Denford Triac Spindle Issue

[GingerNinja54]

Having had some issues with connectivity, I’ve had some success… yay!

I can now connect to and drive the axis from the laptop.
This includes by home and jog functions.
I can operate coolant pump etc, so machine and laptop are talking.

I’m struggling with the spindle though…
When activated, I can hear a solenoid/switch flick inside the control box, but nothing happens at the machine…

Any thoughts on where to start investigations??

Thank you

(Also posted on the Denford forum)

[John11668]

What sort of spindle drive / controller do you have

[GingerNinja54]

Sprint 1200

[John11668]

Do you mean this one . isolated inputs??

https://www.sprint-electric.com/product/1220i/

[GingerNinja54]

30490

This is an image of the drive…
Bearing in mind it’s 1995 machine… maybe today’s equivalent has the version you attached the link for?

https://www.sprint-electric.com/product/1200/

It may be that Sprint still support the old drives, if mine proves defective? Maybe worth asking the question.

[John11668]

I am sure sprint will be helpfull so worth asking them for info. Looks like you can download technical data on that link if you provide your details.

They are based in Arundel but last time I tried I had difficulty getting through but I did manage to get a number for their tech sales chap which I can maybe hunt out if you are stuck.

One thing that is apparent is that it is a non isolated board so your computer must be connected to it via an intervening board. Where do all those pale blue wires come from. Ideally post a pic.

[m_c]

What hasn't been mentioned, is the spindle drive fuse was blown (there's a concurrent thread over on the Denford forums).

I've just had a look at the wiring diagram, and the fuse should be 6.3A.

If the motor stutters/stalls briefly when running, it's could be either the SCRs on the drive are failing (they tend to fail short circuit under certain loads, which causes the stuttering/stalling), or the motor is either shorting out internally, or the brushes are not making good contact (which again gives the stuttering/stalling).

The issue with the spindle motor, is due to it having a tacho fitted, beyond removing the brushes, they are a nightmare to dismantle and clean.

I personally removed the DC motor and sprint drive from mine, and retrofitted it with a servo motor and drive.

[GingerNinja54]

Thanks for replies guys
(I’ve also got the thread running on the Denford forum… my thought was to cast the net wise to try and capture as much input as possible)

I had found fuse #F1 (spindle) to have blown…
I changed for a new 10A (as per wiring diagram I found for this year machine?)

Upon firing up the machine, the spindle ramps up to full revs and back down, to approx. 60-100revs, and stays there.
Once I reference the axis, I can stop and restart the spindle in manual mode, but can’t change the rpm??
I rebooted the machine and the same occurred…
I get 200mV across wires #54 & #55 at all revs.

Could defective brushes cause this?
Or more likely to be a drive issue or other?

@M_C… what was the cost of your drive and spindle, and where did you source this from?

[m_c]

I've not got much time just now to give too much of an in depth reply, but the revving up then settling down isn't normal.

As has been mentioned on the Denford forum, it could be a tacho fault.
The 60-100revs does sound correct for 200mV, given it's a 0-10V signal, so 200mV should give around 2% of max spindle speed.

If changing the jumper to ignore the tacho input doesn't work, I'd measure the voltage across the 54/55 wires when you power the machine up. IIRC the spindle drive shouldn't even be powered until the controller is fully booted, and the spindle go relay is activated.

I seem to remember there being some machine settings within VR Milling. Is there any relating to the spindle?
If the analogue output isn't working, then it somewhat restricts your options for controlling the spindle from the software.


I fitted a Kinco servo motor and drive at the time, which cost quite a bit. If I was doing it now, I'd look at Lichuan servos, but it involves making a complete new motor mount. I do have a thread on here about my Triac retrofit, and I think it includes some details for fitting the servo.

[John11668]

With the later drives I seem to remember mine running wild on tach feedback, but on my motor the tach wires had long been cut off . Maybe it just was not reliable ,
If you can select Avf feedback it should respond to the the analogue input.

[GingerNinja54]

Update:

With slider at TAC = spindle fires up to high revs and sometimes trips my supply RCD!
If it doesn't trip the RCD, I can usually (not every time) start/stop the spindle in VR5, but not alter rpm.
With slider at AVF = spindle fires up to lower revs (1k rpm?) then stops.
I am not able to start/stop the spindle in VR5.

Wires #54 & #55 removed from Sprint1200 = spindle does fire at all
Wires #54 & #55 linked out on #1 & #3 connector on Sprint1200 = same as with #54 & #55 in position (incl same with the TAC/AVF slider)

At startup, both TAC/AVF, I measure 11.5v across #54 & #55

The only spindle settings I can see in VR5 are max/min rpm, and check boxes for manual, speed pot & external speed pot...

Help!

[John11668]

I think you should contact sprint for advice .
I found they were a helpful bunch

[m_c]

It sounds like there is some kind of isolation issue with the drive speed control.

If the drive speed control is being connected to ground, then that can cause an RCD to trip.
The speed control circuit on these kind of drives sits around half of mains voltage, so if you connect it to 0V/GND (the control electronics will typically tie 0V to GND), then you've just created an earth leakage which an RCD will detect, but as it'll be pretty low current, it may not always be enough current to trip the RCD.

I wonder if the isolation on the controller has failed.
A manual fix, would be to install a potentiometer to control the spindle speed. There is a slim possibility that I may still have a suitable potentiometer kicking around the workshop, but I won't have any time to look until next week, as I'm working at an event all weekend.

[John11668]

It sounds like there is some kind of isolation issue with the drive speed control.


I wonder if the isolation on the controller has failed.
A manual fix, would be to install a potentiometer to control the spindle speed. There is a slim possibility that I may still have a suitable potentiometer kicking around the workshop, but I won't have any time to look until next week, as I'm working at an event all weekend.

From what I can see sprint 1200 is a non isolated drive .
I am told that a potentiometer should control speed even directly connected but it will be supplying an input at the mid point of 170v or so. if you want to send signals from the computer there has to be an intervening board .

[m_c]

From what I can see sprint 1200 is a non isolated drive .
I am told that a potentiometer should control speed even directly connected but it will be supplying an input at the mid point of 170v or so. if you want to send signals from the computer there has to be an intervening board .

There is an intervening board. The Baldor controller that Denford fit to their machines.
However I'm not sure if the Baldor controller does the isolation, if there is a separate isolated supply for the Baldor controller specifically for the speed control, or if the analogue speed control is done by a totally separate board.
There is also the added complication that this machine has been upgraded from it's original serial controller to a USB controller, so I don't know how much may have been changed from the wiring diagrams that are available on the Denford forums.

I know KB drives of that era often had an option for isolated inputs, but I don't think Sprint did.


GingerNinja, have you traced where the 54/55 wires go to? Do they connect to the controller, or do they connect to the drive rack?

[Chaz]

You can replace with the i1200 or i1220 Sprint Drive. I went this way as my board wasnt functioning on my previous Triac.

[John11668]

I would certainly recommend the 1220i model. It is simple to connect, but dont go for a new one until you have established that your existing one is faulty,
You need to see if it will respond to an external run switch and a potentiometer.

[GingerNinja54]

Ref 54 & 55…
They run from Sprint drive to the drive rack, above the USB board

30498

Spent a short amount of time, doing some more investigation…
When booting up mill and spindle ramps up, SGR is NOT energised.
With SGR removed, spindle still goes rogue and ramps up on its own!
Removed #54 & #55 from green bar at lower end…
With spindle stopped, 180mV across terminals.
176mV @ 1000rpm
182mV @ 2000rpm
185mV @ 3000rpm
185mV @ 4000rpm

Haven’t got a 10k pot yet for other tests, but will do so soon.

There is an intervening Baldor board.
I’m waiting for Sprint to come back with some more info/prices…
I happy to go with either the 1200 or 1220i… they aren’t ‘megabucks’, but if it’s the Baldor board, it could still be a waste of cash… so still trying to prove what’s what.

[Chaz]

You have to get the i version otherwise you will blow devices. Ask me how I know this ...

[GingerNinja54]

You have to get the i version otherwise you will blow devices. Ask me how I know this ...

The original drive Denford fitted is non-isolated from the factory, so whilst the 1220i may be an upgrade, the 1200 should work fine… shouldn’t it?

‘How do you know you need the i version?’

[Chaz]

The original drive Denford fitted is non-isolated from the factory, so whilst the 1220i may be an upgrade, the 1200 should work fine… shouldn’t it?

‘How do you know you need the i version?’

Mine needed the Isolated version else it would damage the CS Labs controller. So I suppose it depends on what the source of your 0-10 V is. Not read the full thread.

[GingerNinja54]

No worries. I appreciate the comments regardless.

Excuse my ignorance… the CS Labs Controller… is that instead of the Baldor board for communication etc?

[m_c]

The fact the drive runs with the SGR (Spindle Go Relay) relay removed, indicates either a fault with the sprint drive, or somebody has altered wiring.

I think I'd start with comparing the wiring to the wiring diagrams.

54 should go to terminal 49 on the connector board, and 55 to 47.
The enable circuit passes through the SGR, and the enclosure safety switch relay -
30499
If the spindle still activates with the 51/53 wires disconnected from the drive, then there is an issue with the drive.

But that wouldn't explain why you're not getting the expected 0-10V output.
You are measuring the voltage between the 54/55 wires, and not to gnd?

[GingerNinja54]

Everything I’ve checked has been in line with electrical diagrams… not checked everything, but everything I have has been correct.
The 54/55 were correctly in 49/47.
Spindle activates with 51/53 removed.
Yep, measured across the board terminals and at the wires (in case I was being stupid!).
Not tested against ground.

Disconnected 54 & 55 from Sprint and fitted a 10k linear potentiometer;
Spindle fires up as machine boots up (incl. with SGR removed).
@10k, spindle was running at approx 1k rpm (by eye/estimated)
@9k & less, spindle increases in rpm rapidly
I.e. NOT 10k = 250rpm / 5k = 2000rpm / 0k = 4000rpm
More like, 10k = 1000rpm / 9k = 2500rpm / 8k = 4000rpm

Increasingly looking like both the Sprint drive and Baldor board are both dead..?
Sprint boards seem readily available, but anyone know of any Baldor boards? (Doubtful I know…)
Other options…?

[m_c]

I did finally look for the pot tonight, but I couldn't find it. I know where it was prior to me re-arranging the workshop to get my new lathe in, but I have no idea where it is now :/


The sprint drive certainly shouldn't power the spindle without any input.
The speed control also indicates a problem, but I'm wondering if somebody has added in the 0-20mA link, as that could give strange results if you then try to control speed by a pot.

It may not be the Baldor controller itself that is the problem.
Although this post isn't applicable to Triacs that use a full rack, it shows that the analogue output is done on a separate output board - https://www.denfordata.com/bb/viewtopic.php?f=54&t=325
I'm guessing on the full rack system, this will be done on the custom card next to the Baldor Nextmove ST card.
It's probably worth pulling out the custom card, and checking for any obvious issues.

[GingerNinja54]

No problem. Thanks for looking.
(I ordered one from Amazon at 21:30… it arrived at 11:30 the next day! Bearing in mind I’m in Cornwall… that’s pretty amazing!!)

Thanks for additional thoughts…
I couldn’t see any components that were fried or anything on the custom board, fuses are ok etc… anything else I can check?

(Will post a pic… if I can work out how!!)

[m_c]

Next step is electronics knowledge, and tracing the relevant circuits.

The big problem however, is testing the cards under power, as being rack mount, it won't be easy to probe components when installed.

I think I'd start by removing the rack, and tracing the analogue wiring, to find out where the analogue isolation circuit is. From there it would be a case of starting with the basics, like checking the DC/DC converter is getting power, and is working.
The DCDC converter might actually be pretty obvious, and there is possibly only one of them.

It's probably worth posting a photo of the custom card, and we can point you in the right direction of where various bits are likely to be.

[GingerNinja54]

30500

Here’s the custom card… any pointers gratefully received!

I’ve been onto Sprint and they were really helpful.
Info on assessing and potentially repairing the existing drive, as well as quotes for new.
I’ll study the wiring diagrams and go from there, with regard to tracing and locating a converter.

[m_c]

That card is just logic chips and opto-isolators.

What's on the card to the left from that one?

[GingerNinja54]

30501

This is the first card, to the left of the custom card.
This is the Baldor card.

The cards to the right of the custom card are the 3 individual axis cards.

[GingerNinja54]

The full cabinet…
30502

[m_c]

It's the card inbetween (second from the left) we could do with a photo off.

[GingerNinja54]

Oops! Sorry… attached wrong image!

I’ll try again… :)

30503

[GingerNinja54]

30505

…the whole cabinet and rack.

[m_c]

That's handy, they've even marked out what area of the board does :)

First thing I'd be checking, is if the NME0512D (5 to 12V DCDC converter) is outputting 12V.
If it's not, then I'd be checking to see if it's receiving 5VDC.

Beyond that, you really need an oscilloscope to check things.
It's a case of seeing if the opto-isolator is receiving a signal (from that previous thread, the Baldor outputs a PWM signal, which is amplified to drive the opto-isolator), and if the opto-isolator is switching it's output. It's a case of working through the circuitry to see where you are, and are not getting the required signals.

Off course, the problem is doing all that while the card is installed in the rack.
I'd probably solder on jumper wires to test the key points (8 wires - both sides of DCDC converter, and opto) to establish at least what side of the isolation is at fault.

[GingerNinja54]

Hi all - thanks for the help & support in identifying the issue with the spindle drive 👍🏻

I sent the drive to Sprint, who were super-helpful by the way, for investigation prior to repair or replacement.
It proved not cost effective to repair and the 1600i was recommended as the replacement.
A couple of hours making up a new mount (as it’s bigger than the 1200) and wiring in and we were in business!
No ‘rogue behaviour’ from the spindle on boot up and no tripping the power!

I’m still apprehensive about wiring into the mint board, in case that’s what killed the old 1200.
So I’ve wired in a 10k pot across #1 & #3 on the board.
This controls the spindle rpm, but I’ve still got an issue in that I don’t get full range.. by ‘educated guess’ (uncalibrated 😉) I reckon I’ve got 3krpm - 4krpm… but no lower.
I’ve played with the minimum and maximum rpm’s, but still stuck at the minute.
I’ll get in touch with Sprint, but anyone retrofitted a 1600 or 1600i spindle drive?

Thanks

[m_c]

What is the rated speed of the motor?
I seem to think the original motors were rated at 3000RPM.

As long as the sprint drive is outputting the rated motor voltage, then everything is doing what it should be, as with DC motors, Speed is directly proportional to Voltage.

[GingerNinja54]

30577

4000rpm

The bit I don’t get is that the pot is working, but not giving me the range it should.
I guess if I check the voltage output from the board / input at the motor I’ll get an idea if everything is as it should be.

[m_c]

Checking the voltage will give a definitive answer, but I've just realised you said you only wired the pot across 1 and 3. It should be wired to 1, 2 and 3.

[GingerNinja54]

Thanks… had this realisation too, and guess what?
Being wired correctly makes it work correctly… who’d have thought it?! ��

Now to sort the comms properly… new post coming shortly…