ct128 Lathe won't stay on

[Darren Beausoleil]

Hi everyone,

I'm hoping someone might know of a better solution then buying a new lathe. I have a CT128 Lathe and it has 2 major problems that might be tied together. The first and most important problem is the lathe if and when I can turn it on often likes to turn itself off. I have seen it where I press the on button and it does nothing. Other times I press the on button and it goes click, the rpm display lights up and then power shuts off. Other times I'll press the power button and it will work fine for awhile then if I stop turning I take the risk of it shutting off by itself again.

Attempted fixes: Pressed all the reset buttons. Tried unplugging and plugging back in, Tried the off button and then the on button. Latest attempt; I took the panel apart and used compressed air to blow away and specks of dust if any. It looked very clean. I checked all connects, they appear solid. Also I attempted to turn it on while I had the panel open and when it did turn on for a brief moment I could hear a sizzling sound. Like bacon in a frying pan.

2nd problem is the lathe has a speed control that allows one to change the speed from 0-1200 on low and 0-3200 on high, however I start at 0 and it doesn't do a gradual climb it will jump from 0 to 65 then maybe 150 and up more again to 300. It isn't doing the gradual climb by 5 increments like it should and when you have a rough 17" bowl turning at 400rpm instead of 50 it can be scary.

Everything I've seen online is saying the CT128 is now a really big paper weight. Any help would be appreciated,

Darren

[Jason Edwards]

That lathe was an 18x47 and painted different colors and sold under a variety of different names depending on what country you are in. My guess is you're from Canada. Have you tried calling Busy Bee or Craftex tech support? In the US, it was sold under the Grizzly brand. You might try calling them too.

[Bill Howatt]

Jason has pointed you in the right direction. Your description seems to point in the electronics - the controller "board" being the most likely culprit. If it is, then the two problems you likely will have are if a repair/replacement is available and if so, is it worth the cost for that lathe.

Edit: Just had a look at the user manual and it looks like this lathe has a brushless DC motor which means it has sensors providing feedback to the controller board. In short, I'd add a "it could also be the motor" to the list of suspect causes. My impression there was a lot of problems with brushless DC motors on lathes and some reverted back to VFD/3-phase drives - just my feeling!

[Darren Beausoleil]

Thanks guys,

I am in Canada. I just got off the phone with Craftex/Busy Bee Tools technical support and the best they could do is tell me that it might be the inverter board and they don't make those anymore so I can't get a replacement. He suggested if I know of an electronics store that I can bring the inverter board to and have them look at it to see if they can find and fix the issue with the board. That was all the info the guy could provide me with. I don't know of any electronics repair stores in my area, I'll google it but I don't have high hopes.

Darren

[Richard Coers]

I have no idea what a CT128 is, but since Bill did the research and discovered it is a DC motor, you can buy an entire new controller on Amazon for $200. You have to buy a horsepower resistor as well, so actually a little more money. https://www.amazon.com/dp/B00RW7LSXM...v_ov_lig_dp_it

But first I would replace the brushes and check any switches for sawdust in them.

[Darren Beausoleil]

Thanks Richard,

I checked out the DC control box and looked up the resistor. I'm a bit confused, would I have to open up the control box and insert the resistor? and which resistor would I even need? Sadly when it comes to the inner workings of my lathe I'm at a complete loss. I did however find a guy who can take a look at the inverter board. He isn't sure how much help he will be but he will be able to see if the resistors are in good working order or if they are burnt out. Fingers crossed that they are just old and burnt out. When I talked to him he said they are normally only good for maybe 10 years. I'll keep everyone posted when I find out more.

Thanks,

Darren

[Richard Coers]

Thanks Richard,

I checked out the DC control box and looked up the resistor. I'm a bit confused, would I have to open up the control box and insert the resistor? and which resistor would I even need? Sadly when it comes to the inner workings of my lathe I'm at a complete loss. I did however find a guy who can take a look at the inverter board. He isn't sure how much help he will be but he will be able to see if the resistors are in good working order or if they are burnt out. Fingers crossed that they are just old and burnt out. When I talked to him he said they are normally only good for maybe 10 years. I'll keep everyone posted when I find out more.

Thanks,

Darren

You've given zero information about the motor size, I don't want to advise you with a guess. Google is your friend, https://pim.galco.com/Manufacturer/K...md-240d_im.pdf

[Darren Beausoleil]

Thanks for the info,

Motor info: 220V class F
12A IP54
3500r/mm P2 =1500W
Made in China
That's all the info on the motor sticker, some I understand most means nothing to me.

Darren

[Bill Howatt]

The regular DC motor controller will not work with a brushless motor they are a different design that have sensors embedded to feed back digital information to the controller. There are 4 power driver lines sending power to the motor.
There is a schematic diagram on P22 of the manual if you are interested: https://www.busybeetools.com/content...uals/CT128.pdf

[Darren Beausoleil]

UPDATE.... Its alive! I found a guy who works on circuit boards and I brought him the whole headstock. He found in the inverter power box had several issues; solder missing or lacking in some places but the main issue was the previous owner had replaced some resistors and 2 of the 6 were reversed.

After fixing that my guy took apart the encased power switch and found that the connectors were corroded because the resistors were installed wrong. He cleaned up the switch and now the lathe works like new. By fixing the main issue it also fixed the speed control problem I was having too.

Thanks for all the help and advice,

Darren

[Richard Coers]

UPDATE.... Its alive! I found a guy who works on circuit boards and I brought him the whole headstock. He found in the inverter power box had several issues; solder missing or lacking in some places but the main issue was the previous owner had replaced some resistors and 2 of the 6 were reversed.

After fixing that my guy took apart the encased power switch and found that the connectors were corroded because the resistors were installed wrong. He cleaned up the switch and now the lathe works like new. By fixing the main issue it also fixed the speed control problem I was having too.

Thanks for all the help and advice,

Darren

I'm quite skeptical that incorrectly installed resistors causes corrosion. Google said they can't be installed backwards. Edit; After all, many capacitors, which are sometimes confused for resistors, are polarized and must be placed properly within a circuit. But resistors have no polarity. Current passes equally through from either direction. That means you can't install them backward. https://www.axcontrol.com/blog/2021/...em%20backward.
Also since the machine was running, how could that be with incorrect installation of components. I'd suggest you you had cleaned the switch at the start of trouble, there would be no need to get inside the box.

[Bill Howatt]

Correct, resistors have no polarity and can be installed either end for end. Modern electronic components sometimes aren't as obvious as the old ones in terms of identifying what they actually are but I would have thought a capacitor of sufficient size to require a polarized one would be identifiable. It could be the repair guy miss-spoke or was wrongly understood.
I don't know but I'm not as confident as Richard that cleaning the switch would have been sufficient to fix the problem.

[Darren Beausoleil]

I must have understood wrong. It must be the capacitors and not the resistors. my lathe has 6 items that the previous owner had added to the machine and they are about the size of a "C" battery. They have wires that they had soldered to them and then to a spot on the inverter board. The guy I brought it to showed me on the board where they were soldered and pointed out which ones have a solid white line on the board and told me that is where the positive or the negative goes (I don't remember which) but whatever one is supposed to be there the previous owner had the wires reversed. I hope that clarifies my messy explanation.

Darren

[Bill Howatt]

Yes, something that size and shape with a polarity is a capacitor. Capacitors are a known "thing to check" in power supplies that convert the incoming AC to DC and then use the DC to power the circuits where it gets chopped at a higher frequency and filtered with capacitors again. As they age they loose their capacity for various reasons like leakage and the resulting DC output from the rectifier isn't as good to power high current loads among other possible problems. Note that these switching power supplies are very common throughout electronics these days such as in TV and computer power supplies; your phone charger is a small one and they are liked because they eliminate the need for bulky and expensive transformers.