The Haunted Macintosh Color Classic!

[@maxtornogood]

The more you try to fix it, the more it breaks!!

[@gchester99]

Heroic effort - so interesting to watch your diagnostic process (and so admire your patience)

[@tony359]

thanks!

[@alanturing2094]

As usualy, great video! I have a Mac Color Classic that had series RAM issues that took me simply forever to sort out . . . and as soon as that was sorted, the hard drive failed! Oh the joys o retro tech! Thanks again!

[@tony359]

Thank you! Yes, particularly with machines which have been poorly stored and things start failing one after the other...

[@malanvogt]

Great video and how frustrating that board has become. Cant wait for part 3

[@tony359]

Thanks! I hope I can revive it!

[@pepealexandre]

Great video, very educational and entertaining!

[@tony359]

Thank you!

[@bitsundbolts]

I always learn something new watching your videos! Great diagnostic and I can't wait to see the next episode! Good luck to finally find and fix this MAC!

[@tony359]

Thank you Sir, fingers crossed it's nothing unobtainable!

[@vanhetgoor]

It is such a sadness to see an old computer that always did his job faithfully with so little memory. In this day and age it must be possible to enhance the memory till beyond belief. Give this computer veteran a pleasant existence those last few years before his parts dissolve into lose pieces of silicon and metal oxides.

[@tony359]

Will do my best to make it happy again! :)

[@MikesArcadeMonitorRepair]

Excellent explanation, troubleshooting, and rework. I actually let out a verbal "Hey!" when the image showed 4MB at the same time you yelled out "Yes!." Great job. As for the system error and the changing/intermittent issues, I have no doubt you'll get it figured out. We'll be patiently waiting.

[@tony359]

Thank you for your kind words! I hope that too - my concern are the many custom ICs on that board. Fingers crossed.

[@jangoofy]

two thing to look out for when probing digital / high frequency signals: #1: be sure your 10:1 probe is compensated to the scope - most people remember this because it is fun to adjust things :) #2: be aware of your oscilloscope sample rate for the particular measurement condition, it can with ease cause odd signals when it is too low for the expected signals I have no experience with Siglent oscilloscopes, but it just looks a bit weird with the overshoots on rising and falling edges, as low as -3 V. Looking forward to part 3 of X :-)

[@tony359]

I compensated the probe ages ago when I got it - I am using a long ground lead, that is probably introducing all sort of weird things. My Siglent is a 100Mhz hacked to 200Mhz (the probes are only 150MHz I think). it shouldn't have issues with that. But thanks!

[@ArnoldRimmer-d9t]

I am new to your channel, and glad I checked it out after a friends recommendation. Very much enjoyed this video - although I feel for your frustration - and am looking forward to working through your back catalogue!

[@tony359]

Welcome and thank your friends for me!

[@aleksandardjurovic9203]

Thank you ❤

[@tony359]

You're welcome 😊

[@mndx89]

Ciao Tony! Secondo me questa scheda avrebbe bisogno dell’intervento dell’esorciccio 😂 Ottimo lavoro come sempre!

[@tony359]

Ciicccio!! :) Magari la prossima volta invece che un bagno nell'Electrolube faccio un bel bagno nell'acqua santa :)

[@JamesPotts]

Great video, as always. Can't imagine the frustration, though. 😯

[@tony359]

As long as I can fix it, it's going to be ok :)

[@walter7671]

Check the power supply, when it malfunctions it is the component that can damage any part of the system. Sometimes they give dangerous voltage spikes.

[@tony359]

I have unfortunately - I forgot to add a segment in the video. 5V is perfectly stable. No ripple, no nothing.

[@rickchagouri-brindle6520]

Well, I admire your dedication and feel your frustration! My Grandad used to say that if something was easy, then you wouldn'r learn anything from it, so I guess there is always that! I know my Mac Color Classic is living on borrowed time so there may come a time I return to this video for help! Cheers and Ciao!

[@tony359]

It is true: had it been as easy as swapping the Logic Board capacitors.... Yawn! Where's the fun in doing that. As long as I can fix it it's a fun project :)

[@Constantin314]

great video, Tony. now i'm going to see the bluescsi video :)

[@tony359]

I hope you like it - I think it's cool! Almost "main channel"! :D

[@pieroc91]

A good bridge system is a System 7 machine with a network card, using a FTP server and the iCab browser on the Mac you can easily transfer files. I've previously done this with a Performa 630 and ran the server on a modern Windows machine.

[@tony359]

I was told System 9 is ok for a Bridge - does the G4 run System 7?

[@pieroc91]

@@tony359 Well if you already have a G4 i guess that's much better than a System 7 machine, the G4 will not run System 7 natively since it is very old OS. The System 7 machine is very useful if you need to create older MFS 400k disks which are not supported on OS8 and 9. I've read an SE/30 is the ideal candidate for this since it can also run System 6 and ensure full compatibility with older disks.

[@tony359]

I have G3, G4, G5 :) Yes, I don't have the ability to write 800K floppies (didn't know about 400K!) but that's ok I think.

[@sokoloft3]

Awesome! Great work as always Tony. If you make any workshop upgrades in the future I think that'd make good second channel content. I'm currently trying to build a shelf for my work surface to hold my variable power supply, hot air station etc. Trying to keep as much stuff as possible off my work surface. Hooks for tweezers, jumper cables and so on.

[@tony359]

Yes, workshop videos seem to be popular. If I ever tidy up my space, I shall make a video! :)

[@jdmcs]

I noticed that the VRAM SIMM is right beside the on-board RAM. Perhaps this slot and the VRAM SIMM itself warrant a closer look.

[@tony359]

Yes, I now start thinking that maybe the issue has always been the VRAM (or a pad, a trace etc) and I "fixed" things by working nearby! Thanks!

[@hypergl6974]

Altough I never owned a Mac before 2012, I find it really captivating, how you try to find and solve the problems... Maybe someday one of these videos will come handy... ;)

[@tony359]

I never had a Mac! :) My family had an Apple //e. That's also why I am really not familiar with these machines and I am learning as I progress! :)

[@hypergl6974]

@@tony359 my very first computer was a amd386dx with 40mhz and 4mb of ram... It had the most awesome desktop pc case (horizontal one) and in the late 90s I bought myself a creative multimedia kit to upgrade the machine with sb16 and a 4x cdrom... Now I am trying to repair every cdrom I find and soundcard because they are becoming very obsolete 😅

[@sobertillnoon]

like a hiker in the rocky mountains during the fall, you got a ram problem.

[@tony359]

I am not a hiker so I'm not sure I catch the joke! What is the "RAM" for a hiker? :)

[@sobertillnoon]

@@tony359 big horned sheep. Their mating season in the US is late in the year and it makes them quite aggressive

[@tony359]

ah of course! "Ramming speed" in Star Trek :D

[@joelavcoco]

Have you looked into the video RAM? The current video failure could point in that direction, as could previous (video?) freezes, and possibly the yellow hi-lighter effect that you showed after the long RAM test.

[@tony359]

Yes, I was indeed thinking of that. After all it's on the same RAM bus. I cannot find replacements though. But I can definitely look at re-soldering, checking the lines etc.

[@tenminutetokyo2643]

What a score!

[@simontay4851]

I admire your patience and dedication. I would've just said f it and given up. Its not worth the frustration or time. Too many unknowns.

[@tony359]

ahah well, I reached out to the sledgehammer a few times in desperation. :D

[@joelkist6493]

Keep at it Tony you're making headway. 🙂

[@tony359]

Not giving up yet :)

[@SobieRobie]

What a rollercoaster!

[@tony359]

And it's not finished! :)

[@rofbungle8572]

As another user mentioned, it's worth investigating the ROMs. I've had a few of these with failed upper or lower ROMs. Although that would usually mean the system wouldn't boot at all, so it's a long shot (and would be unlikely to be the culprit for video issues). If you do work on the ROMs, be careful with the positioning - they have empty pins at one end. The other thing I have noticed with CCs is that they can be very fussy about system extensions, so experimenting with disabling extensions can help troubleshoot issues (at least by ruling out bothersome extensions). The other issue I've found in these is the ADB IC (341S0417 I think). They can cause all sorts of weirdness and they're right next to an electrolytic - quite common for traces to be corroded under the IC. For video issues it is worth revisiting the logic board. There are two diodes and 1 or 2 resistors next the horizontal drive section that get scorching hot to the point where the PCB starts to carbonize. I usually lift the components up off the board, and replace the resistors with higher wattage. May or may not be related, but worth looking at. Good luck!

[@tony359]

You mean revisiting the Analogue Board? I can take a look. Yes, I noticed the ROMs have an empty row - I double checked on the footage to find out how to plug them properly. I do suspect the ADB chip (Egrit?). It was corroded in episode 1 and when I swapped the keyboard it worked. So maybe either something crusty there or a dodgy ADB. I plan to try the Mac without a keyboard and also to lift that IC and check all traces. Thanks for your help!

[@rofbungle8572]

@@tony359 Sorry - yes the analogue board. It's diodes DL21 and DL22, as well as RF62 and RL11. Worth putting the thermal camera on them as well as inspecting the board. I've seen one of the resistors (can't recall which) getting up towards 120ºC, and the diodes so burned as to be unidentifiable. There are some good threads on the forums about the issue - 68kmla and tinkerdifferent. It's a pain to remove the Egret, but once done it's easy to check the traces. Good luck, and I look forward to the next video - keep up the great work! The thing I've really learned from all your videos is tenacity and different analytical approaches. Very entertaining and informative, and I'm very grateful for all the effort you put into producing regular, high quality videos.

[@tony359]

Interesting - I'll take a look. I worked on that board a lot and didn't notice anything which looked like heat damage but I will double check for sure. What I am told is that because I DO have a grey screen, that should mean that the analogue board is ok. It means it's getting that signal from the logic board. If I had a black screen or a rolling mess, then it's another story. But so far it seems that the Analogue Board is just displaying what it's been sent: a grey screen. Still worth checking those components, thanks for taking the time to look them up for me.

[@bakkus82]

Truly a haunted enigma this one! Maybe you'll end up replacing every single chip at the end? :D It's fun following along here, like your stuff as always

[@tony359]

Thanks! At some point I might end up "firing the parts cannon" at it - though some parts are really not easy to source.

[@cmslick3]

In the first video you adjusted the voltage regulators, have you tried putting them back to the original settings? I wonder if the system was properly adjusted and the voltage is causing the problem right now.

[@tony359]

That's an interesting point - I think it's unlikely but worth checking thanks.

[@stoptheirlies]

Well done Tony that was interesting What low temp solder are you using have you a link please. Bob

[@tony359]

Thank you! I bought it on Ebay, it was sold at measure, nothing special. I think it was just the cheapest available :)

[@willyarma_uk]

Would it work if you simply removed the on board RAM and just used SIMMs? (as a test)

[@tony359]

It's something I thought. I do not know, I think it would. It's just not super-convenient to try! But something to keep in mind.

[@harvaldi]

Did You use contact cleaner on those EPROMs? Did You check if they read correctly on IC programmer?

[@tony359]

Buckets of contact cleaner :) Good point. I haven't tested the ROMs - though the Mac seems to be booting with no picture now, I doubt it would do that if ROMs were bad. Still, a quick test that can be done, thanks!

[@harvaldi]

@@tony359 Literally few days ago I had one EPROM that on every read in my programmer was giving different error. Contact cleaner solved this right away.

[@MarcoGPUtuber]

25:47 Well there's your problem! The RAM Apple used is made in Malaysia, unlike that good Italian RAM. They don't make em like they used to.

[@tony359]

ahah of course! :D

[@itstheweirdguy]

I need to hear "the internet" from you. Thanks :)

[@tony359]

Totally stolen from The Slow-mo guys :)

[@ImogeneRichards]

Tony i feel your pain,tony do you use a logic analyser at all when faultfinding? It really takes the guess work out of faultfinding. If you are able to setup dumps of the cpu accessing lets say the mmu,you can verify that the cpu is getting faithful transfers to,and from memory,also,you can verify mmu register setup by the OS is okay. The other thing you can check,is that I/O transfers are happening properly,and no interface chips are corrupting bits. Logic analysers give you a clear view into all bus activity,i highly recommend you invest in one Tony. Another possibility,write small test programs that you can copy to an eprom,that will run looped tests to the mmu,or other I/O chips you suspect,whilst you flex the board,you can get the program to emit a tone for correct response from the register,for example,and emit another tone if it doesn't read what it had transferred from the register,no analyser needed. Go on challenge yourself! All the best

[@tony359]

That might be a bit out of my reach - I enjoy watching Adrian coming up with diagnostic ROMS which do the basic tasks allowing to diagnose further but I am not at that level I'm afraid. I'm not a developer. A logic analyser could be cool but I'd imagine it must be tricky to set up, it implies a deep knowledge of how the CPU works etc. If there was a diagnostic ROM available, by all means. But I'm not sure I have the skills to do what you suggest, just yet :) Apple computers are pretty "closed". My understanding is that even the onboard "diagnostic routine" hasn't been cracked yet. Thanks for the idea though! :)

[@kyorin6526]

That was a journey!

[@tony359]

It still is :) It's still broken! :)

[@kyorin6526]

@@tony359 I haven't quite gotten to the end of the video yet... About 30 mins in 👍

[@Mediateritorist]

Hey Tony, much thanks for your MCC-Adventure! Perhaps the Mac has a VRAM-issue? Edit: Oh, I just see that @joelavcoco, three hours ago, had already suggested the VRAM thing and you've already responded to it... I'm really looking forward to the third part of your adventure. Thank you for sharing all the frustrating things with us. Otherwise it would be boring - and we wouldn't be able to be so happy for you afterwards :-)

[@tony359]

Indeed - Considering I saw graphical issues as well, I started wondering the same. It's on my to-do list. Thanks for mentioning! Ahah yes, these repairs are the most satisfying - though I am concerned it could be a custom IC which might not be easy to find. Fingers crossed!

[@Mediateritorist]

@@tony359 Yes, fingers crossed!!!

[@adrian_sp6def]

Are You sure that new RAM IC timings is compatible with memory controller?

[@tony359]

Yes, I think it's slightly faster than the original

[@adrian_sp6def]

@@tony359 now You can blame the memory controller since vram and ram has problems

[@tony359]

Well - if a VRAM module has an issue, it might corrupt the RAM bus. Or if there is an intermittent contact somewhere. It could still be one of those 245s. Data lines 16-31 are also shared with the SCSI IC... Lots of places where corruption might happen!

[@uomoartificiale]

I just recently got in vintage Macs and the state of software preservation for the platform is appalling. Most of the software running on system 6 is preserved in sit files created with stuffit > 5.5 which does not run on system 6! And the latest version of stuffit running on system 6 can unpack those! Aaargh It's incredibly frustrating to the point that most threads and discussion online end up suggesting the newcomers to get a bridge machine to unpack the software and transfer it to the target computer. I would even say that the classic Macs are worse preserved than the Amigas.

[@tony359]

Oh, I am so glad I am not the only one experiencing that! When I went to install Stuff-it it was a... STUFF IT archive!!! :D The solution is there but if you don't know it, it's just taking forever. I now have a bridge machine - though the HDD is failing! - so maybe next time it'll be better.

[@rofbungle8572]

I agree. It's very frustrating. A bridge machine is essential. I've been using a G3 Wallstreet powerbook running 9.1 as a bridge machine for many years now. With CDROM and floppy, as well as SCSI and PCMCIA it's like the Swiss Army knife of Macs. A PCMCIA SD card reader comes in very handy too. Oh, and running Basilisk on your modern machine is also very useful. Stuffit drives me crazy, as does the DiskCopy 4 / 6 incompatibilities. The upside is there are lots of options for Macs. I have a lot more difficulty with my Amiga 500s and 2000s.

[@tony359]

I am a Windows person and I can't help but thinking that 2024 Winzip can open a 1992 Zip file :D

[@simontay4851]

Of course it can. I use 7zip and it can open almost any archive file. Stuffit can get stuffed (aka f off). 7zip simply just works. No messing about, it just works.

[@CoolerQ]

Sadly I think the "broken trace that is affected by heat/handling" theory is the most likely :( I would use a scope to look at as many logic signals as possible while the system is running. A broken trace might manifest as another signal that is neither 5v nor 0v.

[@tony359]

I was thinking of trying with hot/cold more. Something that didn't make it in the video is that at some point the Mac was in the "Death Chime" state, I warmed up the board and it booted. I think first I'll inspect/reflow more stuff. Then we shall see. It'll take time! :) Thanks for watching!

[@retroanderson]

Can you do a LC575 next haha. I have one thats dead that I am really stuck with.

[@tony359]

I don't have one! Let me finish the CC first - likely my next project! :)

[@DimasFajar-ns4vb]

action retro last vlog sir and zamzam water

[@tony359]

I'm curious to know what "zamzam water" is now!

[@DimasFajar-ns4vb]

@@tony359 try google or youtube sir

[@PJBonoVox]

You kept saying CAS A. Did you mean CAS B? 😆

[@tony359]

And I had notes in front of me! :D

[@jefftoll604]

Ugh! Intermittent faults are the worse to debug. A second verified working motherboard would be useful in these situations to compare.

[@tony359]

100% - I couldn't get one unfortunately...

[@Vermilicious]

Oof.