Denford VMC1300 - Rescued

**m_c** · 17-01-2019

Originally Posted by Clive S

I have just converted a Novamill that seems to have had the same control board. I used one of these https://www.ebay.co.uk/itm/111654184682 and a small 230V ac to 15V V DC power supply https://www.ebay.co.uk/i/26304063959...r=562044038463 so to keep the isolation from the motor control board.

I think the RMHV is essentially the same as the DDCSV, and I don't think there is an option to use step/dir for spindle control. And I don't think the 0-10V is isolated. The only way you could get it to work with a non-isolated drive would be with a 0-10V to 0-10V isolator, but they aren't common or cheap (IIRC the last time I looked they were upwards of £150).
The easier option would of been to get an isolated Sprint drive, however experience has taught me the motors on these are far more likely to fail and cause the speed controller to fail, rather than the controller to fail.

**Chas Ixion** · 17-01-2019

Your right the RMHV and DDCSV are more or less the same.

I'll use a pot connected to the sprint board for speed control for now.

After a bit of digging on the internet and head scratching I *think* I've figured out why the speed control was set for 50v. I think that the 50v is the voltage from the tacho at max speed rather than the max output.

But worried about your comment regarding the motor failing taking out the speed controller, what tests can I do on the motor to establish if its good or not?

**m_c** · 17-01-2019

Originally Posted by Chas Ixion

Your right the RMHV and DDCSV are more or less the same.

I'll use a pot connected to the sprint board for speed control for now.

After a bit of digging on the internet and head scratching I *think* I've figured out why the speed control was set for 50v. I think that the 50v is the voltage from the tacho at max speed rather than the max output.

But worried about your comment regarding the motor failing taking out the speed controller, what tests can I do on the motor to establish if its good or not?

Have a read of the manual for setting the pots. Plus I think there may be posts over on the Denford forum somewhere where the Denford guys give a few pointers for setting the drive.

Generally carbon dust builds up, causing ground leakage, and/or shorting between windings. However the motors are not the easiest of things to dismantle to clean properly. I damaged the tacho trying to get mine apart, but then I was more interested to see what was in it, as it was already destined for the skip as I upgraded to a servo spindle.

**Clive S** · 17-01-2019

I think the RMHV is essentially the same as the DDCSV, and I don't think there is an option to use step/dir for spindle control. And I don't think the 0-10V is isolated. The only way you could get it to work with a non-isolated drive would be with a 0-10V to 0-10V isolator

Not sure what you mean here, would you mind elaborating please.. I used the pwm signal from my bob and the https://www.ebay.co.uk/itm/111654184682 to convert it to 0-10V isolated for the spindle driver board.

**m_c** · 17-01-2019

Originally Posted by Clive S

Not sure what you mean here, would you mind elaborating please.. I used the pwm signal from my bob and the https://www.ebay.co.uk/itm/111654184682 to convert it to 0-10V isolated for the spindle driver board.

Does that board isolate the PWM in from the 0-10V output?
I'm not sure if the 0-10V output from the DDCSV/RMHV will be compatible with that board. It would depend on if that board is simply relying on referencing the PWM voltage (should be fine), or measuring the actual PWM.

Actually, I've just checked the spec of a DDCSV, and it states the spindle output can be configured as a PWM, instead of analogue. I can't find any mention of whether it's isolated though.

The problem with SCR type drives, is the far more common non-isolated versions have the control wiring at near mains voltage, so your 0-10V source has to be isolated. Denford did use isolated drives in some machines, so yours may have an isolated drive, or your BOB PWM may be isolated. The only guaranteed way to check without knowing the exact board you've got, is to power the controller up, and then measure the voltage between the speed control terminals and ground (or neutral/0V).

**Clive S** · 18-01-2019

Does that board isolate the PWM in from the 0-10V output?

This morning I checked the voltage between 0-10V and earth about 200V and between PWM and earth 1.5V so it isolates the two.

Click image for larger version.

Name: Control box.jpg
Views: 2657
Size: 419.5 KB
ID: 25338

Click image for larger version.

Name: pwm_board.jpg
Views: 2640
Size: 207.1 KB
ID: 25339

**m_c** · 18-01-2019

Originally Posted by Clive S

This morning I checked the voltage between PWM and earth about 200V and between 0-10v and earth 1.5V so it isolates the two.

Good to know.
Although I assume you meant to have those two voltages the opposite way around? ;-)

**Clive S** · 18-01-2019

Good to know.
Although I assume you meant to have those two voltages the opposite way around? ;-)

Well spotted. I have edited mine would you mind editing to save confusion for others.

**Chas Ixion** · 23-01-2019

Just a quick update. Got a scope on the 0-10v spindle speed output from the RMHV and its analogue and not PWM.

The manual seems to suggest that it is possible to configure the unit to output PWM but I can not find anything in the manual to show me how.