Why will this Macintosh IIci not work, HELP!

[@CRG]

At the end of the video I mentioned that the databus is falling over but never gave much explanation. Looking at it with my scope, all signals are fine at startup, but maybe 1-2 seconds after the chime the signals are corrupted, it looks like it's trying to pulse but getting pulled down. Another possible clue is that with the HDD reattached at the moment of the crash it's almost like the power drops out for a split second. The drive restarts almost like you had flicked the power off/on. If anyone has any ideas as to where to look next I'd be extremely grateful. I've tried reflowing most of the main ICS. The via has been off to check for damage but it's fine. If there is any interest I can pull together a quick 5 minutes video to show what the bus is doing.

[@simontay4851]

If you think the power is dropping out for a split second, check the ripple on the 5V rail and the caps in the PSU.

[@moshly64]

I think the picture you took is the clue. I don't know how the video works (looks like it takes from system ram) but those lines look like they are repeating every 32 pixels ? And it looks like it starts on the 4th pixel ? Maybe data bit D3 has a problem. (or maybe D3 and another signal that happens to be working for this boot) Also, a tip for probing with the scope: Try to find the signal you are checking on the last chip in the chain, don't just check it on the rom or cpu as it may look ok but may not be reaching everything it should. Also continuity check the same way, every node. I had 2x c64s that took hours to track down open r/w lines on the dram (if only i'd scoped the last row), I only found the faults once I did a 100% point to point continuity check.

[@Otakunopodcast]

I have no idea what that edge connector is for. My SE/30 logic board has one too. But neither the SE/30 nor the IIci have a mating connector in the case. Pretty sure that the Color Classic is the first Mac that actually has a logic board that plugs into the chassis. My best guess is that it is some sort of debug/test header, so that they can test/debug boards at the factory. Traces that apparently come from/go to nowhere are probably going to an internal layer of the board. All Mac boards are at least four layer, which makes fixing them much more difficult/challenging. Internal traces could be damaged and/or some vias may have connections to internal traces that got compromised. You can somewhat see the internal layers if you hold the board up to a strong light source, but to really see everything you would need to desolder all the components off the board (because you don't know if any traces go underneath components.) There are IIci schematics out there (I believe they are reverse engineered by the community) so that might help. There are definitely people reverse engineering and creating new Mac boards. I know they already exist for the SE and the SE/30. Not sure if any of the Mac II models have yet been RE'd into community created PCBs yet. I'm sure someone somewhere is working on one tho, so it's only a matter of time. One thing you might want to look into is a pair of ultra sharp multimeter probes. They aren't really that expensive (I think I got mine for US$8 or so.) They make probing small traces/vias like this alot easier. Probing such small things using standard multimeter probes feels a bit like performing brain surgery with a steak knife :)

[@elfenmagix8173]

Look, you got a working Mac. Despite what you are seeing, the mac is working. Or else it would not Bong and give tones. Possible Issues: The Mac IIci is a bit FUNKY with its Video Port. Make sure you have standard VGA with Sync on Green for 640X480 resolution. If not, you will always get a black screen on any video capture set up or even on a VGA Monitor. This also happens on the Mac LC/LCII and Mac IIsi. Things you do have wrong are: The RAM is on the wrong Sockets. They need to be on the left-most side of the board. It would be best if you have 1MB simms on the left side and 256KB simms on the right. The Mac IIci and IIsi takes RAM from the simms you put in to use for the video; on the IIci, the Right-most side is usually where the RAM is taken for video, but if there is nothing there, then it takes it from the left side. The Left-side is where bottom of RAM is and fills up accordingly with the right side adjusting to it. You did well with the repair. It giving you a Bong without other noise codes (musical tones on the Mac II Series), means that the Mac is working. Just move over the RAM and add the 256kb to the right side. The rest is figuring out the video, which is hard to do on the IIci, IIsi, LC and LC II series. If you have one of those Mac to VGA adapters, it would help greatly. Use it and go through the switches on the adapter while the Mac is on and eventually you will hit a spot where you will get video on the screen. The Black screen is saying that the monitor is not set up correctly for the Mac IIci's video output. Good Luck. I know you got it right.

[@esseferio]

about the vertical position, your guess is absolutely correct :)

[@CRG]

I think if I get this one working it'll be displayed in its vertical orientation 🙂

[@simontay4851]

You have a lot more patience than i do. If i saw that amount of battery damage, I wouldn't have even started - especially for something this old.. Stick it on the wall and move on to something else that you know you can fix.

[@CRG]

There have been a few good suggestions in these comments that are easy enough to test so I'll try those then just put it away and wait for someone to release a new PCB for it. Apparently its being worked on.

[@paulklasmann1218]

Where you see micro vias appearing not to go anywhere, they are going to buried vias or to a power plane in the multilayered PCB. They do go somewhere.

[@CRG]

I wonder if that one point then could be an issue. There is certainly internal signalling in this board, that's shown on the schematics and if that one point I showed in the video has indeed delaminated internally well, that could spell game over. Perhaps the one time it booted it somehow made connection. Maybe if I could clear it out, feed a small wire into it and flow a lot of solder it might restore any broken connectivity🤔

[@paulklasmann1218]

@@CRG you could try restarting while flexing the PCB in different ways or if you suspect that via path you could bypass it with a wire if you check the scematic to see where it comes from or goes to. If you can follow the trace to where it connects to a component first then check the schematic to see where that net goes to, to do the bypass. Also too much heating with hot air and no preheating can cause problems with buried vias and traces.

[@Shmbler]

I put all my bets on another broken trace or detached pad. I've had floating inputs cause spurious signs of life before. It doesn't have to be in the corrosion area. Also, you might try heating up or freezing down various areas of the board to see of you can change the behavior. I've had hopeless cases like that before and put them away after spending way too much time. A year or two later I checked them again and found the issue quite quickly.

[@CRG]

You could well be right, the problem with something like that though is finding it! I suppose if anywhere its likely to be around the capacitors, might be worth giving those areas a second look.

[@adonisnetworks]

Most old macs needed a new 3 volt pram battery installed to get the pram to function correctly, if these went flat the Mac's wouldn't boot properly .

[@patrikaxelsson7789]

Great effort, admire your energy!

[@olepigeon]

An excellent attempt. In regards to that capacitor you knocked off, well, _ALL_ IIcis need a recap. But you seem exceptionally knowledgeable, so I'm certain you've already deduced that. I'm surprised that cap didn't take the pads with it. Every single one of those capacitors will have vomited all over the board. Not to mention that many had Maxell batteries that just crap themselves, destroying many vintage Macs. While the IIci is one of the best compact 68k Macs with its generous 3 NuBus slots and easy 68040 upgrades, it unfortunately is pretty notorious for repairs. My own IIci is down for the count. _Something_ is shorting the 5v rail to ground and preventing it from booting, but I spent so many hours trying to troubleshoot it that I eventually gave up. By the way, there's an open source ATX to IIci adapter. Costs maybe $10 to build one. It even includes a voltage inverter so you can still power on the machine via the keyboard. Coupled with an ATX extension cable, it makes it super convenient and easy to diagnose a IIcx, IIci, IIsi, IIvx, IIvi, Quadtra 700, Quadra & Centris 650s, and PowerMac 7100. It also rules out the power supplies which are also failing due to bad caps. Man, the 1990s just sucked for quality components.

[@CRG]

The board was recapped by the previous owner and I'm confident that he did a decent enough job. Granted he missed soldering that one side of that cap but we've all done stuff like that. As for knocking off the cap I can only assume the other solder joint was weak and so dumb luck I didn't knock off a pad at the same time. In fact just writing that is making me think I should at least reflow all the other caps just incase there is a bad joint I've missed. The psu is one thing I haven't looked at yet but I really should. A full recap of that is probably needed. The issues might be power related. I've got a few ideas from comments for things to try so there will be another video at some point and fingers crossed I can get it going.

[@olepigeon]

@@CRG My apologies. I skipped directly to the repair part, so I missed the intro about it being recapped. That was indeed lucky.

[@Ragnar8504]

The bottom LED is power (green), the top as you guess HDD activity, orange. Out of the three IIc(x) models (two IIcx and one IIci) I've played around with the HDD LED was only present in one, the other two had been removed. The three axial electrolytics look original to me. I seem to remember reading they're part of the soft power-on circuit and can cause problems with that. One of my IIcxs probably had issues there. One night it decided to turn itself on (scaring the living daylights out of my parents when the After Dark screensaver started talking, I had Bad Dog on that computer) and simply wouldn't turn off anymore. Select shut down from the menu, system powers down, only to restart immediately. On the far right ROM chip (25:15 into the video) I'm surprised the trace between pins 11 and 12 (going to the other row of pins, pin 27 if I counted correctly) isn't broken, it looks quite suspect just where it angles up!

[@CRG]

I double check that trace but I have buzzed everything out from the roms to positions further up the board and they are fine. The soft start feature on my board still works, I didn't show it in the video but I tested with a keyboard attached. I'll see if I have a green LED and will swap that yellow one out.

[@Plan-C]

Great video. I know it is a very low tech approach but have you tried tapping / applying pressure to different areas of the board to see if the behaviour changes at all? It could be a via or trace that is just about touching when the board is a certain way. Had it with an Acorn machine that had a lot of battery damage. It worked on the kitchen table but when I moved it to the telly in the front room it stopped 🤣. It is maddening. Especially when you were about to give up and it teased with a glimmer of hope with that screen. The VLSI chip is quite close to the damaged area to. Are all it's pins firmly connected? Maybe one is a bit flakey or the metal has gone to crap with the battery acid? Enjoyed the video.

[@CRG]

I did try flexing the board or pressing on certain parts of it while resetting to see if it did anything. Didn't bother showing it in the video as it did nothing but nothing wrong with the low tech approach. Sometimes the simplest methods yield the best results.

[@jdmcs]

In no particular order: Your IIci is behaving very similarly to my IIci that I tried to repair in a livestream last year. The only difference is that I never saw the white screen. It's possible your board has another broken trace near the soft power circuit/RBV chip. (The RBV chip is the video chip.) In my case, I suspect that my RBV chip failed. The RTC chip is probably required because it also holds the Parameter RAM (PRAM). In fact, per previous experience, the Apple ROMs pretty much expect the board has all the major components on it. You could probably remove the serial transceivers and the FPU and it would start to boot the System software, but System 7 will hang if the former is missing and the System software will throw an F-line System Bomb at some point if the latter is missing. The fact that the chime and death chimes (that jingle you hear when you press the Programmer Switch because there is no debugger loaded) are playing correctly, is a good sign. It means the system is able to read the sounds from ROM. That being said, you don't need the battery to power the IIci on. IIRC, the missing LED (DS1) was a green power LED.

[@CRG]

Thanks for the info, I'll double check around the video chip and see if I can find any damage. My comment about removing stuff would just be in an attempt to try and stumble into the cause of the fault. Not exactly the most scientific approach but sometimes needs must. I'll keep this as a last ditch effort but there are a few other things to try first.

[@Ragnar8504]

AFAIK no Mac actually needed a battery to boot but some specimens across various models (with absolutely no rhyme or reason) act up without a battery, showing only a black screen. Leaving them on for a few seconds and then doing a soft reboot usually fixes that and gets them to boot normally. Actually, any way of rebooting except disconnecting power will work. Some models were more prone to this behavious (Performa 475 among others), some less but I've seen it across a whole list of 68k and PPC models. Back in the 90s even some repair shops would diagnose a flat PRAM battery as a dead logicboard, which was pretty painful for the customer.

[@arioch2004]

On the rom chip socket where you fold a leg over, measure it and says "it is fine", I can literally see the broken trace still. You do not have a connection between the bent leg and the other trace. So you measured a connection somewhere else.

[@CRG]

Sometimes it looks like it's broken but in fact it's fine. This board has since been repaired, it went to another guy who found a further damaged trace at the far end of the board which brought it back.

[@Stjaernljus]

it chimes so it can't be that broken. would check so clock and reset lines reach where they should, especially on display related chips/components.

[@CRG]

I've checked clock and reset to those components I can access and its fine. One issue is with the way the PSU mounts is that it covers half the PCB making it very difficult to test some components while powered up.

[@GeorgesChannel]

I admire your patience endurence. I have no ideas. Maybe you could try to attach a working floppydrive oder diskdrive to it. maybe it will boot again

[@CRG]

Good idea and I have tried that off camera but unfortunately it doesn't boot. There are a few other suggestions in these comments so plenty of other things to try before totally giving up.

[@Stefan_Payne]

Have you looked at the Board, if you see some "Layer Markers"? Maybe this Board is a 4 Layer Board and some traces inside the Board are damaged? And it worked that one time because it was bend just in the right way that the damaged trace made contact?

[@CRG]

The schematics show that the board does indeed have multiple layer with internal signalling and not just VCC or Ground. If it is an internal failure then I might be beaten, would be hard to find such a problem. I have checked continuity of all pins from the roms up into the board and they are fine but there very may well be something else damaged.

[@CheshireNoir]

Maybe reach out to Bruce (Branchus Creations) Rayne for assistance? He's got a serious amount of experience fixing this era of Macs.

[@CRG]

Not a bad idea, I've seen a few of his videos on Macs and he does seem very knowledgeable.

[@Fred_le_lorrain]

Beginner's question, have you checked the regularity of the power supply? the voltage may drop after a few seconds.

[@CRG]

I did check the voltage levels and they look fine but it might not be able to sustain the current and dropping voltage as you suggest. A full recap of the PSU is probably required any way, I just need to order the parts!

[@neuro_davinci]

Just a thought, I have worked on finicky old boards (not macs), and when the issues are this intermittent, I have checked all the vias. Sometimes they connect and sometimes they dont causing this exact issue.

[@CRG]

Could be a via, good suggestion. I'll be sure to double check those in the corrosion area.

[@brynjarborgersen8131]

My first thought, seeing as you got the sad mac once...... work backwards from the display plug and check continuity? Might be a bad solder point somewhere between display chip and monitor port? IF you get a steady sad mac screen, it should be a "simple" case of bootable media from there onwards

[@CRG]

I'm going to over a proper vga converter for the output, just to 100% rule out that its not my homemade cable although I'm fairly sure its not. But yes beyond that, good suggestion, I'll take a closer look at the display chip and related circuit.

[@Stefan_Payne]

A Retro Chip tester Pro might have helped you a lot in this endeavor, wouldn't it? :)

[@CRG]

Probably would have but they are not the cheapest thing at £185 for a full kit on eBay. I just need to save my pennies to get one.

[@skeggjoldgunnr3167]

Those yellow tantalums are horrible. Their failure mode is a short. In coupling mode that will bring down a power rail. Not saying that's your problem, but 'since the days they were chosen here that was due to their size / density benefit - today's electrolytics are much smaller than they were back then.

[@CRG]

I did test the board for shorts, certainly no dead shorts although 5V to Ground is only about 15ohms 🤔 I'll ask another owner to test their board to double check thats correct.

[@bitsundbolts]

Hi - I am no expert, but maybe it is "bit rot". Over time ROM chips may get faulty or lose the data stored within them. I had a PCI graphic card that would POST when installed, but there was no video output signal. I was able to recover the BIOS from the card and compared it with the original binary file - 4 bits were different. What I am trying to say is that maybe this random behavior is from a faulty ROM chip which may deliver random values (and by accident delivered this one time a correct value when the board booted). Maybe from 100 tries, it will work once. I am working on another Geforce2 MX card which seems to suffer from a similar issue, but no details yet.

[@CRG]

That thought had crossed my mind, there could be a failure in the roms further into the code. Its running to the point where it chimes then the roms are corrupted. As I said in the video though I'm not sure I can read these out easily in my TL866. I might see if I can borrow a known good set of roms from someone to test with. If that was the issue I can disabled the roms and use a rom simm instead. Also just wanted to say I've been following your work on the voodoo cards, great video series. Keep up the good work its been fascinating to see.

[@georgeaiaskaridis5812]

Very nice work! What about that R83, was it ever there? What about the traces around the via below it. (28min 26sec) Looking forward for another video on this board.

[@CRG]

I don't believe R83 was ever installed but I'll double check the schematics. I've got a few good ideas from comments here so will give those a go in a follow up video.

[@wdd6864]

I would reach out to Mac84 at his email and see if he can give suggestions. Huge Mac Fan

[@CRG]

Yeah not a bad idea, might be worth a chat with him 👍

[@michaelsworkshop9031]

Did you check that the power supply is putting out proper voltages (and enough current) ? Do you have a different (known working) IIci power supply you can swap for this one, or a known good mainboard you can try with this power supply? Those moments of it working, then stopping, and then for periods no longer working, sound like an issue that changes after heat or voltage, not a permanent one like broken traces or bad chips would cause. Despite all the damage to the board you found and fixed, I would rule this out now after all those board repairs you made before going any further.

[@CRG]

I'm starting to wonder myself if the PSU is at fault. Its certainly putting out a steady 5v and 12v but there is nothing to say it is stable. A recap of the PSU might be in order. I unfortunately don't have another IIci to compare against, I don't have much in the way of MAC stuff to be honest.

[@michaelsworkshop9031]

@@CRG I would want to rule this out - maybe theres a friend or community member who can loan a known working power supply. I just solved a problem myself this week where a (different) device's power supply measured 5v on the multimeter but wouldn't actually power the device - wasn't putting out enough or any cuurent needed. It would not surprise me that despite all the board damage, there's even more damage or failures inside the power supply.

[@Ragnar8504]

@@michaelsworkshop9031 I'd even go a step further and say I'd be surprised if there weren't any problematic caps in the power supply. I haven't plugged in most of my vintage Macs for a long time but I've definitely had problems with bad caps in AT power supplies. One caused the most amazing psychedelic graphics glitches in a Pentium 1, I think most of the picture was still there but the colours were all sorts of crazy! Then the picture got garbled as well and I turned the machine off as quickly as I could.

[@PaulinesPastimes]

A wise decision to just put it to one side and let it fade away for a while. You sure tried. Maybe you will think of a solution to it, or it could just end up screwed to the wall for spare parts. 👌

[@mistwolf]

My two instincts from an utter incompetent amateur who has never touched a vintage mac would be something in the video circuitry, either a broken trace or maybe an encoding issue, but it seems to be working outside video? is there some kind of command line in prom that you could do anything in just to see if it is working outside video? or maybe try a period-appropriate monitor if you can find one, maybe it just doesn't like whatever conversion it is? I mean I have no real clue, just thoughts of what i'd try in your place

[@CRG]

I've tried connecting a HDD and floppy drive but the system doesn't try to boot from them. I'm fairly sure there is a fault somewhere and its not just video but I'm going to order a proper vga adapter and double check the video circuit just to be sure. I have tried an Apple CRT and it behaves the same, the CRT is just to big for my desk hence why its not in the video. Of course there is nothing to say my CRT is compatible with the IIci.

[@enzofitzhume7320]

Re-cap!

[@pb7379-j2k]

Yes all those electrolytic surface mounts are not to be trusted

[@CRG]

It has been recapped.

[@eai554]

Hhmm, in its heyday, the IIci was a great computer; but times have changed, to say the least. Why bother?

[@CRG]

I was in the middle of working on my next project when you made your comment and it did make me sit up and think for a minute, why bother... Well, the only answer I can come to is why not. It's a hobby, it's something I enjoy doing. Yes, it takes hours and in this case I may never get the system working but I do ultimately enjoy working on these old machines. I may get frustrated at times, that's only natural, but people collect and restore all sorts of old junk so why not old computers?

[@PaulinesPastimes]

@@CRG Whatever makes you happy I say. With me it vintage Tri-ang. And vintage computers of course!

[@miked4377]

dont know if thats even worth fixing after every thing you have done......a plus for effort crg...that board is anightmare cause of yhe damage....

[@CRG]

It certainly is a nightmare and I was close to giving up a few times but there's been a few good suggestions in the comments here so a few more things to try before I truly give up.

[@timcross3461]

Well, it is only a Mac... 😂

[@CRG]

This is true but supposedly the IIci is one of the better Mac's. Plus it's so close to working, I'm sure it's going to be something simple that I've overlooked.

[@timcross3461]

@@CRG I am using some corroded Amiga A501 cards to test this restore method. Great information in here!

[@timcross3461]

Seeing those plastic clips on the SIMM slots is so aggravating...