slow-poke
Ultra Member
The original motor in my CX706 was a 750 W brushed DC motor powered by KBIC type motor controller. I replaced the original motor with a brushless style.
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Fuse replacement -- CX-706
- Thread starter trlvn
- Start date
trlvn
Ultra Member
My front panel fuse, not the one that popped, is labelled 15A. I wonder if the CX706 was revised at some point to use a different speed control system and motor? On another board, a fellow mentioned that his CX706 came with a 10A fuse in the front and 15A at the back--the reverse of mine!
What does "KBIC" mean? Do these motors have a sticker showing the specifications?
The wiring diagram on the back of my machine says "Speed Control Board WEISS". Is WEISS a manufacturer or is this a style of DC speed control? A couple of quick web searches didn't give me a clear answer.
Craig
trlvn
Ultra Member
Again, I agree. OTOH maybe there is something else going on? For example, if it was somehow a 50 volt DC motor then it could only get to 750W at 15 amps, right?
Craig
TorontoBuilder
Sapientia et Doctrina Stabilitas
IF it were a 50v motor then yes to produce 750 watts you'd need 15 amp fuse.
BUT it is not a 50V motor. The standard is to use a 110v motor, and a rectifier bridge to convert 110VAC to 110VDC and then a circuit to either reduce the DC voltage in a brushed motor, or to chop up the 110VDC into pwm signal for brushless motor.
Busybee does not do anything out of the ordinary, they're too cheap and just go with the cheap usual option, so I'd bet $1000 it is not a 50v motor.
The other reason I know this is I've seen all the replacement motors on aliexpress just recently, they dont have your animal... but you are thinking whihc is great
Plug in hybrids are the answer. Smaller battery with onboard charging from the IC engine, all of the pluses of EV without the drawbacks of pure EV. Plug it in at night and the IC engine will rarely need to start.
Pure EV is not going to work out in the long run for Canada.
slow-poke
Ultra Member
I think the following answers all your questions.
Weiss makes machine equipment. Assuming your CX706 is the same as mine........
Note the motor current rating 8.3A, 750W/90V = 8.3A imagine that. However that ignores efficiency and I also question the 1HP rating. So the 10A fuse makes sense, if it blows too often I would consider a 12A.
Interesting comparison of 1HP brushed (large) vs. 2HP brushless (small)
KB board, there are many varieties, basic PWM DC motor controller, entirely possible that Weiss has cloned the original or put their sticker on an actual KB board.......
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trlvn
Ultra Member
@slow-poke Thank you for all of that.
Did you change the motor control board (or just a module on it) when you changed the motor from 1 HP to 2 HP?
One minor observation. The switches for the gear cover and chuck guard are both on the incoming 110 V line? I would have thought they would be on the low voltage side of the magnetic switch. Same effect but I thought the parts would be less expensive and safer on low voltage?
Craig
Did you change the motor control board (or just a module on it) when you changed the motor from 1 HP to 2 HP?
One minor observation. The switches for the gear cover and chuck guard are both on the incoming 110 V line? I would have thought they would be on the low voltage side of the magnetic switch. Same effect but I thought the parts would be less expensive and safer on low voltage?
Craig
slow-poke
Ultra Member
These boards are not isolated from mains, so there is no low voltage side to speak of, even the speed control pot has 200V common mode WRT earth.
I purchased the brushless motor and matching control board used from a forum member after he upgraded (to a servo I think). The new control board was close to the size of the original KB board, except it has a heat sink the entire size of the board, while the original has a tiny heatsink. So I cut a square hole in the sheet metal at the back so the heatsink is on the outside.
Looks like this
Attachments
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To a switch, 110 is low voltage. That aside, voltage isn't what kills switches - current is. So it's actually "potentially" less expensive and more effective on the 110 side. I say potentially, because I can't remember a switch that actually exploited the opportunity - but then again, I prolly just didn't notice.
ChazzC
Ultra Member
Also, having the main switch(es) on the AC side kills all of the power.
slow-poke
Ultra Member
The most important reason to break the circuit there is because your switching ac. Breaking 10A @ 90Vdc is just nasty in comparison, about 10x cost. Most power relays rated for 10 A @ 125 or 250Vac are only rated for 30Vdc, or if rated at higher DC voltage, then only at ma.
Quick Digikey search.....
Here is about the least expensive relay that will switch 10A @120Vac, $2.52
And here is the least expensive relay that will switch 10A@90Vdc, $26.14 (no stock)
In comparison to switching dc, ac is very easy, because the arc extinguishes on the first zero cross of the waveform, in practice not quite that simple with an inductive load like a motor, but you get the idea. Perfect example below, 10A@ 250Vac, but only 0.3A@90Vdc
Quick Digikey search.....
Here is about the least expensive relay that will switch 10A @120Vac, $2.52
And here is the least expensive relay that will switch 10A@90Vdc, $26.14 (no stock)
In comparison to switching dc, ac is very easy, because the arc extinguishes on the first zero cross of the waveform, in practice not quite that simple with an inductive load like a motor, but you get the idea. Perfect example below, 10A@ 250Vac, but only 0.3A@90Vdc
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trlvn
Ultra Member
Sorry, I didn't mean the DC side. Looking more closely, I guess the magnetic switch does not have a transformer for low voltage control. I have a bit of experience with magnetic switches that are maintained/energized by a low voltage coil. I forget the exact term but it is simple and common to have multiple NC switches and pressing any one of them (breaking the connection) causes the magnetic switch to open and kill high voltage power. These switches are low voltage and low current. Appears that the magnet in the magnetic switch is operated by 110V power.
Craig
Craig