speed control pcb for Clarke CL300 lathe

[Les Jones 1Participant @lesjones1]

Hi Savinay,
I have found this manual for the Clarke CL300M. Does the wiring on your lathe corespond to the diagram on page 30 of this manual and is the control board an XMT2325 as shown in this manual ? (Or is the board an FC250 as in the link that Neil posted ?

Neil, Thanks for posting the information about the forward/reverse switch altering the speed range. I had been trying to think what the connections from the forward/reverse switch to connections P4, P5, & P6 might do.

Les

[Savinay BhariParticipant @savinaybhari]

thanks again guys,

my board is the very old FC250J, i have uplaoded a pic, i dont thing any connections will be wrong as they i have not changed anything yet and lathe was working when the ebay guy demoed it to me.

how do i check R2 on the board? sorry i have no clue on electronics i am a automotive engineer by trade but mostly sit on desk all day doing paper work. i can handle mechanical things but no clue on electrics

 

Edited By Savinay Bhari on 23/03/2015 20:52:42

Edited By Savinay Bhari on 23/03/2015 20:53:16

Edited By Savinay Bhari on 23/03/2015 20:54:22

[Neil WyattModerator @neilwyatt]

Right, It's an FC250 – look at top left of the pic. Same as my old board.

Neil

[Les Jones 1Participant @lesjones1]

Hi Savinay,
With the lathe unplugged from the mains and with the forward/reverse switch in the middle (Off) position with a multimeter connected to terminals P1 and P4 on the board you should get a reading of about 20k ohms. I expect that with the switch in the reverse position you will get the same reading but with the switch in the forward position the reading will be almost zero ohms. (I may be wrong about which position of the switch gives zero ohms.) Confirm which position of the switch gives the zero ohm reading in your reply. If R2 is open circuit I would expect you to get a reading of about 230K ohms. If my understanding of the way the circuit works is correct I do not expect R2 to be the cause of the problem. When the switch was in the reverse position (The position that caused the motor to run as it should.) did the speed control controll the speed smoothly and was the maximum speed correct. (Assuming you have a tachometer.)

Les.

[Savinay BhariParticipant @savinaybhari]

yes between p1 and p4 the resistance is 21.2k Ohms in both middle and reverse and drops to zero when put into forward.

in terms of the running in reverse, i would say yes the transition from slow to fast was smooth, dont know if the speed is right as the motor is not connected to the lathe at the moment, since if i do connect it to the lathe the fuse goes eventually as the motor starts to arch so i dismounted it. so cannot be sure if its getting to the right speed and dont have a tachometer either.

one odd thing in forward postion is, when the motor speed control knob is bought to zero and it clicks off (going complety anticlockwise), if i twist the knob even further anti-clockwise the motor flutter a bit on and off it doesn’t run but will kick to life then off then on and so on, the same does not happen when switch in reverse.

In forward if the speed control knob is opened just a bit about 15-16 volts or so the motor can easily be noted to stop start stop start the stop are very defined. So definitely there is a voltage pulse coming on and off or AC voltage is being fead like. I can see the fluctuation on the volt meter too.

Something I cannot explain is, in forward or reverse while connecting a multimeter to the motor output wire the voltage is read a steady 60V for example, reverse the multimeter contacts/or swap motor output wire and the voltage fluctuates 10-60-10-60v…. etc…. This is both in forward and reverse. But only affects the motor in forward. I don’t know what this is I cannot explain, how does changing polarity make the voltage fluctuate on the meter being DC?

 

Edited By Savinay Bhari on 23/03/2015 22:37:01

Edited By Savinay Bhari on 23/03/2015 22:37:33

[Les Jones 1Participant @lesjones1]

Hi Savinay,
The resistance readings confirm that R2 is OK and that my understanding of how that part of the circuit works is correct.
The way the meter reading changes from a steady reading to a pulsing reading when the leadsare reversed is very strange. I would expect it to just change the sign of the reading. (+60V one way -60V the other.)
Prior to yor last post my understanding was that the motor worked correctly when the switch was in the reverse position but after your last post I think you are saying that when the motor is put under a slight load by refitting it to the lathe the arcing on the comutator returns and the fuse blows. Is this correct ?
Is the voltage rating of the lathe correct for your country ? (I assume that it will be as I do not think you travelled to a different country to buy the lathe.) What is the mains voltage in your country ? You do not even say which country you are from in your profile.
Are you sure that you bought the corrct version of the motor to suit the voltage in your country ? There are different versions of the board and motor for 110V and 230V mains.
I think you will have to find someone with a better understanding of electronics to help you. It is much easier to fault find when you are by the machine than to do so just by asking questions.

Les.

Edited By Les Jones 1 on 24/03/2015 09:15:11

[Savinay BhariParticipant @savinaybhari]

Thanks Les, I am from Basildon, Essex, UK and bought the lathe from Whitstable, Kent where the previous owner had it from new (bought from Machine Mart) so all setup is 230V, motor is also 230V as it has a clear sticker on it saying 230V.

In terms of the motor running on lathe or off lathe it will arch in forward and run smooth in reverse. The fuse will blow even out of the lathe if I increase the speed control knob to more than 1/3 the speed as arching gets violent, it’s just that now that I know it will blow the fuse, I don’t do it hence on very low turn of the knob you can clearly see it start-stop etc. If you load it up by mounting in the lathe the arching will increase which I guess is normal behaviour under load, again only in forward when in reverse there is no arching even mounted on the lathe.

I haven’t got anyone around who will have a clue on this type of electrics, I am not new to motors and speed controllers as I fly large model helicopters which use 50V DC brushless 6-8KW motor and 100-150Acontroller but everything in that hobby is sealed, is usually a simple case of replace it when things go wrong. I would have done the same here but this doesn’t appear to be an robust system plus hurts putting money in something which I have never used at all, Its rather off putting to put money on something which looks to me like even if I fix this, it is going to happen again from reading all the cases on the net. Hence trying to chase see if I can fix it and learn from it and just use the lathe to learn on. my plan was to learn on this and get a better one in the future, definitely will be get something running on AC and mechanical pullies those seems a lot more robust than 230v DC controller stuff.

I actually have a no need for lathe as yet, just that I always wanted one and when one came up nearby on eBay I though let me give it a go plus it came with a lots of tools, guess it not the right time to start my machine shop adventure. Ebay is always if it sounds too good to be true thingy, sad part is it was only 100 quid cheaper than a new one and hurts even more that if I fix it now its going to cost me more than new one.

Thank you all for the help once again, I guess it’s time to move on and take it as a lesson, if anyone want a cheap lathe which is mechanically sound please let me know, it looks barely used by the paint work but hai who know I have already been done. I did DTI the chuck it which has a 10 micron run out which I think is mechanically very good and sound.

Or I may follow this thread https://letsbuildone.wordpress.com/mini-lathe-motor-upgrade/

I have all the parts already as they all come model aircraft applications. Anyone tired this? Only things that puts me off this is by going 24V your amp draw increases massively and you need a massive power supply. I have one already got a monster 60A 24v supply but it makes the lathe less compact as PSU is almost ½ the size of the lathe

Edited By Savinay Bhari on 24/03/2015 12:59:10

Edited By Savinay Bhari on 24/03/2015 13:00:44

[John Stevenson 1Participant @johnstevenson1]

Posted by Savinay Bhari on 24/03/2015 12:58:22:

Or I may follow this thread **LINK**

I have all the parts already as they all come model aircraft applications. Anyone tired this? Only things that puts me off this is by going 24V your amp draw increases massively and you need a massive power supply. I have one already got a monster 60A 24v supply but it makes the lathe less compact as PSU is almost ½ the size of the lathe

.

I like the quote:-

"Now my first thought was “Are you taking the expletive?!” I could build one for a quarter of that… plus a solid weekend."

So a solid weekend in my book is 20 hours based on double time or even triple being weekend thats 40 to 60 hours. Now times hourly rate and lets just say it's cheaper to but a new Conquest lathe from Chester or Warco.

OK I'm working but everybodys time is worth something.

Perhaps I should get him to build me some and pay him double of his "quarter of that" ? That would still save me half.

[Neil WyattModerator @neilwyatt]

Savinay,

Remove the black caps on either side of the motor and remove the brushes.

Take the end cap off the motor and clean the commutator carefully with particular attention to any dust between the segments.

If the brushes look worn down compared to this

Then buy C3-150-MB Motor Brushes (Pair) from http://www.arceurotrade.co.uk/Catalogue/Machine-Spares/C3-Mini-Lathe-Spares

Neil

[Les Jones 1Participant @lesjones1]

Hi Neil,
the motor that Savinay is using is a "new one" (Although he does not say if it is new from a dealer or bought on ebay.) I think you pointed in the right direction when you mentioned that the switch also reduces the speed in reverse. I think the problem occures above a certain speed setting which is not reached when the switch is in the reverse position. I was wondering if it could be the 47 nF capacitor across the motor breaking down above a certain voltage. If this happend then the over current circuit would come into play and the motor would be working as a generator with the capacitor behaving as a temporary short circuit across the motor causing a large current through the brushes. The problem with this theory is I would expect the capacitor to fail totaly in a very short time. I think if it was mine I would confirm that a 100W bulb as a load behaved as expected with the switch in both forward and reverse positions. I would also try the motor fed with a variac and bridge rectifier to make sure that it worked OK at its rated speed.

Les.

[Savinay BhariParticipant @savinaybhari]

I would say it’s not a solid weekends work, as I have been dealing with this type of equipment for years wiring it up is about half hours job, longest time will be to make the bracket which would for me be like 2 hours. At the end you will have 2.5kw of power and enough torque to twist your arm off when geared right, presuming the lathes bearings can take it this is a huge upgrade

One thing he doesn’t mention is the setup is a sensor-less brushless setup, so if you load up the motor a lot the speed controller will only handle 10-20% drop in speed to recover back to set speed, say you stall it the speed controller will either pop or the motor will go out of time and you will hear a squealing noise (motor cogging), then you have to restart or reduce speed and increase etc, 90% of the time this will not kill speed controller but it will eventually blow. Or buy a sensored motor and controller like used on RC cars which will get rid of such issues.

Niel, motor and brushes are brand new and to be sure I tested each commutater pole on the multimeter for short and there wasn’t any problem, motor fault was my first thought. It run silly smooth on a 24V battery in both directions and the resistance on each pair of commutaor poles is same both next to each other and 180 degress apart

Les,

Motor is brand new from dealer,

• In forward motor jerks at every speed, I have measure the output at the first turn of the speed knob its about 6-12v the motor is still jerking, in reverse 6 to 12v no jerk, so I can tell you that the problem occurs in every speed on forward.
• In reverse I have gone to the full speed/ full turn on the knob, no issues.
• On a 12V and 24v batteries motor runs smooth in both direction by reversing the wires.

With a 100w GLS bulb the bulb goes to dim to bright smoothly in both direction, with no flashes what so every, this is why my fisrt post I was saying I ahe unique problem which I cant find on the net,

• Bulb plugged in all ok
• Motor plugged in not ok in forward only

Once again many thanks for all you help guys, truly appreciate your time and efforts

[Ketan SwaliParticipant @ketanswali79440]

Neil,

This guy has a Clarke CL300 lathe which is a C2 lathe. The motor brushes for his motor are different from the motor brushes for a C3 lathe. If he decides to buy the brushes, he needs: C2-150-MB Motor Brushes (Pair)…which are currently out of stock. He can always call Clarke – Machine Mart for the spares.

The machine in the link to which Shavinay refers is also a C2/family lathe. The link guys opening statement is: 'I have a Chinese mini lathe and it has the usual issue of breaking motors and control circuits', and then he refers to components for a C3 lathe…The C2 control board has no overload protection, and the C3 board does. The C2 motor is lower 'real output' wattage in comparison to the C3 motor. The guy in the wordpress link is incorrectly comparing apples with oranges, but I guess that he feels he is right.

Finally, just for clarification for those who are still following this thread, the C2 and the C3 are brushed motor, and the SIEG Super C3 is a brushless motor with again a totally different control board.

Ketan at ARC

[Ketan SwaliParticipant @ketanswali79440]

Savinay,

If you are intending to move away from your current arrangement to a brushless position, you may be right in your understanding of difficulties involved. Many 'electronically minded' people consider it to be a straight forward exercise. If it was so easy, SIEGs competitors would have offered something to compete vs the brushless range, but they too face the controller – torque relationship problems, and so far, they have failed to offer a brushless solution vs SIEG. I am sure that there are 'Hack Space – Blue Sky thinking – DIY options' out there, bla bla bla, some better than others, but most presentations are from 'electronic backgrounds'. Very few are equally mechanically matched in their experience, understanding, knowledge. I cannot say that they are right or wrong as I am not qualified in the electronics field, in the same way as such people are not qualified in the mechanical field!

There are many factors to be taken into consideration, and there are limited brushless DIY options which 'really' work, where knowledge is better balanced. Have a look at Blowlamps arrangements in this thread:

http://www.model-engineer.co.uk/forums/postings.asp?th=104732

and have a look at his album. His seems to be a workable DIY option you may want to look at. I donot know how well it works. This is something you may wish to ask him directly in this thread or over a PM.

Good Luck,

Ketan at ARC.

[steve salmonParticipant @stevesalmon32485]

Hi guys.

I am new to this forum, but it seams to be a valued source of information. I have a CL250 lathe, which has a problem, (surprise surprise). I have had the lathe a few years, and originally everything was running fine. After a while the motor/chuck, started to slow down, stutter and stop, and sometimes start again. Then it began a series of cycles, where it would be ok, work a for a while then do it's start and stop. Now it has begun to stop working for long periods, then work for a while and stop again. There is power, the lights work, including the overload and there is a slight hum when that is lit, (through the guard being up).

I have checked the brushes and cleaned them, (they are original).

Judging by previous posts, could the problem be with PCB, the motor or the speed controller?

I don't have warranty for it, as I have this for a good few years, any help on this would be appreciated.

[Les Jones 1Participant @lesjones1]

Hi Steve,
Intermittent faults are are always difficult to diagnose. I am not familiar with your lathe so can you clarify the statement that the overload light comes on when the guard is open. When the lathe is in a working state does this light come on when the guard is open ? (I would have expected the overload light to only come on if the motor is overloaded.) The wiring diagram I found online in the manual for the CL250 lathe does not show the overload light so I do not know how it should behave. Does the fault occur in both forward and reverse and at all speed settings ? Can you give some indication of what you mean by a long time ? (Several minutes, several weeks ?) When it is in the fault condition if you turn the motor by hand a few degrees does that cause the fault to go away ? The only thing I don't think is wrong is failed semiconductors on the control board. Other than that it could be loose connections, dry joints, faulty switch or relay contacts or an intermittent fault on the motor.

Les.

[steve salmonParticipant @stevesalmon32485]

Hi Les.

The overload light comes on when the guard is up, when in full operation. It is also comes on if I have the speed controller on and turn the direction switch on in either direction.

The fault does occur in either direction, and I have tried turn the chuck when it stops, but nothing happens.

At first the fault only lasted a matter on seconds, then minutes now its close to ten minutes or more. Judging by the previous posts, and for what I have surmised, it is either a faulty component, dry solder joint or the motor. But before I delve in to it, I thought it best to get some idea on what to look for. The manual I have is pretty much the same as the online version.

Steve

[Les Jones 1Participant @lesjones1]

Hi Steve,
If you wire in a DC voltmeter capable of reading up to 250 volts to terminals 1 and 2 of the control board next time the motor stops note the reading on the meter. If it is zero or a very low value then the fault is most probably on the control board. If the meter is still giving a sensible reading then the fault is either the motor or the wiring between the board and the motor. This includes the reversing switch. If you do not have a suitable meter you could use a low wattage (15 watts or less) mains voltage bulb. It MUST be a filament type bulb. (NOT low energy, LED or neon)

Les.

[Reece SloaneParticipant @reecesloane99868]

Hi all I'm new to this forum I have a conquest lathe that has been fitted with a Clarke cl300 controll box all was goo until today when I heard a pop and seen a flash from the speed controll knob or the f/r switch I'm not 100% sure it also blew the fuse in the plug I changed the fuse and now it runs at full speed in forward and reverse it will stop in the middle position and also if I the speed controll is set to off it will run at full speed if I turn it clockwise past the click it stopes I've had a quick look at the board and nothing stands out to me it's the fc250 board could if be the potentiometer any help wold be fantastic thanks

[john carruthersParticipant @johncarruthers46255]

Reece, I would hazard a guess that you have blown one or both power transistors (mosfets),. They both need to be replaced as a matched pair. You can test them in situ, if you look on the LMC site there is a pdf. on drive board testing.
**LINK**

[Les Jones 1Participant @lesjones1]

Hi Reece,
I agree with John that the mosfets have probably been destroyed by the original fault with the reversing switch or speed control potentiometer.. I would suggest trying to identify the original cause of the fault in the box with the reversing switch and potentiometer. It may have been some swarf that had got into the box and caused a short. If you cannot pin it down to the switch, the pot or swarf then I think it would be a good idea to replace both the switch and the pot as well as repairing the controller board. (Arc Euro Trade stock the pot and switch.)

Les.

[Reece SloaneParticipant @reecesloane99868]

Thank you both for your quick reply I am going to have a good look and may just change both the switch and potentiometer just to be safe does anyone know the model of the power transistors that I need to order thanks again for your help also how would I test the switch and potentiometer thanks best regards reece

[Les Jones 1Participant @lesjones1]

Hi Reece,
The MOSFETs are IRFP450 (CPC and Farnell stock them.) It is possible that other components could be damaged as well as the MOSFETs How competent are you at electronic fault finding ? DO NOT attempt to trace the fault using an oscilloscope UNLESS YOU POWER THE LATHE VIA AN ISOLATING TRANSFORMER. To test the switch and potentiometer for insulation breakdown you would need an insulation tester. (Set to the 500 volt range.) On the potentiometer you would be looking for breakdown to the metal casing from the switch and the track. On the switch you would be looking for breakdown between ALL permutations of contacts that are in the open position in all three positions of the switch. You would also be looking for breakdown between all of the 12 connections and the fixing bush. Even if these tests are OK there is still a possibility that an odd bit of metal is loose inside the switch that could cause an intermittent short.

Les.

[Reece SloaneParticipant @reecesloane99868]

I'm not too good a testing but am capable of soldering new parts on so I'll just change them aswell just to be sure

[Reece SloaneParticipant @reecesloane99868]

Just ordered 4x mosfits 2 sets just incase it happens again I'll give it a try when I get them thanks all

[Reece SloaneParticipant @reecesloane99868]

So I've just taken off the box and began to investigate the mosfits i have found that they are not exactly the same one is IRFP450 the other says FB F13 they don't look the same either could this be the cause of my problems at lease one has been changes also I have in my box a big black box that says FC-03H EMI FILTER I don't know what this is or if I need it any help on that would be great I also noticed that the solder joints of most wires are bare would I benifit from heat shrink on all of them thanks all

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