- Joined
- Aug 18, 2023
- Messages
- 2
Hi all,
I've been lurking on the forum for a while now and hoped my first post would be something a little more helpful than this! I've been spurred to post earlier than expected this morning though as I've become absolutely stumped by some issues I'm having with my Crenex lathe and would love some opinions, if nobody minds. Thank you in advance for reading! I'll describe the symptoms as best I can and just leave out my own suspicions about what's causing it. I do have suspicions, but as my electrical knowledge is firmly 'amateur' I worry I could easily skew description by trying to guess. I have a friend who is much better at this stuff than me and he had a few helpful guesses, though wasn't sure himself. I'll add those in at the end.
I have a Crenex Mini lathe 8x16" 750W, they're all over eBay and I think many Chinese companies make the same one under different names - easy to find. Had it for a couple years with no issues, and used it responsibly.
A few months ago I began encountering an issue. During operation the lathe would suddenly switch off with an audible click. Sometimes it would turn right back on but most of the time it would take a few minutes. Sometimes ten or more minutes.
This problem became increasingly common. At first I thought it was just a dodgy extension cable that the lathe was plugged into. I replaced that and the problem persisted, so I began trying to diagnose.
During a test, the lathe suddenly turned off with another click, but this time all of the lights in the garage flickered on and off. Not enough to flick the breaker. After this the lathe would not turn on again.
Half an hour later I tried the lathe again and it did turn on, but suddenly whacked up to beyond full speed. It should have been running at 1250rpm but it was hitting 1700+, no matter how I turned the potentiometer. I immediately turned it off.
At this point I figured I had enough evidence to identify the problem as the mosfet. I removed the old one, tested it and discovered that it was indeed shot. I replaced it with a new one, turned the lathe on... and all was fine! For about 45 minutes.
I had 45 minutes of regular lathe use before the old issue came back. Garage lights flickered, lathe turned off. This time it won't turn back on - each time I hit the button the garage lights flicker, the click happens, and the lathe turns off. I've discovered that if I hold down the power button the lathe does start - the garage lights flicker but the lathe keeps turning. It always cuts out after a few seconds, however. At this point the lathe is essentially non-functional. During tests here, for the first time, the lathe freaked out enough to flip the breakers in the garage.
With my amateur electrical knowledge I'm pretty stumped. Would anybody have any ideas about what might be wrong and what I need to replace, please?
Finally, our own (possibly utterly wrong) guesses:
Before I replaced the mosfet I was wondering if it was either a capacitor or a power supply issue, though with the latter I didn't really know where to begin diagnosis. My engineer friend figured that the click we were hearing was a relay switching the lathe off to protect the circuit board. When the rpm went wild that immediately pointed us towards the mosfet, and that seemed to fix the issue for a short time, though it seems that all I did was treat a symptom of the problem, not the core problem itself. Now that the problem has returned and seems worse!
The way it takes a few moments to turn back on seems to suggest a capacitor discharging to me. Though my friend thinks it could be more a power supply, relay or motor brush issue. I did consider simply replacing the entire circuit board at this point, though if it's any of the latter things that may not help.
Thank you for reading, and I hope somebody has a better idea of what's going on than me! I've always avoided trying to deal with circuits in my time, knew it would catch up with me someday...
I've been lurking on the forum for a while now and hoped my first post would be something a little more helpful than this! I've been spurred to post earlier than expected this morning though as I've become absolutely stumped by some issues I'm having with my Crenex lathe and would love some opinions, if nobody minds. Thank you in advance for reading! I'll describe the symptoms as best I can and just leave out my own suspicions about what's causing it. I do have suspicions, but as my electrical knowledge is firmly 'amateur' I worry I could easily skew description by trying to guess. I have a friend who is much better at this stuff than me and he had a few helpful guesses, though wasn't sure himself. I'll add those in at the end.
I have a Crenex Mini lathe 8x16" 750W, they're all over eBay and I think many Chinese companies make the same one under different names - easy to find. Had it for a couple years with no issues, and used it responsibly.
A few months ago I began encountering an issue. During operation the lathe would suddenly switch off with an audible click. Sometimes it would turn right back on but most of the time it would take a few minutes. Sometimes ten or more minutes.
This problem became increasingly common. At first I thought it was just a dodgy extension cable that the lathe was plugged into. I replaced that and the problem persisted, so I began trying to diagnose.
During a test, the lathe suddenly turned off with another click, but this time all of the lights in the garage flickered on and off. Not enough to flick the breaker. After this the lathe would not turn on again.
Half an hour later I tried the lathe again and it did turn on, but suddenly whacked up to beyond full speed. It should have been running at 1250rpm but it was hitting 1700+, no matter how I turned the potentiometer. I immediately turned it off.
At this point I figured I had enough evidence to identify the problem as the mosfet. I removed the old one, tested it and discovered that it was indeed shot. I replaced it with a new one, turned the lathe on... and all was fine! For about 45 minutes.
I had 45 minutes of regular lathe use before the old issue came back. Garage lights flickered, lathe turned off. This time it won't turn back on - each time I hit the button the garage lights flicker, the click happens, and the lathe turns off. I've discovered that if I hold down the power button the lathe does start - the garage lights flicker but the lathe keeps turning. It always cuts out after a few seconds, however. At this point the lathe is essentially non-functional. During tests here, for the first time, the lathe freaked out enough to flip the breakers in the garage.
With my amateur electrical knowledge I'm pretty stumped. Would anybody have any ideas about what might be wrong and what I need to replace, please?
Finally, our own (possibly utterly wrong) guesses:
Before I replaced the mosfet I was wondering if it was either a capacitor or a power supply issue, though with the latter I didn't really know where to begin diagnosis. My engineer friend figured that the click we were hearing was a relay switching the lathe off to protect the circuit board. When the rpm went wild that immediately pointed us towards the mosfet, and that seemed to fix the issue for a short time, though it seems that all I did was treat a symptom of the problem, not the core problem itself. Now that the problem has returned and seems worse!
The way it takes a few moments to turn back on seems to suggest a capacitor discharging to me. Though my friend thinks it could be more a power supply, relay or motor brush issue. I did consider simply replacing the entire circuit board at this point, though if it's any of the latter things that may not help.
Thank you for reading, and I hope somebody has a better idea of what's going on than me! I've always avoided trying to deal with circuits in my time, knew it would catch up with me someday...
