Novaturn Spindle not running

Garvock · Post by **Garvock** » Thu 03 Jul , 2008 22:05 pm

Hi guys,
I have recently purchased a Novaturn with air operated guard - chuck and ATC. I have it all set up and working OK apart from the spindle. It rotates freely by hand, the belts are OK but the motor is not spinning up. It seems to want to go as it intermittently turns erratically, i.e. it does not rotate steadily but gives a half turn or so and stops, other times nothing at all happens. Before I start taking things apart does anyone have any ideas. I did think that it may be sticky brushes but access is a bit limited for the back brushes, what is the recommended way to access the motor?
Thanks in anticipation.

Keith

Martin · Post by **Martin** » Fri 04 Jul , 2008 6:53 am

It may be worth checking the inputs & outputs on the spindle drive first. If the brushess are worn then you will still see the correct DC output from the spindle drive.

The drive is normally in the bottom right hand corner of the electrical box.

Pins 2 & 3 are the analogue voltage. (0 to 10 volts DC depending on speed requested.)

pins 4 & 5 are the run contacts. (From what you are saying these should be OK)

pins 8 & 9 are the spindle motor connections. (This is a DC output depending on requested speed. Guessing around 160 volts DC at top speed)

Pins 12 & 13 are the 240 volts AC input.

If you see the correct output to the motor then it must me the wiring/brushes/motor but it may be a analogue fault.

bradders · Post by **bradders** » Fri 04 Jul , 2008 9:11 am

This may be of help ?

Problem :- Spindle will not run

Symbols :- SGR - Spindle Go Relay
:- GIR - Guard Interlock Relay

Symptoms :- 240V AC to Machine OK
All fuses, including those on Spindle drive and control board OK
Power LED illuminated on Sprint 1200 spindle drive board :- 24V DC present
Stall LED illuminated on Sprint 1200 spindle drive board :- Motor has stalled

Terminal designations

Terminals on the bottom of the Sprint 1200 spindle drive board (Left to right)

Terminal No Wire No Wire colour Voltage Function

1 Not connected - - -
2 2 Blue Ov DC Analogue speed control from Drive board
3 3 Red Ov - 10v DC Analogue speed control from Drive board
4 84 Blue Link Run link thro SGR contact for Spindle Drive board
5 85 Blue Link Run link thro SGR contact for Spindle Drive board
6 Not connected - - -
7 Not connected - - -
8 20 (17 N/Mill) Black Ov DC 0V DC to Spindle Motor
9 21 Blue 125v DC Around 160V DC on full speed to Spindle motor (Microturn)
10 Not connected - - -
11 Not connected - - -
12 N Black Neutral AC AC supply Voltage
13 L Black Live AC AC supply Voltage (Usually 230 V AC)

Terminals on the top of the Sprint 1200 spindle drive board (Left to right)

1 87 Black Ov DC Solenoid on GIR
2 Not connected - - -
3 88 Black 24v DC Solenoid on GIR

Solution

During testing the STALL LED illuminated, by disconnecting wires 20 and 21 to the spindle motor the Spindle drive
board booted up correctly, suggesting the spindle drive board was working correctly.

With wires 20 and 21 still disconnected the spindle motor was checked for continuity / Resistance and proved
satisfactory i.e. Not OC (Open Circuit)

The Chuck (i.e. spindle Motor) was rotated by hand and few revolutions and a re boot of the VRTurning software instigated.
The STALL LED did not illuminate and the spindle ran albiet a little erratically at the start but after a few minutes
seemed to settle down to run smoothly

Conclusion

It would suggest that with the spindle motor not running for a while, that there could have been some
contamination/corrosion between the carbon brushes and the spindle motor Commutator (The commutator needs to be a bright
brass colour, note? if the commutator has carbon deposits on it then the carbon brushes may be worn and will need replacing)

Garvock · Post by **Garvock** » Fri 04 Jul , 2008 13:02 pm

Thanks for all that info, I have checked out your suggestions and all seems OK. When I remove the fork from the door and put in the guardmaster(not recommended I know) if I give the chuck a quick spin by hand the solenoid in the guardmaster clicks in and out.
Any suggestions greatly appreciated!

Keith

Post by **Denford Admin** » Fri 04 Jul , 2008 15:49 pm

I give the chuck a quick spin by hand the solenoid in the guardmaster clicks in and out.

Here, you are just proving that the motor tacho or spindle encoder feedback is working.
I don't know how any of this is wired but would guess:
The drive may have a NOT Zero Speed output, which is connected to the door solenoid, which would mean the motor tacho is being read ok by the drive
Or
The control electronics or logic is reading the spindle encoder ok, and energising an output to lock the guard solenoid when it "sees" the encoder spinning.

I think you really need to have a good look at the motor and tacho brushes and comms - both these will wear, so are the first thing to check out.

Martin · Post by **Martin** » Fri 04 Jul , 2008 15:57 pm

What reading do you get on pins 8 & 9 ??????????????

Garvock · Post by **Garvock** » Fri 04 Jul , 2008 19:32 pm

Hi
Have had a good check over the control box. It looks like the problem is with the spindle drive. Have access to another Novaturn so swapped the boxes over, did not have full control as machines configured differently but the spindle spins up OK. replaced original box and checked voltages as suggested. zero volts from pins 2-3, 4-5, 8-9. 240 in OK and board lights up OK(no stall). All fuses checked, relays XDR,ZDR,SGR and GSIR are indicating after M3 command given. Please don't tell me I need a new spindle drive!!
Thanks again!
Keith

Martin · Post by **Martin** » Sat 05 Jul , 2008 0:07 am

From what you are saying it looks like the analogue voltage going in to pins 2 & 3 has failed. Did you check while requesting the spindle to run at top speed with the speed overide pot turned up to 100%.

You can check the drive by fitting a potentiometer accross pins 1,2,3 on the spindle drive board.

Denfords can offer a service exchange repair for the control board if you want.

Garvock · Post by **Garvock** » Sat 05 Jul , 2008 13:36 pm

Hi
Thanks for that info. What would a service exchange cost?

Keith

Garvock · Post by **Garvock** » Sat 05 Jul , 2008 15:26 pm

Hi
Just an update, when the spindle does turn I am getting 0.2V pins 2&3 and 2V pins 8&9.

Keith

Martin · Post by **Martin** » Sat 05 Jul , 2008 23:11 pm

Sounds like the control card has failed. Should be around 10 volts dc on 2 & 3 when top speed is requested.

Garvock · Post by **Garvock** » Sun 06 Jul , 2008 20:49 pm

Hi
Have now swapped the spindle drive for a known good one, no difference. Put the spindle drive from the faulty machine in another lathe, worked fine no problems so drive is OK.
Back to the faulty machine,there was no output from the Control board pins 1&2 so as suggested looks like faulty control board. As a last resort I tried a hair drier on the card, I have tried this many years ago on a PCB and it worked. Bingo, after about 30 seconds the machine burst into life. I am getting 9V from the controller and 135V output from the spindle drive, checked speed with tacho 3500rpm so all OK until it cools down, after about 10 minutes it slows and stops again. If I repeat the hair drier all is OK again.
This works when I heat round about the serial port on the Denstep Controller, there is a battery next to the port, what symptoms would I get if this was faulty? The battery is marked Varta 1299 2.4V 110 mAh Ni-MH, this does not seem to be a current battery, do you know a replacement?
Sorry to go on but hopefully I am getting close now!

Keith

Steve · Post by **Steve** » Mon 07 Jul , 2008 11:04 am

Hi,

I am sure you have a fault on the bottom card around the spindle analog circuit. We have see this in the past. The spindle analog is generated by a Pulse width Modulated signal generated by an Op amp.

If the op amp degrades the switching threshold drops and the output no longer switches. Heating the chip may resolve the issue short term.

Unfortunatley the components are surface mount nd are mounted on the bottom card of the PCB below the RS232 connector.

If you remove the top card you can see a potentiometer for fine adjustment of the analog and the OP amp and resistors are in that area.

You may want to try and adjust the potentiometer it may make a difference (its a 10 turn type)

If this does not work you have only a couple of choices.

Repair the PCB. Where are you located? If in the USA you need to contact Denford Inc for an exchange price.

Hard wire a pot to the spindle drive so that whenever the spindle starts the speed is set by the pot.

Hard wire an analog voltage to the spindle drive so the spindle always runs at a fixed speed.

Hope this helps?

Garvock · Post by **Garvock** » Mon 07 Jul , 2008 12:52 pm

Hi Steve
Thanks for that, will try your suggestions. I am in the UK what are my options on an exchange PCB?

Keith

Garvock · Post by **Garvock** » Mon 07 Jul , 2008 16:00 pm

Hello again
I have tried adjusting the pot and I can get the spindle turning at a fixed speed from 0-max but only by adjusting this pot I have no software control apart from stop and start. The speed override has no effect either.
Any other ideas or should I just keep adjusting the pot a bit at a time?

Keith

Martin · Post by **Martin** » Mon 07 Jul , 2008 23:33 pm

Hi

I have always replaced the cards under the above fault condition.

The pot is normally used to set the lower speed & then max speed is set on the drive.

Steve · Post by **Steve** » Tue 08 Jul , 2008 10:50 am

Yes the card is the answer.

Contact Denford Service and ask for Martin.

He should be able to sort out the service cost of an exchange board. To get them repaired takes a bit of time.

I suggested adjusting the pot as i thought it may get you running.

Steve

Garvock · Post by **Garvock** » Fri 18 Jul , 2008 21:08 pm

Hi everyone,
Have now replaced the bottom board as suggested and machine now works 100%. Thanks to all for your help, much appreciated!!

Keith

Denford Software & Machines

Denford Software & Machines

Novaturn Spindle not running

Novaturn Spindle not running