to know the resolution capabilities of the connected monitor. If the video card doesn't a valid configuration, it will default to the lowest setting the card supports, usually 640x480 @ 67 Hz. This is not a standard VGA refresh rate, and a lot of modern monitors have problems with it. You'll usually get an out of range message if the monitor doesn't support it.

I can see its processor accessing its rom, but can see no activity on the ramdac which suggests its not being accessed by the cards processor to run the video. It might be duff but I will try tying sense pin 1 to ground tomorrow to see if a valid code would make a difference (at the moment it will see no monitor connected code with pin 7 & 10 connected together and not using the extended sense code method)

Fingers crossed.
 
Well that nails it

Without a valid original sense code the (or at least my) 4.8 card does not output any video signal.

I connected Sense 1 to ground (RGB 15" monitor type) and the display leapt into life :) With a refresh rate of 75hz its well within my LCD monitors capability.

Just need to rebuild the machine now and see if the HD has any life left in it (and strip the floppy, never seen so much crap, its slot must be the major inflow of air to the chassis !
 
Floppy a bit manky

20210402_102832.jpg 20210402_102917.jpg 20210402_102924.jpg 20210402_103033_001.jpg

I can hear the hard drive spin up, then spin down so I think its dead, certainly won't boot. I will have to make some OS floppies, which is a pain as I will have to setup my winXP machine and its far too big.
 
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