Very odd SE/30 ADB issue

[DannyDorito]

This is an odd issue:
On my SE/30, recently acquired and recapped, everything works fine up until you try to use peripherals. If there is a mouse plugged in, the machine will boot but the mouse is slow and jitters, no matter the surface, even if manipulating the rollers manually. If there is a keyboard plugged in (Apple Keyboard II in this case, works fine with every other ADB Mac I have) then it hangs shortly after the "Welcome to Macintosh" screen. Unplugging the ADB cable will immediately allow the boot to continue. I'm booting from a 20SC in this case as the internal HD is dead and no HD20 support.

I have not observed this on any other machine, and I know both peripherals are good. Happens with both of the ADB Mice I have, too.

 

[GRudolf94]

A tentative answer is "there's still cap crud from somewhere sitting on the ADB dataline".

 

[DannyDorito]

My thought too, guess I need to hop back in and check the ADB controller. Just thought I'd check and see if anyone has had this issue, whether it's with the software or hardware side. The boot hanging is what confuses me there.

 

[GRudolf94]

Yeah, that would suggest something wrong with the system bus<>controller side of things, not controller<>peripheral, but who knows. I'm assuming the mouse acts weird even not booting off the 20SC? That would eliminate software.

 

[DannyDorito]

Yep. Although interestingly when booting to the system 7.1 installer from floppy emu, it boots successfully even with the keyboard connected. It doesn't do this for something like disk tools... how wonderfully inconsistent.

 

[DannyDorito]

Found that the negative side of C13 had not been soldered on. Curse whoever did the recap! Oh wait... Checked all other caps and while my soldering work isn't the best they are all making contact and secure.

Didn't help the ADB issue, but the light on the internal HDD now lights up on initial startup. Still dead though, I believe. The mouse moves, slowly, and only somewhat useable in cardinal directions. The ADB lines look clean, I guess next I'll be dissecting how ADB works in order to see if there's garbage on the signals on the data lines. I was wrong about the system 7.1 installer booting as I accidentally had the keyboard unplugged. With it plugged in, it suffers from the same issue, randomly stopping during boot. How strange. Pressing the interrupt switch causes the box that would usually appear to flicker wildly and eventually stop, leaving the machine completely stuck after oddly trying to read from the floppy? I'm beyond confused.

 

[DannyDorito]

Probing the ADB data line I can see a stream of data, although things don't look good. Without the keyboard or mouse attached, everything has nice, 90 degree corners. As soon as I attach the keyboard, the waveform becomes jagged, although still has the same data. Pressing keys predictably does nothing. Using the mouse results in a clean signal, but the sync (?) seems to be off somehow. The scope locks on just fine without anything attached, but connecting the mouse seems to pull the signal in an odd way. The data burst jumps around and the signal in between is jagged rather than a smooth line like without the mouse. Clicking does change a couple of bits visibly, and so does moving the mouse. Could this be interference? I'm using a shielded S-video cable between keyboard and computer, so interference should be minimal. I may be using the scope wrong, but it certainly changes something.