Triac PC Has it died?

[plakey]

Hi everyone...

I recently bought a Triac PC (modified for USB and VR Milling CNC) from Ebay, my first ever CNC mill that I bought to learn a bit about. I have only had it a couple of days and it has seemingly broke. To be fair it is an old machine the guy selling it did say he noticed the spindle speed vary a little last time he used it but not much.

Tonight I have come to use it and I have very very slow spindle speed, putting VR Mill into Jog (no program) and starting the motor gives me no more than around 250 rpm at a guess, I crank up the spindle speed dial until show 4000 on screen and the motor barely increases to around 300 rpm maybe. I have put my test meter on the motor input terminals and varying the speed in VR mill from 250 to 4000 which produces a varying voltage at the motor between 17v and 20v DC.... I'm no expert at DC servo motors but that does not seem enough for what I believe is a 140v motor.

I have attached some photos of the controller hoping someone here can help me before my wife finds out I blew £2k on something broken

I'm safe with a test meter if someone can point me where to look

DSC02382.jpg (224.17 KiB) Viewed 12459 times

DSC02383.jpg (150.7 KiB) Viewed 12459 times

DSC02384.jpg (196.7 KiB) Viewed 12459 times

Cheers

Paul

[Denford Admin]

First off I'd go check the motor brushes

[plakey]

I tried to look at those last night, removed the cap, then removed a retaining ring but could not see how to get the brushes out.... is there a special tool or do I just grab the brass bit with a pair of tweezers or something and pull?

Do the voltage at the terminals seem correct?

Thanks

Paul

[Steve]

Visit the link below and download the Triac Diagrams.

They may not be identical to yours but the spindle works in exactly the same way.

download/file.php?id=701

The sheet you need to see is SD17.pdf, this shows the spindle drive.

Terminals 2 and 3 have an analog input of 0 - 10V DC 10v giving full speed, 5V half speed etc.


Pins 4 & 5 are the enable link (interlocking the spindle go relay and guard. This circuit must be OK for the spindle to run at all.

Pins 12 and 13 are the AC mains in and you should have 240V AC on these all the time.

Pins 8 and 9 are the motor output and you should see a DC Voltage up the the motor maximum on here (not sure what it will be but 140VDC sounds right)
The +ve terminal goes to the choke then the motor.

Check the Analog in first. try and start the spindle and run it to full speed. (you should have between 8 and 10VDC)

If you have this check the mains input then the DC motor out.

It is possible there is a bad connection from the electrical box to the machine check this as well!


Good Luck! Let me know how you get on

[plakey]

Thanks Guys!!... When I was looking for a machine I decided a while back it had to be a Denford simply because of the strength of this Forum and you haven't let me down.

I will be striaght onto this tonight and let you know results in the morning.

[plakey]

Well a little inconclusive I think.

Analogue input runs from 3v - 4.2v when I run the onscreen pot in VR milling from 250 -4000

Hardly any change in output DC voltage, runs between 18-20v when I move the onscreen pot from 250-4000

AC Input is 240v

There is something else I noticed with the analogue signal cables disconnected from the spindle drive I'm only seeing around 4v between terminals 1 & 2 or 1 & 3 I was expecting to see 10v there?

[Steve]

Hi,

You also have a feed over ride pot on the front of your machine (I think) is that up at 100%?

It sounds like the Spindle analog is the problem.

If you disconnect the blue and the red and measure the ends of the wires you should be able to measure the analog voltage.

It should change from 0 with the spindle off to a value between 1V and 10V as you change the speed demand.

The manual for the sprint drive is also a download.

download/file.php?id=950

Look at the typical applications page Section 6.1 If you can get a 10K potentiometer you could wire it to the drive pins 1,2 & 3 and they you should have full manual control of the spindle when the machine enables it.

If this works you can be sure the problem is the Analog.

The analog signal comes from the rack through the 50 way I/O distribution card. see sheet 5 of the machine drawings.

You can check the wiring of these back as far as the rack.

If the wiring is not the problem then it will be the rack controller card. This may meen you are better controlling the spindle speed by hardwiring the 10K pot direct to the drive and ignoring the internal control?

[plakey]

Thank you for your help so far, I will try the seperate pot test tonight as I don't have any kind of manual pot on the machine.

Are both of my suspect cards impossible to source/repair now?..... if you have any or know a repair shop I could make contact today and get prices.

Is the analogue control card the one next to the Baldor card connected by a large ribbon?....i.e 2nd from the left on the rack in my picture?

Oh just one other thing my Sprint card has a label saying it's a 1200, is it still the same manual?

Cheers

Paul

[Denford Admin]

Is the analogue control card the one next to the Baldor card connected by a large ribbon?....i.e 2nd from the left on the rack in my picture?

- Yes

And this picture should help:
viewtopic.php?f=15&t=634

[Steve]

Very quick check to try.

Remove the analog wires.

Put a wire link from 1-3 on the terminals (linking 10V to the analog)

Now try and run the spindle and it will go at full speed.

You can buy a 10 K pot at any electrical store (RS or Farnell Maplin etc for less than £2)

We can repair the baldor card. but will have to check which card has the analog circuit on it. could be the one with the 7 seg display.

Cost for repair £200 -£300

[plakey]

All this help is terrific on here..... Thanks

Just to let you know I spoke to Sprint, really helpful guy (Jim) suggested I check between 1 & 4 for 10v, there wasn't anything (about -.3v) so we have concluded the spindle drive is indeed faulty. I have ordered a replacement (nice to know they still make them!) for delivery tomorrow.....along with a 10k pot to get me going manually.

I'm still suspicious that my analogue is also faulty because with wires disconnected from the spindle drive there is nothing at all there regardles of where I set the pot in jog on the software. I know communication is all OK, all 3 axis work fine and I hear a relay click when I start the spindle.

Will let you know results as soon as I get the new spindle drive in place.

The card that is located next to the Baldor USB card does have an area marked out in the lower right next to the edge connector (not the ribbon end) that says analogue on it, no idea if that would be the drive analogue though?.


Thanks

Paul

[Steve]

Hi,

The analog circuit is on the card next to the one with the 7 seg display Linked by the ribbon.

Not sure if we can still get them repaired but we may have a spare removed from an upgrade.

Lets see where you end up with the spindle drive first as I am not sure on this rack version if the analog should be present offload.

Martin may know, I will ask him to reply.

[plakey]

Here is a picture of the card, it may help identification.

DSC02391.jpg (158.27 KiB) Viewed 12406 times

[plakey]

It's working again! but only with manual control

I fitted the new sprint board copying the dip switch and pot settings from the original and away it went.

After a satisfying myself it was all fine I decided to take off my 10k pot and try the analogue connection again.... as soon as I went to start the motor it took out the RCD in the house!.... which I have to say surprised me some what ...anyway I wasn't prepared to try that again so I went back to the pot and all is well.

I'm thinking that maybe the the analogue failed first and took out my sprint with it.

I would very much like to get it back as it should be so if you know where I can get a used/new/exchange or repair done I would be very grateful.

Many Thanks

Paul

[Steve]

Hi,

On the card photo you can see in the bottom right a section screened as Isolated Analog.

The spindle drive unit is not isolated. The Analog input floates at 240V. The control card should provide 0-10V that is isolated from earth.

It sounds like the card has failed which has resulted in the mains voltage shorting through this circuit and being connected to ground.

I would just try and trace the red and blue wires from the rack to the drive and check they are not trapped somewhere or shorting to ground. If it is a screened cable check the screen is not touching one of the cores.

Am currently working in the US but will check if we have any cards here.

There may be some people who have upgraded thier machines and have removed the old electronics with cards available.

Could be worth placing a post in the Clasifieds section. "Rack card required from upgraded triac"

[plakey]

Thanks I will wait to see if you guys have something if not I will try the classifieds and Ebay!

Cheers

Paul