Craftex B1979C 7x8" lathe troubles

Nitrous

Active User
Registered
Joined
Apr 23, 2014
Messages
36
Hi guys,

i recently purchased an older (white powder coated) lathe with some unexpected problems. Specifically, the motor appears to be intermittent.

Im going to crack open the control box to make sure there isn't any specific loose wires etc but is this well known controller board problem I should simply replace?

i have a few things I have to order from LMS (gear cover; a longitudinal feed knurled handle; tool post detent) so would be helpful to get some feedback.

Any advice is appreciated.

Thanks
doug

the three photos show the board, the error state and the running state. Nothing on the board looks obviously BO'd, but electrolytics can dry up, leak etc.

image.jpg image.jpg image.jpg
 
Last edited:
not knowing anything about your lathe, i would be suspect of the motor brushes.
you may need to remove the motor to remove the brush holders to inspect the brushes.
testing the boards transformer output would be a secondary test for me anyway.

if there are no obvious burn or scorch marks, i would be suspect of a voltage regulator or possibly a resistor opens electrically under thermal expansion. (the part that is on the heat sink in the left middle of the picture is a voltage regulator)
you can, of course, test individual components on the board as well.

electrolytic capacitors are susceptible to failure as you had mentioned before,
they are usually easy to spot-
they will either be bulged out, have a cracked outer encasement sleeve , or have goop leaking out.

if you really have issues and can't seem to repair the board(if that is the problem), you can replace the board with a Pulse Width Modulation Control board commonly found on Ebay and other sites.
you would just need to know the volts and amps or of the motor to find the replacement PWM controller board.

good luck
mike:))
 
Mikes points are good, the cap's usualy look blown as he says.

depending upon the age of the lathe might be worth continuity checking all the cables incase their. Has been some corosion inside them (water or acidic fluid drawn in to them).

i used to get swarf sucked into the air intake on the motor of my 9x20 , worth giving the motor a quick open and clean(if its easy).

I've also had the green go button become faulty on the old lathe, sometimes it would just drop out or not turn on easily.

Stuart
 
Last edited:
A +1 to what Ulma Docotr has said. Also, check the board for cold soldier joints. It’s best to get an eye loupe and good lighting when looking for cold solider joints. And take your time, they can be hard to find and not always obvious…Good Luck, Dave.
 
A +1 to what Ulma Docotr has said. Also, check the board for cold soldier joints. It’s best to get an eye loupe and good lighting when looking for cold solider joints. And take your time, they can be hard to find and not always obvious…Good Luck, Dave.


Thanks guys,

i popped the the motor off and checked the brushes. Pretty warn but flattened then out a bit and the motor spun up without trouble. The red light that comes on when the board goes dead appears to be a current limiter LED. Reset is by powering down the board. When I reassembled it, the motor runs nicely, although at very low RPM, I can stall out the motor leading to a reset condition.

Are these motors so gutless that they overload that easily, or is this a low rpm torque issue?

The PWM board idea might be a worthwhile upgrade. The motor is 250watt at 110VDC. The system is based on a 110v AC standard. It's actually a dual voltage board.

Ive ordered replacement brushes. I think for the $300 I paid for it, it will be worth putting some time into it.

Thanks again guys,
doug
 
Hi Doug, I am in Stoney Creek area.

I have a B1979C myself and have done extensive mods to mine.

note:
that these asian lathes had many different circuit boards depending on the production year and the original manufacture. I tried doing some research on the boards a few years ago but came up with little or no consistent answers. At worst case watch Ebay for a control board for parts. or do a complete change over to another system from another asian mini lathe. Grizzly , Seig C3, Harbor Freight , you get the idea.
Keep in mind that these were produced with the cheaper end of the parts spectrum lol , check everything in the control box, all switches reset, all the connections solder joints. you may find a poorly soldered joint on the board. hard to say.
Nutech electronics here in Hamilton ( on Parkdale Ave.) has or can get any board parts you need.

Mine is a fairly older model. I have had to change the potentiometer, and the caps in mine.

A brush change is a good idea,
was yours working well before this issue or ?
have you checked the pot on yours ?
is it inconsistent ?
I have an extra pot if you need one.

Feel free to contact me if you have any Questions. hope this helps.
 
Hi Doug, I am in Stoney Creek area.

I have a B1979C myself and have done extensive mods to mine.

note:
that these asian lathes had many different circuit boards depending on the production year and the original manufacture. I tried doing some research on the boards a few years ago but came up with little or no consistent answers. At worst case watch Ebay for a control board for parts. or do a complete change over to another system from another asian mini lathe. Grizzly , Seig C3, Harbor Freight , you get the idea.
Keep in mind that these were produced with the cheaper end of the parts spectrum lol , check everything in the control box, all switches reset, all the connections solder joints. you may find a poorly soldered joint on the board. hard to say.
Nutech electronics here in Hamilton ( on Parkdale Ave.) has or can get any board parts you need.

Mine is a fairly older model. I have had to change the potentiometer, and the caps in mine.

A brush change is a good idea,
was yours working well before this issue or ?
have you checked the pot on yours ?
is it inconsistent ?
I have an extra pot if you need one.

Feel free to contact me if you have any Questions. hope this helps.

Are you a member of any local model engineering clubs?
im just getting back into hobby machining.
Doug
 
Hi Doug,
no I am not.
I'm more of a home hobby guy.
 
Back
Top