AMC401 - No Tach - Now with 36-1 + Hall

[yossarian19]

So, I threw up my hands in disgust at my inability to get coil-negative tach to work. Hell with it, I said, I'll send this box to a pro and while I'm at it, I'm going waste-spark, hall sensor, and MapDaddy 4 for better altitude compensation. The pull-up resistor for 12v operation of the hall sensor was put in the case, too.
Note that I haven't opened the case (yet) to verify - I'm taking it on faith and reputation that all is at it should be so far.
The pro said that he made all needed mods for a threaded body sensor + waste spark but that the tach signal continued to give fits until he re-loaded firmware and used a new MSQ file. Something was corrupted in the files / firmware, it would seem, but it worked just fine before he shipped it back to me.
Now, I have no tach signal at all.
Hall sensor is 0.95 mm from the wheel, centered on it pretty well. Black wire on sensor is to the shielded white in the harness. Tan wire on sensor to 12v. Blue wire is to the sensor ground bus.
With ignition key on, I have 4.8 volts on the signal wire. Cranking, my DVM won't keep up but it reads 1.9 which is what I'd expect. Sensor ground reads, well, grounded.
So, any ideas?

[rickb794]

So no RPM indication in TS?

Tooth or trigger log?

any Sync Error # indications?

[yossarian19]

I get a "0" in TS, don't see anything at all on a tooth log. Voltage at signal wire reads 4.8 // 0 as I manually turn the crank.

I didn't see the sync loss needle moving, for what that's worth.

I need to record a data log and will do so but I've somehow created one of zero bytes, so evidently I forgot somethign since the last go-round.

[yossarian19]

Update:
it's set up for VR input (VRin --> Tachselect, Tsel --> VRout) with tachselect / VRin wired with a 2.4k resistor in the proto area, other end of which is in the 5v slot. (edit: ok, this all appears correct per manual) so that's good news, I guess the only variable I can see there is if the trim pots are adjusted right.

D2 and C30 are still installed from a previous iteration where I was tyring ot run coil negative... this isn't right, is it?

[DaveEFI]

D2 and C30 are pat of the opto input. Won't make any difference to the VR input.

[yossarian19]

Hmm. Well. I'm about out of ideas why I have no tach signal, then.
What am I missing?

[yossarian19]

IT RUNS! Holy hell I didn't think I would be this excited but I'm chock full of STOKED. I popped the lid, verified (slowly and with help) that all was as it should be, turned R56 all the way back then ~6 turns forward, started a new project file & it fired right up.
Thanks to everyone who's offered help, both this go-round and last - I wouldn't have done it without you folks.