VMS70 Fixed Pitch Stablization

[smithadamm]

I'm planning to use the existing 12v to drive the PWM. Just rerouting from the stock system to mine.

Thanks!

That sounds like a good plan, you know the existing 12v system supplies enough current for your motor.

Also, it should be noted that I determined from the I card schematics that the voltage that is pulsed for PWM is rated at 12V in case anyone was interested.

Would you mind sharing that part of the schemo? I would love to to see how Neumann set up their PWM system.

[opcode66]

I will share more as I get it all compiled. I've been doing a lot of research over the weekend. I've come to a number of conclusions.

1. The Zuma pitch computer utilizes the vms tachometers, impulse converter cards and motor drive cards. It is supplying LL, LV and V. The rest is done by the original circuitry. Plenty of zuma owners have great results. So, maybe the tachometers are ok?

2. The tachometer on the Neumann pitch and fast motors are DC. Not AC. That is an important thing to know.

3. I can make a dual extender cable for AS-I1 and AS-L1 cards with an arduino board and simple circuit in between. Powered completely from the lathe. Just simply providing more stable pwm. If I want to use it, I unplug the cards, plug in the cable, plug the cards into the cable, and cut stable fixed pitch.

4. Ultimately, I might be able to get stable pitch by simply making switches in my PS-66 programmer box to disconnect LL and LV. I'm fairly certain now that this will get me where I need to be without much effort. I have a spare programmer for testing purposes. I'm going to try that. I'll report back.

If #4 doesn't work, then I'm going to try #3. I just need to insure that the PID code/circuit will work with this particular DC tacho.

[smithadamm]

I will share more as I get it all compiled. I've been doing a lot of research over the weekend. I've come to a number of conclusions.

1. The Zuma pitch computer utilizes the vms tachometers, impulse converter cards and motor drive cards. It is supplying LL, LV and V. The rest is done by the original circuitry. Plenty of zuma owners have great results. So, maybe the tachometers are ok?

2. The tachometer on the Neumann pitch and fast motors are DC. Not AC. That is an important thing to know.

3. I can make a dual extender cable for AS-I1 and AS-L1 cards with an arduino board and simple circuit in between. Powered completely from the lathe. Just simply providing more stable pwm. If I want to use it, I unplug the cards, plug in the cable, plug the cards into the cable, and cut stable fixed pitch.

4. Ultimately, I might be able to get stable pitch by simply making switches in my PS-66 programmer box to disconnect LL and LV. I'm fairly certain now that this will get me where I need to be without much effort. I have a spare programmer for testing purposes. I'm going to try that. I'll report back.

If #4 doesn't work, then I'm going to try #3. I just need to insure that the PID code/circuit will work with this particular DC tacho.

My tach is DC also, it makes it really easy to get it going. I remember I had to play around with the A/D part of the code, that is to say to get a scale that the PID code liked, I had to adjust the 8-bit scale to incoming voltage ratio.

[opcode66]

I disconnected LL and LV in a spare 33 PS-66 box. I get slightly more stable fixed pitch. Unfortunately, not the stability I need yet. So, a more invasive approach will be required.

[Bonati]

Not to hijack the thread, but a small related detour. If anyone can come up with a drop-in replacement (as much as possible) for the VMS66/70 pitch box motors/tachs you'd have a product that quite a few Neumann cutters would buy. Myself included.