Hi,
You are so right Joe; I can't seem to tackle a simple project without it turning into a saga. Yes; repairing the Clarke speed control will be a most interesting project and couldn't come at a better time when I really need the lathe; what fun it is to study a circuit board and learn about Mosfet's right in the middle of another project which I was so focused upon? I'm just an ordinary guy with a single brain cell only able to focus on one job at a time so once again this clutch project is leading me astray.
What's this Joe; jumper off and sleeves rolled up; is it summer and did I miss it? A lump hammer and length of wood are very handy when all else fails.
Ted you are a gem; thanks again for your information; I spent a while looking at the Model Engineering site you kindly recommended and one thing I noticed was that these Mosfet's must be replaced in pairs?
What a surprise; I reckon one of these Mosfet's has expired previously because they are both different to each other and not paired?
I've now brought the control panel up into the warm well lit workshop and removed the circuit board ensuring all connections are clearly marked and a sketch made.
Assorted pictures.
As I was removing the leads a bit of black plastic material dropped onto the bench and I thought it must be from a casing so put it to one side; you are bang on Ted about this being a Mosfet problem because it couldn't have been easier to identify; the Mosfet had actually blown up and the bit of plastic was part of its casing.
Part of Mosfet casing and blown Mosfet.
I've taken lots of pictures because this is such a regular problem with these Clarke lathes so hopefully all the information will help others with the same problem.
The Mosfet's installed on my board are left hand; IRFP450 2J3S and right hand IRFP450 8A8B 9803 it's the right hand one that blew up.
You mention Ted that you have upgraded these Mosfet's previously? Could I please trouble you for extra information as to what Mosfet's you used and did you have to change the connections in any way; please treat me like a child because this is new to me although I'm a quick and willing student.
I've added a picture of the motor plate and this states the motor is 230VDC so would a 12V battery actually turn it?
Clarke motor plate and possible replacement motor?
Thanks for the information regarding the smoothing caps Refugee; I'll have to do a bit of research to locate which caps to change; I've noticed the small electrolytic caps and hopefully these are the ones which will be easy to purchase and install?
Assuming all goes well and I have the new Mosfet's and caps installed will I need to adjust anything because I've noticed pre-sets?
I feel happier now than I did when the lathe expired and if I can get it up and running again at little cost I think I'll keep this lathe as it is useful for turning small parts and takes up little bench space also it was a Christmas present from Bron. It's a pleasant little lathe to use but very; very slow on the bigger stuff.Once I get the clutch sorted then I can concentrate on restoring one of the Myford's.
Once I have the Mosfet details I'll order two pairs then I'll have spares.
It's a beautiful morning here so thanks Joe for sending it over.
Kind regards, Col.
Quick update;
http://www.datasheetcatalog.org/datashee...RFP450.pdf
You are so right Joe; I can't seem to tackle a simple project without it turning into a saga. Yes; repairing the Clarke speed control will be a most interesting project and couldn't come at a better time when I really need the lathe; what fun it is to study a circuit board and learn about Mosfet's right in the middle of another project which I was so focused upon? I'm just an ordinary guy with a single brain cell only able to focus on one job at a time so once again this clutch project is leading me astray.
What's this Joe; jumper off and sleeves rolled up; is it summer and did I miss it? A lump hammer and length of wood are very handy when all else fails.
Ted you are a gem; thanks again for your information; I spent a while looking at the Model Engineering site you kindly recommended and one thing I noticed was that these Mosfet's must be replaced in pairs?
What a surprise; I reckon one of these Mosfet's has expired previously because they are both different to each other and not paired?
I've now brought the control panel up into the warm well lit workshop and removed the circuit board ensuring all connections are clearly marked and a sketch made.
Assorted pictures.
As I was removing the leads a bit of black plastic material dropped onto the bench and I thought it must be from a casing so put it to one side; you are bang on Ted about this being a Mosfet problem because it couldn't have been easier to identify; the Mosfet had actually blown up and the bit of plastic was part of its casing.
Part of Mosfet casing and blown Mosfet.
I've taken lots of pictures because this is such a regular problem with these Clarke lathes so hopefully all the information will help others with the same problem.
The Mosfet's installed on my board are left hand; IRFP450 2J3S and right hand IRFP450 8A8B 9803 it's the right hand one that blew up.
You mention Ted that you have upgraded these Mosfet's previously? Could I please trouble you for extra information as to what Mosfet's you used and did you have to change the connections in any way; please treat me like a child because this is new to me although I'm a quick and willing student.
I've added a picture of the motor plate and this states the motor is 230VDC so would a 12V battery actually turn it?
Clarke motor plate and possible replacement motor?
Thanks for the information regarding the smoothing caps Refugee; I'll have to do a bit of research to locate which caps to change; I've noticed the small electrolytic caps and hopefully these are the ones which will be easy to purchase and install?
Assuming all goes well and I have the new Mosfet's and caps installed will I need to adjust anything because I've noticed pre-sets?
I feel happier now than I did when the lathe expired and if I can get it up and running again at little cost I think I'll keep this lathe as it is useful for turning small parts and takes up little bench space also it was a Christmas present from Bron. It's a pleasant little lathe to use but very; very slow on the bigger stuff.Once I get the clutch sorted then I can concentrate on restoring one of the Myford's.
Once I have the Mosfet details I'll order two pairs then I'll have spares.
It's a beautiful morning here so thanks Joe for sending it over.
Kind regards, Col.
Quick update;
http://www.datasheetcatalog.org/datashee...RFP450.pdf
Happiness is a wreck of a cabinet to restore.
