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Q700 ADB or board kaput? Mouse clicks but no movement

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15 hours ago, powermax said:

Please tell us the part number or post a picture...

 

Certainly, @trag and @powermax:

 

It's a Motorola XAA204, p/n FB03. Below is a picture from my other Q700, which I had in front of me at that momen. I was wrong in a previous post, the red claw connects to pin 7 of this chip, not pin 1 (judging by the orientation, marking and drawing).

 

 

IMG_0303.jpg

Edited by pb3623

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It's a Motorola XAA204, p/n FB03

These markings are often confusing and mostly meaningless. If I had to guess, it looks like a Motorola-fabricated clock driver IC (MC74F803), similar to those used in Amiga, see this Wiki page. It seems to provide clocks for the CPU.

You'll find the datasheet MC74F803 for on the above mentioned page.

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1 hour ago, powermax said:

These markings are often confusing and mostly meaningless. If I had to guess, it looks like a Motorola-fabricated clock driver IC (MC74F803), similar to those used in Amiga, see this Wiki page. It seems to provide clocks for the CPU.

You'll find the datasheet MC74F803 for on the above mentioned page.

 

Ahh, brain melting...

 

But seriously, thanks for the link. Could a bad clock driver allow the machine to operate normally, with the exception of certain input registers like mouse movement?

 

It seems this particular chip has a fmax (Maximum Clock Frequency) of 70 MHz, so the chipped 66 MHz crystal should (and appears to be) working fine, otherwise.

 

How do I measure/test the IC? And would I clip it out and run trace wires from the pins to a replacement to test it before soldering? Or can it clip it on top of the existing one?

 

PS - looks like the PowerPump attaches to pin 8 (CP - buffered clock input) so it intercepts the signal coming from the oscillator if I'm reading the datasheet right.

 

Thanks!

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Could a bad clock driver allow the machine to operate normally, with the exception of certain input registers like mouse movement?

I don't think it's possible. It's true that the ADB as a single-line bus requires precise time slices. But this leads to the following logical conclusion: if this timing is somehow broken, the whole ADB communication will become broken. Any partial failure can only happen after the ADB transceiver/decoder, either in hardware (between the ADB decoder and the CPU) or in software.

 

BTW, the mouse you're using, is it a compatible one? Does it work with the other Q700 board as expected?

 

Do you have an oscilloscope/logic analyzer?

Edited by powermax

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I had this issue on a SE/30 once... I had the jumpers on the IIsi pivot set wrong. One of the jumpers on that card switches between two different slot interrupt signals. Keyboard and clicking the mouse were working just fine but moving the mouse around did not do anything.

 

You might want to look if there either is something messing with interrupts on your board or if interrupts from the ADB chip are even reaching their destination. 

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One of the jumpers on that card switches between two different slot interrupt signals.

Yes, I agree. Mouse movements involve interrupt signals. That's indeed smth you want to check next...

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On 3/30/2018 at 3:35 PM, Bolle said:

I had this issue on a SE/30 once... I had the jumpers on the IIsi pivot set wrong. One of the jumpers on that card switches between two different slot interrupt signals. Keyboard and clicking the mouse were working just fine but moving the mouse around did not do anything.

 

You might want to look if there either is something messing with interrupts on your board or if interrupts from the ADB chip are even reaching their destination. 

 

On 3/30/2018 at 3:44 PM, powermax said:

Yes, I agree. Mouse movements involve interrupt signals. That's indeed smth you want to check next...

 

OK - so, along that train of thought...

 

Recall the original issue was due to a bad or flaky Radius PrecisionColor 24 that freaked out the minute I changed resolution or bit depth...

 

Let's say something got messed up in PRAM that couldn't be cleared by pulling the battery or zapping (which is why I thought the TechTool zap was more thorough - but I can't navigate it without a mouse!) - and that, as a result, Slot Manager thinks the NuBus slot(s) are populated or the interrupts are being tied up.

 

Is there a control panel or extension that will reset the slot assignments?

 

I don't know much about "legacy" (pre-OS X) AppleScript - but could someone script TechTool to launch on startup, zap the PRAM and restart? Hence, mitigate the need for a working mouse?

 

PS - powermax - yes, they're legit and working Apple ADB mice that work in other machines.

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Let's say something got messed up in PRAM that couldn't be cleared by pulling the battery or zapping

This would be possible if your board had EEPROM or Flash storage. It's a well-known fact that all Apple desktops in the 90s use 3.6V lithium batteries to maintain non-volatile memory. That means that PRAM (NVRAM) is actually a small amount of CMOS RAM powered either by the mains or the battery. In the case ALL power is lost (that's it - the battery was pulled and the power supply is off), the whole PRAM content is also lost. It's difficult to imagine what kind of magic TechToll can do beyond that...

 

FYI, PRAM is a part of the RTC IC (U92). Its part number is either 343S0042 (Motorola-made) or 344S042 (VLSI-made). I don't know which one sits on your board...

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Thanks for the info. There were a lot of Moto chips on it when I had it open over the weekend. I keep bringing up TechTool because the Zap from within the app fixed a previous issue I had with this video card (which, back then, only caused a problem with booting, not ADB)... an issue that pulling the battery and unplugging the mains didn't solve - like hours... but maybe hours wasn't enough and it needed to be left overnight. At this point the board has been sitting since Sunday without power or battery so if it's still messed up, do I try to acquire replacement RTC and clock driver ICs and piggy-back them? Or replace them outright? The whole unit is in really nice shape and I would like to have a working spare or entertain the thought of selling it.

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do I try to acquire replacement RTC and clock driver ICs and piggy-back them? Or replace them outright?

Frankly spoken, I'm out of my depth now. I think you need to gather more data on the failure of your Quadra board. Can you do some electrical analysis of your board and compare the signals it generates with a known working board? That would be very helpful. Otherwise, we won't be able to go a step beyond guessing.

Moreover, I don't think that any blind IC replacement would be a good idea, especially when the ICs in question are vintage ASICs you'll probably not be able to find any replacement for...

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Unfortunately, you're reaching the point where  you just about need an oscilloscope at a minimum to continue testing.   A logic analyzer would be better.   If this was a common problem then the most likely solution might be none.  But for what amounts to a one-off problem, actual electrical diagnoses is probably necessary.

 

You could identify all the chips involved in the ADB bus, get a working Q700, and trade them one at a time, until the problem moves from one machine to the other.   That's assuming that all your soldering is good.   It's very tedious.

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Thanks for the candor, everyone. As a last-ditch measure, I installed the Easy Access cpanel onto my 7.6.1 partition on my working Q700 and tested Mouse Keys by (IIRC) Shift-Opt-Cmd-Clear... on the bad Q700 I can enable Mouse Keys (the up-sliding beep) and can use '5' on the numpad to click but can't move... so emulating mouse movement isn't even working (and it's not software because I took the whole SCSI2SD out of my working machine)

 

I don't have an oscilloscope or logic analyzer, and even if I picked one up for a song, I'm wondering if it wouldn't be worth it just to pay someone to check it out at an electrical level.   

 

And no, my soldering skills resemble those of a 5-year old - I lack the experience and right equipment to do a proper job but unless someone wants to crack at it, this might be the perfect board to train on...

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I feel like we might be missing something easy.   Larry Pina wrote a bunch of books that had helpful sections of the form, "If X is wrong with your Mac, replace Z or resolder Y".    I don't think he ever did a book for a Mac as late as the Q700, but since it isn't using Egret/CUDA yet and still has distinct VIA 1 and VIA 2 chips, I think its ADB subsystem might be analogous to the older machines.

 

I know there was/is a PDF version of "The Dead Mac Scrolls" kicking around, but I can't remember if it covers the SE (earliest? machine with ADB bus).  He also had a series of books of the form "[   ] Repair and Upgrade Secrets", where the first one was Macintosh, but there were later books for the SE/30 and I think for the Mac II.

 

I would check one or more of those, the ones that applied to ADB Macs, for the symptom you're having.   

 

You might also take a look at "The Guide to the Macintosh Family Hardware" or perhaps, the appropriate chapter of "Inside Macintosh" and see if there's  something fundamentally different in how the ADB bus handles keyboard input vs. mouse input.      The symptoms of your problem are very strange and I feel like it should be pointing us right at something, but my knowledge of these systems was never great, and my memories are old and leaky.

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@trag There is a distinct book that covers the SE and Classic: http://maccaps.com/MacCaps/Repair_books_files/Mac Classic %26 SE Repair and Upgrade Secrets.pdf

 

Not sure about the Q700, but the very end of the Mac II book might cover it (link), as it isn't too different than a IIci basically, at least in terms of form factor.

 

c

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Thanks for the links, @trag and @CC_333. There's not a whole lot of Iici-specific content in the last link to the Pina Mac II book and even less for troubleshooting ADB, but it seems like I'll want to check out the 4-pin EMI RFI board filters that I think are the black cubes with what I describe as having 4 staples (L3 is the filter parked behind the ADB ports)

 

I'm attaching some photos in case someone with better eyes sees anything obvious. The polyfuses (F3 in particular) look good/closed and I'm just not sure what else could have gone bad.

 

Thanks!

 

https://imgur.com/a/WzX3o3W

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