Mini Mill Woes

[RayW]

My Clarke CMD10 (same as a Sieg X1) mini mill decided to die the other day. Assuming it was the motor that had died (2nd one), I shelled out £115 for a new one, only to discover that the fault appears to be with the speed controller PCB and that the old motor appears to be OK after all. Unfortunately, Arceurotrade from whom I bought the motor, does not accept returns of electrical items.
The fault is as follows. When you switch on the forward/reverse switch, you get a normal green power light on the control panel, but as soon as you switch on the speed controller switch (potentiometer) you get an amber fault light.
According to Arceurotrades's website, the circuit board for my machine is now discontinued. They list a later one, but will not give any advice as to whether it is compatible with my machine.
The motor is 230volt DC. In case the fault lies with the potentiometer itself, I have ordered a new one just to try it and see.
Has anyone had a similar experience with one of these mills and replaced the circuit board with the later version? The current one is type FC150BJ and the new one is XMT2315.
If I cannot get one, I will probably end up buying another identical mill so that I can transfer the various adaptions that I have made (longer table, belt drive conversion, separate control box) from the old one to the new one.
Alternatively, does anyone know of anybody in the UK who might be able to test and repair my current board?

[Firebird]

Hi Ray

Send a PM to my mate Barneydog, he may be able to offer some advise

Cheers

Rich

[tghs]

most of these mini mills use cheap spade connectors between the power cord and mill,, if you have not done this already remove them and replace with a more robust connectors..

[RayW]

Thanks Rich. Will contact Barneydog to see if he can help.

Thanks for the suggestion tghs. The connection from the power cord to the mill is fine as there is power to the control panel.

[tghs]

mine showed the same symptoms, according to Little Machine Shop its one of "do this first"

[Allen Smithee]

most of these mini mills use cheap spade connectors between the power cord and mill,, if you have not done this already remove them and replace with a more robust connectors..

There isn't actually anything especially wrong with spade connectors provided they are used within their specified current range and are fitted using the correct crimp tool and the correct size wire. In any application where there is vibration I would rate a correctly crimped and specified spade connector as a better solution than pretty well any soldered connector, and it's not like you'd expect to see Mil-std-38999 or Pattern 605 connectors in a machine tool.

AS

[Alyn Foundry]

Here's a photo of Ray's motor control circuit board.

[RayW]

Thanks for posting that Graham.The two bottom connections on the connector block on the right are marked "220 volt DC out". With the mains power on, and the green light showing in the control panel, I have tried touching the two motor wires on those terminals but there is nothing, so it appears there is no DC output. I have also now checked with a volt meter but zero reading.

I will try the new potentiometer when it arrives, but failing that, there appears to be a company in Luxembourg that may still stock the correct control board for about 85 Euros.

[RayW]

On studying the Arceurotrade photo again, I can see that my board differs slightly, but has the same part number, FC150BJ. The only possible defect I can see with mine is that the middle of the three small orange components at the top of the board may have overheated as the orange part should have a cross head slot like the other two, but looks as if it has melted. I have no idea what these are or if they are replaceable.
The attached photo shows my board. Usefully, all the cables that connect the circuit board to the control panel components are numbered to correspond with which terminal on the connector block they go to, so installing a new board would be quite straightforward.

[jadge]

............the middle of the three small orange components at the top of the board may have overheated as the orange part should have a cross head slot like the other two, but looks as if it has melted. I have no idea what these are or if they are replaceable.

Good grief, must have got hot to do that. The orange components are single turn preset potentiometers, probably surface mount. Do they have three legs? Should be possible to find a replacement. Of course one needs to know the value, which could be printed on the side. Even if a direct physical replacement can't be found another one can be wired in. In the UK I'd look at Farnell/CPC/RS for replacements.

Andrew

[Admiral_dk]

I frankly can't decide from the photo if the Trimmer (Pro speak) is melted or as it appears to me - has a dot of glue on top to prevent it being adjusted again - This is not an uncommon way of preventing unauthorised personnel from "fixing stuff / Improving it" ....

Looking at the one slightly closer to the lens - you see between 2 and 4 characters - 1-3 digits followed by either the letter R, K or M (the later not quite likely here) - I'm not sure they are SMD, but they might be.

Another way of writing the value is like the two blue Multiturn Trimmers to the right of the Singleturn ones :
503 => 50 * 10^3 = 50000 or 50K - Ohm is implied, without writing it.

[Don1966]

You can check the speed pot across the two outer terminals it should have 5 or 10vdc across it . This is your reference voltage used to control the board if it’s not there the board won’t work. If the small trim pot is burnt which I can’t see from your photo it could be a minimum or max speed adjust. This burnt pot could be caused by a shorted wire going to your speed pot if this is the case. If you have reference voltage and the board doesn’t work it needs replacement. Hope this helps....

Don

[Jasonb]

Common advice on ME is to put a household light bulb in place of the motor and if that changes brightness as the speed is adjusted then board OK.

[Zephyrin]

I have replaced simply the died rectifier bridge on my Sieg X2, as no signal was detected at its output, with a new one and added a small alum. plate bolted on as it had a hole in the middle, and it works faultless since about 14 years now.

[mikemill]

Ray

Have a look at this one https://www.ebay.co.uk/itm/Input-AC-220V-Output-DC-0-220V-Speed-PWM-Regulator-Controller-Motor-HHD6-G-1200W/372638753963?_trkparms=ispr%3D1&hash=item56c30024ab:g:AJwAAOSw

There are lot of others on ebay

Mike

[RayW]

Thanks all for your replies and suggestions. I must admit that I am completely out of my depth where electronics are concerned.

Andrew and Admiral-dk - I am happy that the little orange component has not melted as I initially thought. I think Admiral is correct and that the middle one has been sealed to avoid adjustment as there is clear printing on all three components.

Don - Can you explain more how to test the speed pot please. I have checked the voltage by connecting my voltmeter to the live input on the on/off switch and the negative to the input side of the pot and I get a reading of 240 volts. With the pot in the off position, if I connect the negative to the output side I also get 240v. If I then switch the pot on, the voltage on the output side drops to 74 regardless of the position of the pot.

Jason - I have heard that trick too, but as there is zero reading at the connections for the motor, that wouldn't work.

Zephyrin - Do you have any photos of the modification to your X2 please?

Mike - That looks good but the wiring up might be beyond me

[Don1966]

Ray you have a red, yellow and white wire on the pot. This is your reference voltage put you meter on the red and yellow wires the two outer wires it should have 5 or 10vdc on it depending on the manufacture. Make sure to turn the unit on with the pot switch.... if you have the voltage check again the voltage on the white and yellow when varying the pot. The voltage should vary as you turn the pot. Like Jason suggested a lamp across the motor output terminals can help to see if your producing an output. Just make sure the lamp is 240 v rating.

Don

[Barneydog]

Hi Ray,
Since you have ordered one fit tge new speed control but I doubt it is that.
The pots are factory set for max and min speeds, torque cut out etc. My board packed up some years ago as tgey are VERY prone to do. I swapped mine for a simple dc speed controler off ebay for about a tenner and works fine just has no torquw cut out but who really needs it....just listen to the motor. The boards are the same rubbish as tge lathes. My C3 lathe has a torque problem ie it cuts out too early. For example it kept cutting out today drilling stainless 303 with a 3.2mm drillbit. I will either swap for cheap dc controler or try to adjust the torque pot. Problem is finding which to adjust. I think little machine have all the board specs on their site.
Not worth buying board just use cheap 200v bc controler from ebay.

Jules

[RayW]

Thanks Don and Jules. Tried taking a reading across the terminals you suggested Don, but got zero reading. Do I assume that this means the pot is faulty? I will solder the new one in when it arrives and see if that cures the problem. If not, I am tempted to go with your suggestion Jules and fit a simple speed controller. If possible I would like to find one with forward and reverse although the times when i have wanted to run the mill in reverse have been very few and far between. As for torque cut out, my mill has been converted to belt drive so the belt will usually just slip if the cutter is overloaded.

[jadge]

To state  the obvious if you use a bulb as a load it needs to be an incandescent bulb. Is the motor brushed DC? In which case the output of the board will be a PWM signal rather than a DC voltage.

Andrew

[Jasonb]

yes they ar ebrushed DC.

I think that is why the light bulb is suggested as a basic tester won't show anything due to the PWM

[jadge]

Assuming that the PWM frequency is high then a digital meter will act as an integrator and will give a reading, albeit not necessarily accurate. An old school analogue meter would be better. The advantage of bulb is that it puts a reasonable load on the output as well as glowing more or less brightly.

Andrew

[RayW]

I tried a bulb across the terminals where the motor connects, but nothing.

[Don1966]

Ray if you don’t get an output across the pot the unit won’t work no matter if you change the pot. It is defected and needs replacing. Without the reference from the pot nothing will work.


Don

[jadge]

It is defected and needs replacing.

Agreed. The regular failure of these types of board just go to confirm the saying that any idiot can design a power circuit that will work. But it takes expertise, and costs money, to create a design that works reliably and will survive the external faults that can occur.

Andrew

[Allen Smithee]

I think that is why the light bulb is suggested as a basic tester won't show anything due to the PWM

It certainly should - incandescent lightbulbs will work with AC, DC, Chopped DC or indeed anything that develops an RMS voltage. They just heat up due to the current passing through a resistance, and they don't care which way that current is flowing. Dimmer switches are like PWM - they chop the current into short bursts - the only difference is that they chop AC rather than DC, so we consider them to have chopping angles rather than chopping periods.

PDR

[jadge]

Missing comma causes confusion!

Andrew

[Barneydog]

Ray,
Dont spend too much more money just buy cheap controler from ebay. I have had no use for reverse so just got forward variable. Make sure you buy one with higher wattage than you need...500?

JULES

[awake]

I would venture to guess that on any controller, forward and reverse are controlled simply by swapping the positive and negative poles of the DC output. All you need is a DPDT switch rated for the voltage & current.

[RayW]

Thanks for all the advice  guys. I have now ordered a Chinese speed controller box and awaiting its arrival. I did receive a new speed controller pot from Arceurotrade so will wire that in to the old board just to see if that was the problem.
I also eventually got a quote from Clarkes for a replacement controller board - £170!!
Considering I have already paid out £115 unnecessarily for a new motor and that I only paid about £250 when I bought the mill secondhand, I think less than £20 for the Chinese unit is a no brainer.

[RayW]

Wired up the new potentiometer today, but still nothing, so the board is obviously dead as suspected.
The Chinese speed controller unit arrived yesterday and was a very straightforward replacement for the old unit. As you will see from the photos, I have mounted it sideways to fit in the housing box. It has an on/off switch and a speed controller knob. Strangely, the green light comes on as soon as power is switched on at the wall, rather than operating with the on/off switch.

[Alyn Foundry]

Hi Ray.

Well....

Does it work??   

[RayW]

Very nicely thanks, so no excuse for not getting on with things now. The Sphinx is now temporarily sitting on a nice new trolley and I am in the process of sorting out exhaust, water tank, ignition system and gas supply. I am waiting until it's all done before posting any photos here or on the Alyn Foundry Facebook page.

[Don1966]

Glad to see you have it sorted out Ray. Happy chip making........



 
Don

[Hrcoleman]

That's a really neat fix.

I have the same Mill (currently in the market for an upgrade).  My Switch Potentiometer actually failed when the rotor stem broke inside the main body.  I went down to the local Jacar Electronics store to see if they had a spare on the shelf.  Unfortunately, they only had plain Pots, so I bought a secondary switch to add to the mix.  I know this isn't the same fault as you had.
I now have a new box screwed to the side of the mill body with the switch next to the Pot.

Cheers,

Hugh

Hugh

[mikemill]

Your tale of the electronics on Chinese made machines is just another example of poorly made boards. The mini lathe that is sold by many tool suppliers are also prone to their control boards failing.
I have a Syil X3 CNC mill that has failed many times simply because the wire crimps are made of foil rather than solid metal, thus they don’t hold the wire connection, thus you have to spend hours tracing the fault.
As the Chinese have taken over the machine tool market at hobby level and to some extent industrial there is not a lot to choose from.

Mike

[RayW]

As you may have read elsewhere, I managed to burn out the motor due to my own fault in overloading and massively overheating it. The new Chinese speed controller also seemed to fail in sympathy.
Fortunately, I already had a spare motor so just needed to buy another controller for about £20. All now working fine again.