gemellocattivo.com

Tonight I ripped apart the new Chinese tach, fixed the a few cold solder joints on the board, ground the board to fit the Veglia mechanism, added a jump because my grinding removed a trace and the tach is working.  All easier than I expected. I'll strip and repaint the face and its ready for the transfers I ordered.

It just occurred to me that the tach doesn't need a circuit board at all. 8 volt zener on the power to the gauge drive coil, other side to the ECU with pwm ground which it already has, same as I have the other gauges working. All the other stuff is to let the tach read a coil signal which it doesn't need to do anymore, so I wasted $14 on the Chinese tach....live and learn.

That's neither the first nor the last $14 you've wasted on this project.

_________________
Wade Williams
Master Ferrari Tech
Restoration Tech
Engine Machinist
Fabricator
Racecar Driver

Talked to the machine shop today, they tried to hone the block but there honing head won't reach the bottom of the cylinders.  We discusses a bit and they will try something else but not until next week and it that doesn't work it will probably come back to me to hone myself....one way or the other it will be back next week I believe.

It turns out the tach doesn't need anything but the drive coil to work just fine...it needs to be cleaned to free up the mechanism a bit after sitting apart for 20 years but other than that its good. I just connected the ground wire and the signal and put a 5V pullup thru a 240 Ohm resistor, the PWM in the cal table it about 92 at zero, 15 at 11k so the resistor is pretty near perfect.

https://youtu.be/k_AThfQcmM4

So this was a lie.  Cleaning helped a bit but what the real problem was, not being an electronics type I don't completely understand but in the 15-25% duty cycle range the mechanism changes how it acts creating a 1500ish rpm dead band.  Tried different frequencies from 10hz to 40khz which move where it occurred a little, tried a capacitor which seemed to make it worse and I final gave up trying to understand it and changed the pullup resistor to send a bit more voltage so I never need to go to the problem zone and that solved it.  I can't believe how much time I wasted on it.

All tis staring at the tach has me, for the 1st time in my life, being a believer in shift lights because now I know better than to trust the tach...it can lag or  it can just be off a bit but the shift light will match the ecu shift point every time.  I'll get the shift light setup tomorrow.....at least as far as the tach is concerned.  Shift point changes with gear selection so I need to add something to let the ecu know what gear is selected.  I remember writing something way back for this but I guess I never finished it because its not in the main program that I used last ti the engine was running.  But Ill get the ECU controlling the brake waring light on the tach as a simple rpm based shift light so I can call the wiring done at least.

Today I thought I'd finally get the shift light setup....that only partially happened. I had the shift light and the exhaust valve to connect and 2 remaining ecu output pins....no wait....where is the 2nd one? gone to coil #11 it seems. I forgot that way the engine lab guys gave me instructions on how to get 12 coil pins when the spec sheet says 10, it cost a HS output pin. hmmmmm.....I was able to rewire the relay panel nd reclaim 1 output.

-Connected up the a wire for the shift light

- Added a wire for the exhaust valve...decide to test the valve....it clicks but doesn't do anything??? fast forward an hour and I realize the little solenoid is switching air ports and the valve itself, a pneumatic valve and needs high pressure air to operate.....DOH! There is a chance I don't need a valve, the vacuum actuators on the valves go at about 5 inhg....decided to leave the wire and see if I need to find a new valve once the engine is running again.

Which brings me to a moment I've been dreading.....wrapping up the wires in the trunk and making it look at least intentional if not neat. It was everything I fear it would be, much like 10lb of **** in a 5lb bag....but it went. Shift light tomorrow.

I'll call the machine shop again tomorrow I guess but in the mean time working down the list.

The shift light is working...of course it says "Brake Failure" not "Shift"....may look for a solution to that before the tach gets reassembled

I relocated the new fuse panel a bit higher to make the cover fit better.

Then it was time to pull apart the steering column to have a look at why the headlight up/down selector was flopping/popping to down and why the wiper switch stalk has been in the door panel since I got the car.

The lights up/down part was just a matter of bending the contacts a bit but ....hmmmm ....old crumpling plastic.....not exactly sure what to do about this....I'm sure a drink will help though.

If you have all the pieces... lots and lots of JBweld.

Alternatively, get back into OnShape and order a 3D printer...