speed control pcb for Clarke CL300 lathe

[MuzzerParticipant @muzzer]

I expect the design is fairly tolerant of different types of FET. The IRFP450 is an old, easy-to-drive device. As long as you are certain that each device needs to be a FET, fit a 450. They are usually identified as "Qxxx" or TRxxx". The main issue is likely to be damage beyond the FETs themselves. When these devices fail, you often get a big voltage coming out of the gate which blows up the drive circuit. It should be fairly obvious if this is the case when you first turn it on after repair!

The EMI filter is just for filtering out electrical noise to stop it getting back into the mains. Leave it where it is unless you want problems with your other electrical equipment (and the neighbours). I expect a fuse will have blown somewhere. You should try to replace it with a similar speed fuse too, as well as the correct current rating. This will help to limit damage if there are any further "events".

Murray

[Les Jones 1Participant @lesjones1]

Hi Reece,
I do not believe the difference in the mosfets is the cause of your problem. The fact that you saw a flash from the box that contains the speed pot and reversing switch indicates that there was a large spark in there. This is probably the cause of the mosfets failing. The EMI (Electromagnetic interference ) filter will either be in the mains feed to the control board or between the control board and the motor. It is to reduce interference caused by the PWM switching being radiated or fed back into the mains. The fact that the solder joints are not sleeved should not matter. (So long as they are not shorting to other points or earth.)

Les.

[Reece SloaneParticipant @reecesloane99868]

hi all just wanna say a big thanks to all the people that helped me with my lathe control board problem mosfets arrived this morning changed them over and all is good hope it last

[Les Jones 1Participant @lesjones1]

Hi Reece,
The mosfets failing is not the cause of the flash from box containing the reversing switch and speed control potentiometer. They failed as a result of the flash so if you do not fix the cause of the fault it is likely to happen again.

Les.

[KhefinParticipant @khefin]

Evening chaps!

As a person who lurks a lot, I feel that it's time that I add my first post that may prove to be of use to someone.

I have repaired my own C3 FC250J control board several times over the 12+ years that I have owned it. In fact, I have just finished repairing it again after it surviving for just one day! I too have had a flash-bang on several occasions, including the past two failures. Close examination and careful troubleshooting has revealed nothing pointing to the root cause… Until now…

Today I decided to remove the Toggle Forward and Reverse switch after testing it thoroughly with no signs of failure and dismantle it (it was the last thing I touched on Sunday's failure with a flash-bang, after using the lathe for several hours), Within the switch, I found clear black sooty evidence of contact arcing. On closer examination I could see tiny pieces of swarf along side the contacts in the switch. Examination with a magnifying glass revealed some tell-tale pitting in the switch's insulation where I assume that swarf had vaporised. So if my deduction is correct, swarf has entered the switch body over time through the switch's open neck, eventually building up to form a bridge across the switch's forward/reverse contacts (the centre two contacts on my toggle switch). So when you flick the Forward and reverse switch you get an instant short with a flash-bang that destroys the MOFETs and the swarf is vaporised leaving a perfectly functioning switch… Until the next build up of swarf!

I have cleaned and reassembled the switch carefully, refitting it to the case after replacing MOFETs (again). The controller is functioning well on the bench. I will refit it to my lathe tomorrow.

As my lathe never had a waterproof cover fitted to the forward and reverse toggle switch, I shall purchase one and fit it as soon as possible. I advise others to do so if their lathes have the same type of switch and those who have the cap fitted ensure that it is in good order! Hopefully such simple remedy will prevent swarf entering through the open neck and causing the momentary short across the switch contacts and destroying the MOSFETs again.

I suspect that this is why Sieg has fitted rotary switches to some newer models of the lathe.

Hope the above helps someone out there.

Kevin

[Savinay BhariParticipant @savinaybhari]

hi Guys,

can some one take a look at this video please and let me know if the sound coming from the PCB is normal, this is with just a light bulb connected to the output, there is no motor connected. but there is a loud buzzing coming from the PCB this buzzing increases with the increase in the potentiometer turn clockwise and occurs both in reverse and forward. is this normal?

the last board that i had definitely did not make this loud a buzzing, this is scary loud just running a light bulb, is there something wrong here or is this normal? would appreciate your views guys thanks in advance.

Video;

Edited By Savinay Bhari on 12/01/2016 18:22:32

[Barry Williams 2Participant @barrywilliams2]

Does anyone know what the DC operating voltage of the Clarke CL300 motor. Just acquired the lathe but it has no control board, covers or buttons and switches but the motor and drive belt came as part of the deal.

Though I would try connecting the motor to direct mains via a 10 Amp mains rated bridge rectifier to see if it is OK before I start buying boards etc.

Many thanks

Barry

[Neil WyattModerator @neilwyatt]

Posted by Barry Williams 2 on 08/03/2017 17:31:50:

Does anyone know what the DC operating voltage of the Clarke CL300 motor. Just acquired the lathe but it has no control board, covers or buttons and switches but the motor and drive belt came as part of the deal.

Though I would try connecting the motor to direct mains via a 10 Amp mains rated bridge rectifier to see if it is OK before I start buying boards etc.

Many thanks

Barry

It would run, but it will be far too fast of 99.9% of turning.

If you just want to check the motor works, a good 'un will run smoothly on a 12V car battery or charger.

Neil

[John RuddParticipant @johnrudd16576]

Operating voltage is a function of motor rpm or vice versa….usually around 180v dc…

From experience…..

Checking the motor on a 12 v supply isnt conclusive….if there is a resistive connection at the comm this will manifest itself as excessive sparking across the comm/brush junction as the voltage is wound up…close examination required of the copper winds as they meet the comm will show if the armature has been subject to high temps….( enamel coating discoloured-blackening…)

Best way is to use a variac with a full wave bridge with meter monitoring the voltage applied to the motor.

[Barry Williams 2Participant @barrywilliams2]

Thanks for your speedy responses Neil and John but I just tried the motor on 24V DC and it seems there are a number of open circuit wires on the armature even though they do not look or smell burnt. Suppose the control boards went the same way as the motor !!

I have a 240V AC motor out of a Flymo rated at 400W and it has a bridge across the field windings, so it looks as though it might be reversable but need to find a suitable speed controller now and a method of fitting my alternative motor as it is slightly larger than the original motor.

Many thanks

Barry

[John RuddParticipant @johnrudd16576]

Barry,

The speed controller can be tested by using a 100 watt light bulb in place of the motor……

With everything connected as normal, use a light bulb in place pf the motor, the speed pot will vary the light intensity of the bulb…

[John HaineParticipant @johnhaine32865]

The flymo motor is probably a series wound universal type and if so would not be suitable for driving a lathe.

[Ian S CParticipant @iansc]

If your lan mower is anything like my one, the motor would be a 2 pole, single phase induction motor (2800rpm), not suitable for speed control.

Ian S C

[Barry Williams 2Participant @barrywilliams2]

Hi John H and Ian, I am getting a bit lost now as to my motors suitability but mine is off a fairly old Flymo hover mower and after further investigation (mainly digging out the old grass cuttings!) it is a DC motor, as the mains 8A bridge rectifier DC outputs are connected to the end of each field winding with the armatures carbon brushes across the other ends of the field windings, so it becomes field winding – armature – field winding which I believe is a series, self exiting motor set up. No rating plate giving any idea of speed etc, so guess I will have to try powering it up first and measure its RPM at 240V before going any further.

Good news is that despite a rough 6002 ZZ front bearing this motor runs fine on 12V DC and it seems to have good torque.

Barry

[John RuddParticipant @johnrudd16576]

Barry,

It is still a universal motor, not dc.

A dc motor would have permanent magnets for the field similar to the lathe motor.

Some motors ( and I've not seen one…) have seperate field windings that are fed with dc and the speed varied by applying adjustable voltage to the armature….drawback with this method is that when the armature isnt spinning, the field can become warm/ hot ……( KB controllers can use this method of speed control for dc motors that are not pm motors)

[Barry Williams 2Participant @barrywilliams2]

Thanks for clearing that up for me John. Looks as though I will have to keep on searching the auction sites etc for a suitable motor but I am a little reluctant to go the route of purchasing original Clarke parts, as there seem to be so many with motor or board issues.

Regards

Barry

[Neil WyattModerator @neilwyatt]

Barry, take a look here:

http://www.model-engineer.co.uk/news/article/3-phase-conversion-and-other-alternative-methods-of-powering-a-mini-lathe/18752

Neil

[Andrew FarrowParticipant @andrewfarrow93608]

CL 300 M Metal lathe speed control.

I too have been through the speed control saga. Having been quoted over £160 by Machine Mart (somewhat cheaper elsewhere) for a new circuit board and not convinced this was the cure I looked for other options. Following advice from above and from other sources I replaced the MOSFETS and although the speed control now worked it only lasted a short while.

On eBay I found an ac to dc speed control DLM DC-51 rated 400w, even allowing for Chinese exaggeration that should do the job as the CL 300 is rated at 300w. At around £18 it was worth a go.

The controller is smooth in operation and has been working well for a little while now, although I have not done any heavy work so it has not been too stressed, but it looks promising.

A couple of points; make sure you purchase the 400w as there are lower rated. There is no reverse function but you can wire into the dc output lead a reversing switch (double pole double throw). The control has an illuminated main switch but a stop switch can be wired into the main supply, in which case I would position it to the right hand side or on the floor. Note the warning to use the variable control not the on/off switch.

I made a casing and mounted the control, intact, close to the original position, although you could try gutting the original casing and transferring the new components but of course you would loose any warranty.

Keep on turning.

Andrex

[Eric FlemmingParticipant @ericflemming88494]

I have a fc200b controller board. I blew one cap 47uf at 50volts. but don't know which way it went on the board. Any one have one of these controllers?

[Felix CantesanuParticipant @felixcantesanu73894]

Hi all, I just spent some serious time reading this forum as I have a problem with my Clarke mini lathe. Everything was working great (10 years going strong) until I switched the main switch to Reverse. I've been using it fro years on Forward only…probably some brass material (I mainly work with brass tubing) got in there and once I turned the switch on the lathe came on, full speed, then cut off…a bit of smoke came out from the controller box… I took it apart, cleaned the switch the best I could, replaced the fuse, but the fuse quickly blew again as soon as I plugged it in. Thinking the switch was bad, I went and bought a new one, did all the soldering, new fuse…same result: as soon as I plugged it in, without toughing anything the fuse blew. I took the board up, noticed a clear spot where the initial burn happened (black splash on the plastic and a fried up link on the board), I replaced the missing board link with some thin copper wire, all looked good…very hopefully I put it all back in, new fuse, plugged it in; same result… I'm good with mechanical stuff but electronics clearly aren't my forte. Any ideas for me? Should I just buy another complete board? Perhaps retire the ole lather and get a new one? I use this for work and am quite incapacitated without it! Your ideas greatly appreciated! Best, Felix.

[John RuddParticipant @johnrudd16576]

See my post further up, testing the board with a 100watt light bulb…….cheaper than a new board/lathe as a first step…..

[Rik ShawParticipant @rikshaw]

These speed control boards seem to fail all to often. Mine did on a number of occasions. A WARCO engineer told me that it is ESSENTIAL to back of the speed control to zero before starting the machine in order to prolong the life of the board. (Poor design? – almost certainly is my guess.) It even advises this in the machine manual but I think that this advice should be in inch high block capitals and printed in red.

My final solution was to flog my lathe and buy something without electronic speed control. OK, its a PITA changing belts and back gears to change speed but I no longer have the constant worry that the thing will go "PHUT" on me when I switch it on.

Rik

[John RuddParticipant @johnrudd16576]

Felix, Are you UK based? If so, whereabouts?

[Felix CantesanuParticipant @felixcantesanu73894]

 

 

Posted by Rik Shaw on 25/05/2018 09:47:00:

… it is ESSENTIAL to back of the speed control to zero before starting the machine in order to prolong the life of the board.

Rik

I always did have the control knob at Zero. It was at Zero when I flicked the switch to the Reverse…then lathe just went crazy, full speed on! Weird.

John, I am not in the UK. I'm actually in Western Canada, although I was in Eastern US when I bought the lathe.

After installing the new switch ($40) and the same problem persisted I pulled out the board, saw the burn mark and burned board link, fixed that….but still same problem: as soon as I plug it in to power it blows up the fuse (to be sure, I bought fuses that looked like the original: 4Amp 250V – is this the right fuse?).
So I cannot test the board on the lathe, or a 100W bulb for that matter…there must be a short somewhere that blows the fuse immediately upon plugging it to power (I've used up 5 fuses already LOL)

 

 

Edited By Felix Cantesanu on 25/05/2018 16:44:38

[John RuddParticipant @johnrudd16576]

Felix,

Does the fuse blow straight away with motor disconnected?

Has the board got a part/model number on it? FC250/350 …..a photo would help..

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