I'm a little confused by the telegraphic (short) descriptions that Ethan gives for what he's repaired on and the symptoms of his IIci. (Hint: I think his Mac may be running but it's not producing a VGA-compatible video.) Here's the translation and the gloss to explain it. My read is: the Mac when bought, was dead, no power no video no audio. (Macs "chime", a musical chord, on power up. He describes "chime" but maybe he means "when the power button is pressed to start the Mac".) He then recapped the what? motherboard? power supply? - still no video or maybe no audio. But he says he measures DC power. The 68K Macs (ones with a 68000 series processor), like PCs, operate the power supply from a start-up circuit which is activated by a push-button to the motherboard (mobo) starting circuit. There's a button on the motherboard, and there's also a power key on the Mac ADB-type keyboards (as he describes). There's a way to short two pins on the DC power connector to force the power-supply to "wake up" - Web search for that. The IIci, IIcx and 700 models use the same power supply. Look it up. "screen is black, monitor wakes up" decrypts to "maybe my VGA monitor is showing there's a signal, but it doesn't display it". That may be correct! The Mac has a video connector which needs a quote "Mac to VGA adapter" which mechanically rearranges signals but does nothing to them. The IIci native video, is *not. VGA. compatible.*. The native IIci video (on mobo) however, will never EVER run a VGA only monitor. So it's possible the IIci is producing a video signal. On my Mac IIci, I have a Nubus video card and use that video for VGA compatible results. The Macs "sense" which video connector (on mobo or NuBus) has a cable attached, and route video (and video signal rates) *according to the connector that's cabled up* (which video you connect the monitor to) and select video mode (horizontal vertical signal rates, resolution modes) according to *specific grounded pins on the Mac DB-15 video connector*. The "Mac to VGA adapter" selects those grounded pins. What about the chime? Well, it's common for these Macs to lose their audio. The circuits which produce the audio, tend to corrode out, from both the failing electrolytics PLUS actual corrosion as a consequence of being near the clock circuits. Huh? Well, the Mac time-of-day clock, has constant battery power. That constant DC current creates a galvanic copper rust. Some of that current "creeps" over to the audio circuits. There may be some audio but it may be very quiet. Of course the power supplies fail too, like other switching power supplies. One can research these 68K Mac behaviors on the Web, and Apple had some internal repair diagnostic documents, and "Apple service manuals" per model. Look on the Web for these. But Apple did not document what happens 30 years later; that gets described on the Web by those who repair these things. I don't have much on Mac repairs on my site, I just sell Mac parts, like these. regards, Herb Johnson unexpected Mac geek -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net
I'm a little confused by the telegraphic (short) descriptions that Ethan gives for what he's repaired on and the symptoms of his IIci. (Hint: I think his Mac may be running but it's not producing a VGA-compatible video.) Here's the translation and the gloss to explain it.
Sup buddy! Yea sorry, I type fast. Recap:
My read is: the Mac when bought, was dead, no power no video no audio. (Macs "chime", a musical chord, on power up. He describes "chime" but maybe he means "when the power button is pressed to start the Mac".)
Indeed! No chime!
He then recapped the what? motherboard? power supply? - still no video or maybe no audio. But he says he measures DC power. The 68K Macs (ones with a 68000 series processor), like PCs, operate the power supply from a start-up circuit which is activated by a push-button to the motherboard (mobo) starting circuit. There's a button on the motherboard, and there's also a power key on the Mac ADB-type keyboards (as he describes).
Sorry, recapped the mainboard. The cap leak damage was minimal, no battery damage. I didn't touch the PSU, but I have measured it and everything seems good. This includes the 5v trickle that juices the soft power on keyboard functionality (which works!)
There's a way to short two pins on the DC power connector to force the power-supply to "wake up" - Web search for that. The IIci, IIcx and 700 models use the same power supply. Look it up.
Yea, I didn't need to go there because the power buttons work normally. Can turn it off using the rear button, can turn it on using the ADB keyboard or the power button on the mainboard.
"screen is black, monitor wakes up" decrypts to "maybe my VGA monitor is showing there's a signal, but it doesn't display it". That may be correct! The Mac has a video connector which needs a quote "Mac to VGA adapter" which mechanically rearranges signals but does nothing to them. The IIci native video, is *not. VGA. compatible.*. The native IIci video (on mobo) however, will never EVER run a VGA only monitor. So it's possible the IIci is producing a video signal.
Yep yep! I have one of those Mac DB-15 to VGA adapters. Actually a few of them. And the LCD I'm using which is some crusty 15" thing that clocks to ANYTHING goes from No Signal to black screen when it's powered on.
On my Mac IIci, I have a Nubus video card and use that video for VGA compatible results. The Macs "sense" which video connector (on mobo or NuBus)
Those are sexy! I used to have a bunch of Macs with them (IIx, IIci and others) but gave them all away years ago. They had Radius 21" monitors which were super heavy. Found at a biz Thrift store in Norfolk, used by the Daily Press newspaper in Hampton/Newport News based on the data on the hard drives.
The circuits which produce the audio, tend to corrode out, from both the failing electrolytics PLUS actual corrosion as a consequence of being near the clock circuits. Huh? Well, the Mac time-of-day clock, has constant battery power. That constant DC current creates a galvanic copper rust. Some of that current "creeps" over to the audio circuits. There may be some audio but it may be very quiet.
Battery is in great condition, the audio stuff is all in pretty good condition. Some slight scuzz on the pins of the two SMD chips near the modem/printer ports but I don't think it's bad. Last night I found some IIci schematics, and was kind of surprised to see that the reset button appears to be routed through the Audio ICs? There are two SMD audio ICs, one for left and one for right. The PCB is pretty clean around those. The caps replaced by tantys by your's truely. SOOOOO last night inbetween messing with the 35mm projector that isn't giving me audio... I managed to poke at it a tid bit. I see NO activity on the data bus around the ROM chips. I don't think the CPU is running? I was looking at schematics cause I know the Atari 8bits have some kinda power on reset circuit... So far, all I found out is pin 6 on the audio ICs from the schematics are labelled reset. When I hit the reset button it goes from high to low, then back to high again. I need to hunt down the 68030 reset lines I guess and figure out what state they should be in? Also, I'm at work but I have pics from my phone of my sweet new IIci mobo. This is before recapping but you can see that the mainboard is pretty clean: https://imgur.com/gallery/BlWvimO U83 is the Right sound chip, U-other-one is the other-one. Of COURSE they're propritary. No data sheets from the googles. Oh man, I just noticed in my picture.... RIP nubus connector corner. That will buff out.
One can research these 68K Mac behaviors on the Web, and Apple had some internal repair diagnostic documents, and "Apple service manuals" per model. Look on the Web for these. But Apple did not document what happens 30 years later; that gets described on the Web by those who repair these things. I don't have much on Mac repairs on my site, I just sell Mac parts, like these.
Oooooo service manual you say? I found 3rd party schematics that shed some light on the reset functionality but it seems to mostly be reset-button functionality not any kind of power on reset. There IS a chance that one of the vias is corroded from the cap juice and not passing signal. But none look bad and I ran a few out and they seemed okay? Gonna try to find these troubleshooting docs! Thanks for the hads up on that! I hope it's detailed. - Ethan
On May 12, 2021, at 11:39 AM, Ethan O'Toole via vcf-midatlantic <vcf-midatlantic@lists.vcfed.org> wrote:
"screen is black, monitor wakes up" decrypts to "maybe my VGA monitor is showing there's a signal, but it doesn't display it". That may be correct! The Mac has a video connector which needs a quote "Mac to VGA adapter" which mechanically rearranges signals but does nothing to them. The IIci native video, is *not. VGA. compatible.*. The native IIci video (on mobo) however, will never EVER run a VGA only monitor. So it's possible the IIci is producing a video signal.
Yep yep! I have one of those Mac DB-15 to VGA adapters. Actually a few of them. And the LCD I'm using which is some crusty 15" thing that clocks to ANYTHING goes from No Signal to black screen when it's powered on.
Does it handle Sync on Green? I found out the hard way that the IIci's built-in video is SoG ONLY, which was a big surprise to me. Fortunately, I had one LCD that handled SoG, but it's fairly uncommon these days. The wire-only adaptors (even the excellent Griffin MacPnP) don't convert SoG because it generally requires active conversion and thus has to be powered. - Dave
Does it handle Sync on Green? I found out the hard way that the IIci's built-in video is SoG ONLY, which was a big surprise to me. Fortunately, I had one LCD that handled SoG, but it's fairly uncommon these days. The wire-only adaptors (even the excellent Griffin MacPnP) don't convert SoG because it generally requires active conversion and thus has to be powered.
Hmmm not sure. But I didn't know that the IIci internal only did that. I can ask a friend to bring over something compatible. I used to do a lot with SGI and Sun systems/monitors and a lot of them were funky fixed resolutions at different frequencies and often SoG. It was pretty maddening honestly. Thanks for the heads up on that. I wouldn't be surprised if my 15" Hansol brand LCD can do SoG, it's an oddball and I've thrown 24khz "EGA" arcade video into it and other stuff and it usually works. I *think* the machine isn't thinking because all the data pins on the PROMs are dead on power on. I just see no activity. I got schematics and found the reset circuit loops through the audio chips or something. I see that signal is high until I hit the reset button then it does go low. Was looking for a power on reset circuit that might not be letting the CPU run? That is my "next check." - Ethan
On 5/14/2021 9:13 AM, Ethan O'Toole wrote:
Does it handle Sync on Green? I found out the hard way that the IIci's built-in video is SoG ONLY, which was a big surprise to me.
Hmmm not sure. But I didn't know that the IIci internal only did that. I can ask a friend to bring over something compatible.
I *think* the machine isn't thinking because all the data pins on the PROMs are dead on power on. I just see no activity. I got schematics and found the reset circuit loops through the audio chips or something. I see that signal is high until I hit the reset button then it does go low.
Was looking for a power on reset circuit that might not be letting the CPU run? That is my "next check."
What I get from this response, is simple. "no activity from data lines on PROM" says the CPU isn't likely running - game over. (I presume he's using an oscilloscope, not a logic probe.) I'd say follow the reset line to the CPU reset pin (it's a tiny surface-mount package, hard to probe). You can check the data lines on the on-board RAM. Look at the chip enable on the ROM. Things like that. Looking at fundamental signals - reset, chip enables, general data/address line activity - is a good "cold" approach. As for monitoring the video signals: The IIci/cx will "run" without a monitor connected, that's my experience. So, without a Mac monitor, one can simply monitor the video outputs (say some sync line) for general activity. Possibly a good use for a logic probe, or one can make up a R/C circuit on an LED just as a convenient 'dongle'. While it's possible Ethan can get lucky, and find some opens or shorts; I don't know of a clear path to diagnose other Mac problems likely due to corrosion and spread of capacitor-goop. Any physical fault is likely to be unpredictable, arbitrary. There is likely several and not just one. One would have to be very methodical, to track them all down. But who knows? Maybe the ROM has a POST program that goes to HALT if there's any detected faults? I certainly lack complete knowledge on 68K processors and Apple ROMs. In that particular case, one might replace the ROMs with wired-up IC packages with pullup pulldown diodes to simulate a 68K do-nothing instruction. That forces the processor to run the address space. It's an old-school diagnostic. All that said - it may be, someone who has done a lot of Mac recapping *and* component repair, may have established common faults for that model. But that's a big set of if's. By the way: this is the difference between 1990's computing and pre-1980 computing. With 1980 computing, component level repair *is* possible because most 1980 computers were intended for chip-level repair and contain human-sized components of a simpler nature; and have circuits one can isolate and diagnose. The Macs, all post 1984, were built by robots, with surface mount, on multilayer PC boards. If they were serviced at the chip level that was done "at the factory" and not by service techs in the field. I've seen no Apple documents on chip-level repairs (but I've not looked hard). But that reminds me ... "Sam's Photofacts" were third-party field-service booklets in the era. Checking ... Nope, no Mac IIci or IIcx books, in fact no Mac repair books from Sams at all (samswebsite.com). I'm aware of them for Apple II's and for other consumer computers (C64's and such). What remains, are Mac schematics and repair activities established over time by techs; and "how to recap" activities. To be honest, I've not looked deep on the Web, to see how far those resources can take someone for chip-level repair on Macs. (shrug) if Ethan finds resources I'd like to hear about them, as I work with 68K Macs all the time (but not to repair components for reasons cited). I hope it's useful to discuss chip-level diagnostics and compare-and-contrast in this list. It may be too much detail or tech for some. regards, Herb -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT comcast DOT net
What I get from this response, is simple. "no activity from data lines on PROM" says the CPU isn't likely running - game over. (I presume he's using an oscilloscope, not a logic probe.)
Yeppers. DSO.
I'd say follow the reset line to the CPU reset pin (it's a tiny surface-mount package, hard to probe). You can check the data lines on the on-board RAM. Look at the chip enable on the ROM. Things like that. Looking at fundamental signals - reset, chip enables, general data/address line activity - is a good "cold" approach.
That is what I was thinking. I assume it's toggled on startup but I don't know. I just know that is a thing on the Atari 800XL I was troubleshooting before.
As for monitoring the video signals: The IIci/cx will "run" without a monitor connected, that's my experience. So, without a Mac monitor, one can simply monitor the video outputs (say some sync line) for general activity. Possibly a good use for a logic probe, or one can make up a R/C circuit on an LED just as a convenient 'dongle'.
I tried a floppy disk thinking that I would see it hit the floppy drive in case the sound is bad and I'm not really seeing video. My friend probably has a real Mac monitor, he has a lot of classic Mac stuff.
While it's possible Ethan can get lucky, and find some opens or shorts; I don't know of a clear path to diagnose other Mac problems likely due to corrosion and spread of capacitor-goop. Any physical fault is likely to be unpredictable, arbitrary. There is likely several and not just one. One would have to be very methodical, to track them all down.
On my Yamaha 286 portable, the issue turned out to be the vias not conducting. The traces looked fine but the vias had absorbed some funk from the leaky caps. There is a decent chance it's the same issue with the IIci. But none seem to be that bad. I will have to map out each bad spot and try to figure out it's function.
But who knows? Maybe the ROM has a POST program that goes to HALT if there's any detected faults? I certainly lack complete knowledge on 68K processors and Apple ROMs. In that particular case, one might replace the ROMs with wired-up IC packages with pullup pulldown diodes to simulate a 68K do-nothing instruction. That forces the processor to run the address space. It's an old-school diagnostic.
Over on the Amiga side there is more of a hacker community around the systems and there is a Kickstart ROM replacement called the DiagROM. DiagROM drops in place and then it spits out of the RS232 port a text log as it tests functions on the system. Unfortunately the Mac doesn't have this kind of stuff yet, and if it did it's 4 PROM chips that aren't socketed versus the single or dual socketed ICs on the Amiga.
By the way: this is the difference between 1990's computing and pre-1980 computing. With 1980 computing, component level repair *is* possible because most 1980 computers were intended for chip-level repair and contain human-sized components of a simpler nature; and have circuits one can isolate and diagnose.
Yea. True. It's possible to home swap these chips though. On the Amiga 600 that I was trying to repair the RAM and main chips are all SMD. Hot air and paste works wonders, and if you can get the right amount of paste going it's MUCH quicker to resolder the SMD ICs in! So... don't fear the SMD! The IIci seems like a relatively basic board. The chips are SMD but it's a pretty clean board and not too crazy. The real difficult part is that the power supply humps the main board without any real interconnect, so it's in the way unless you make an extension cable or take it apart and hang the connector out (I haven't done either yet.)
The Macs, all post 1984, were built by robots, with surface mount, on multilayer PC boards. If they were serviced at the chip level that was done "at the factory" and not by service techs in the field. I've seen no Apple documents on chip-level repairs (but I've not looked hard). But that reminds me ... "Sam's Photofacts" were third-party field-service booklets in the era. Checking ... Nope, no Mac IIci or IIcx books, in fact no Mac repair books from Sams at all (samswebsite.com). I'm aware of them for Apple II's and for other consumer computers (C64's and such).
I found the IIci schematics from some 3rd party. Hand drawn, and they're on Archive.org for all. So that is a help. That is where I got the info on the reset, and the oddity that the reset apparently goes thru pin 6 of both audio chips. Maybe to clear DACs or something.
What remains, are Mac schematics and repair activities established over time by techs; and "how to recap" activities. To be honest, I've not looked deep on the Web, to see how far those resources can take someone for chip-level repair on Macs. (shrug) if Ethan finds resources I'd like to hear about them, as I work with 68K Macs all the time (but not to repair components for reasons cited).
There is love for the Mac stuff but it doesn't seem to be as deep or detailed as the Amiga or 8bit stuff. And of course anything I figure out, I will share! It's my goal to make it work again. That is the challenge.
I hope it's useful to discuss chip-level diagnostics and compare-and-contrast in this list. It may be too much detail or tech for some. regards, Herb
No way, this crowd loves that stuff (I predict!) - Ethan
participants (3)
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David Riley -
Ethan O'Toole -
Herb Johnson