Novamill control box fault, duff power supply??

[bpmsl]

Hi,
I've picked up an unwanted novamill control box for spares for my machine and it seems to me that the power supply is duff.

When you power it up nothing happens but if you flick the master power supply switch the intermittently off the resultent spike allows the control board to run up and sit at 5. The mill doesnt power and the door interlock doesnt disengage but moving the interlok relay switch lets the control board move to 8 so at least that seems to be OK for a spare.

Any thoughts on whenre the fault is, as I said it seems that its a power supply issue. If so where should I be looking to check for voltages with my multimeter to confirm and any ideas on where to source spares? It'd be good to have a running box to swap out if mine ever dies.

Any help appreciated.
Cheers
BPM

[Denford Admin]

Check the power in connector terminals as shown on top right here:
viewtopic.php?f=54&t=2126

You should have 24 DC (or can be AC) on 4&5 (logic) and 1&2 (drives)
if it's AC, then I'd say 24 to 28 VAC should be fine, otherwise they should be 24VDC

[bpmsl]

Thanks for the pointers admin, so OK is not a power problem then, power across 4 & 5 30v ac, and 1 & 2 30v ac when safety relay switch is made. Also now its had a bit of time it seems to only have an issue booting if you have it running then turn it off then turn it on again too quick befor the residual charge decays, wierd...

anyway having spent some time following wiring in the box i'm now following another line of investigation... see next new item.

thanks
bpm

[Denford Admin]

If you can change any tappings then try get that 30Vac down to less than that.
I seem to remember issues with the Baldor not booting up / shutting down if the AC input was too high.

[bpmsl]

The transformer just has the three tappings, 110v (as marked), 30v (marked 28), 30v (marked 28).

As you mentioned it above can I use a separate 24v DC supply to the card and if so do I need to worry about polarity across the pairs of pins 4&5 (logic) and 1&2 (drives)? I assume they both have to be the same polarity?

Do I need separate supplies to each pair as the current transformer has separate tappings altho i dont know if they both route to the same winding.

What current rating should the DC transformenr have if appropriate?

Can I take a tapping from the 24v DC transformer that's already in the machine?

Any thought appreciated.

Cheers
BPM

[Denford Admin]

What we do on retrofits is put 24VDC to the logic supply and leave the 28/30VAC as is on the drives input.
We fit a 2amp 24VDC supply, but that's because it may be rewired to be controlling relays and solenoids as well.

[Martin]

I often rewire the logic to the 24 volts DC power supply. I think it overvolts if the ac is above 29 volts.I

[bpmsl]

OK thanks I'll do that on both as my origonal box still has the logic on AC and its reading 29.3v. Prha[ps that was why it was hanging at 5 on startup... and not the safety relay.

Help much appreciated.

Cheers
Barry M

[bpmsl]

Finally got back to this, the 24v DC mod worked a treat and now the unit powers up perfectly.

Thanks
Barry M

[Denford Admin]

Glad it worked out...I've added to this post to show how it's now connected:
viewtopic.php?f=54&t=2126

Can you confirm that 0v is on pin 5 and +24 on 4, or does it work either way round ?

[bpmsl]

Will check which way I've connected it up next time I'm in the workshop.

However from memory I actually connected the 24v via the AC transformer end of the loom so as to include the breaker / fuse in the card logic supply loop. I also made sure the +24v line went via the breaker. Not sure which pin that feeds the +24v to.

In theory I guess if it'll run on AC or DC there will be a rectifier in there and hence it'll accept any polarity, but that's just a guess.

Also whilst it powers up I haven't had the control box running with my mill yet because of potential differences in the machine connector wiring due to speed n feed pots / ATC wiring or design standard differences between 1999 and 2001. See my other current thread. (also this control box part number is hand marked up so it may have been altered ex works...).

Will keep you up to date.
Cheers
BPM

[bpmsl]

Pic of link cable attached, I connected 0vDc (core 60 at DC transformer) to the wire that was connected to the 0v output tapping from the transformer (Core 28 straight to card pin 5) and similar for the 28v AC and +24v DC (Core 61 at DC transformer) wires hence that feeds +24v DC thru core 27 via the breaker / fuse and onto core 29 then to connection 4 on the control card as per your diagram.

Still have to test it to ensure it works but it all powers up cleanly now.

And yes that is 14A mains lighting cable and a chocolate drop, it was all I had to hand rated over 10A as per the breaker / fuse.

Thanks for the help again, much appreciated.


Cheers
Barry M

[Martin]

Yes thats fine.

You could also have just moved the 2 wires coming from the transformer to the terminals on the din rail just above it. Terminals 60 & 61.

[Denford Admin]

And yes that is 14A mains lighting cable and a chocolate drop, it was all I had to hand rated over 10A as per the breaker / fuse.

Just be aware that the 24V power supply there is only rated around 1 Amp so it's really only fit for powering the control logic and a couple of relays - it won't power stuff like a machine light or solenoids (in case you were thinking of adding any)

[bpmsl]

Thanks folks.
Both points noted.

Cheers
BPM