Denford Software & Machines

Hello,

I recently got both a Novamill and Novaturn for the Edinburgh Hacklab. It is a open-community project trying to encourage people to be makers

However I have a problem.

The Novamill has a peculiar failure; after a short time the Novamill would lose contact with the host computer. This could happen if the machine is left connected to the PC but not moving for a long time and if running a programme it happens a lot sooner - sometimes within seconds.

As a bit of fault finding I swapped the Baldor F391 cards from the Novamill to the Novaturn. Subsequently the Novamill is fine and the Novaturn now has the problem. I've diagnosed the Baldor card is to be faulty

Using a thermal camera on the sick Baldor card I identified the polyfuse near the bridge rectifiers was running hot. I swapped it with another which is now thankfully running cool. However, the problem still exists.

As an experiment I watched the LED display on the controlboard during a very short trial machining run. When the controller drops communication with the PC, the LED display is still visible but is significantly dimmer (about 1/3 brightness of normal). The PC cannot establish communication with the controller anymore.

I then turn the controller on then off a few times and controller springs back to life and the PC syncs, sometimes needing to download the MINT file.

Has anybody got any ideas? I'm really stumped...

Thank you

Hi,

The problem is probably the regulator on the vertical end plate heat sink. The regulator has a thermal shutdown which would drop the 5V logic.

I would check the thermal paste behind the regulator and also check the screw is holding it securely to the heat sink.

You could try a fan to prove if this is the cause.

Hi, thank you for getting back to me.

I did have a suspicions that it was the regulator. There does appear to be plenty thermal paste and I can check the screw.

What is the number of the regulator in case I need to replace it?

Thank you again

The regulator is shown in the bottom right hand corner of the photo below.

That is the one - do you know the make and model of the chip and where I can maybe order one?

Thank you,
Scott

Not sure of the part but I think it supplies 12v and 5V

Is the chip not identified normally the part number is printed on them.

I am working away for a couple of weeks so will not be able to take a look at one for a while

Hi Steve,

Thank you, I think the part number will be on the chip. I was just asking in case you knew of the top of your head so I could order one.

I'll pop in to the Hacklab and find out.

What sort of temperature will make the regulator fail?

Thank you again,
Scott