# Need a little electromics help



## GrayTech (Oct 20, 2019)

Im trying to build an x axis power feed for my X2 mini mill. I have a sewing machine motor and its controller board. The board has a 5 pin plug that connected to other electronics to select thread style etc. I need to figure out how to bridge this as it wont work just disconnected. Ive included images of both sides of the board. I know there are some electronics wizard members here, so I'm hoping someone can help out. Electronics is not my strongest suite. Thanks in advance.


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## brino (Oct 20, 2019)

A little more detail might help......

Did anything on the 5-pins change the speed of the motor, the direction of rotation, or just on/off?

-brino


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## brino (Oct 20, 2019)

hhhhmmmmmmm.....

It looks like green and yellow wires send low-voltage DC power out that harness.

Can you read and post the device markings on IC1 (the three lead device closest to the 5-pin connector)?

-brino


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## GrayTech (Oct 21, 2019)

IC1 is... 
AUK
711
S7812PI

Not getting any motor movement when everything plugged in, AC power supplied and the 2 pins (CN6) for the foot pedal shorted 
I will test everything with a meter again tomorrow to make sure all parts are functional. Was running before i stripped it all from the machine.
Thanks brino


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## RobertB (Oct 21, 2019)

GrayTech said:


> S7812PI


That is just a voltage regulator.

I would not short the pins for the foot pedal. The pedal is usually a variable resistor not a switch. As brino asked, you need to determine what the function of the things the 5 pin connector went to are.


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## GrayTech (Oct 21, 2019)

As i understand the foot pedal (which i didnt get with the machine) is a potentiometer so i will use a potentiometer across those 2 pins at CN6.
I have exhausted google looking for wiring diagrams for that machine with no results so I'm trying to figure out the 5 pin. I dont want to just start bridging pins for fear of damaging the board.


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## RobertB (Oct 21, 2019)

GrayTech said:


> AC power supplied and the 2 pins (CN6) for the foot pedal shorted





GrayTech said:


> I dont want to just start bridging pins for fear of damaging the board.


???

The small block labeled PC1 appears to be an opto-isolator feeding the motor speed control circuit. It is hard to tell for certain because the white painted blocks obscure the traces on the PC board, but it looks like the opto-isolator is fed by the center (orange) wire on the 5 pin connector. Pretty hard to figure out what sort of signal should be going into there without knowing what that connector went to. Is it possible it went to another circuit board?

The SCR or Triac that controls the motor (next to the 120V label) is not mounted to a heatsink, so this board is for pretty intermittent duty, may not hold up well for your intended use.


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## matthewsx (Oct 21, 2019)

It might be cheating but here's a solution that doesn't involve wizardry. 






						Sydien DC6-60V 6V 12V 24V 48V 30A PWM DC Motor Speed Controller, Stepless Speed Regulation Start Stop Switch with Digital Display - - Amazon.com
					

Sydien DC6-60V 6V 12V 24V 48V 30A PWM DC Motor Speed Controller, Stepless Speed Regulation Start Stop Switch with Digital Display - - Amazon.com



					www.amazon.com
				




You might be almost this far into it just buying components and a case to put them in....

John


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## stupoty (Oct 21, 2019)

RobertB said:


> ???
> 
> The small block labeled PC1 appears to be an opto-isolator feeding the motor speed control circuit. It is hard to tell for certain because the white painted blocks obscure the traces on the PC board, but it looks like the opto-isolator is fed by the center (orange) wire on the 5 pin connector. Pretty hard to figure out what sort of signal should be going into there without knowing what that connector went to. Is it possible it went to another circuit board?
> 
> The SCR or Triac that controls the motor (next to the 120V label) is not mounted to a heatsink, so this board is for pretty intermittent duty, may not hold up well for your intended use.




I think the opto isolator is controlling the triac (might be a mosfet as I think the motor is getting DC) and the relay is used for reversing the motor as they are the only 2 components crossing the hi / low voltage sides.

I would be more helpful but my brain hurt a bit tring to figure out the location of components on the track side photo


Stu


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## RobertB (Oct 21, 2019)

stupoty said:


> my brain hurt a bit tring to figure out the location of components on the track side photo



You aren't kidding! 

The red wire from the connector looks like it controls the relay. The tan wire looks like it has no connection, but that white paint makes it impossible see for sure.

This may help, I mirrored the image of the bottom of the board and placed it next to the top. Maybe a fresh set of eyes can spot something else:


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## homebrewed (Oct 21, 2019)

I'm not seeing much in the way of "smarts" on that board.  Looking at the component side, the 3-terminal package just below the two caps on the upper right side of the board is a +12V voltage regulator (center pin is ground, bottom pin is the output).   The larger rectangle halfway down on the left side of the board looks like a relay.  I see what's probably a triac on the lower right side, and (perhaps) another relay near the bottom-center of the board.  

I don't see anything that looks like a micro-controller.  Maybe you're missing a board?


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## stupoty (Oct 21, 2019)

Hellow , very helpful 

green   = -ve low voltage
yellow =  +ve low voltage
orange = PWM input
Red     =  Relay input (connect to +ve low voltage to engage, interlock conection I think)
Brown =  Not conected ? I cant see a trace on the picture.


I did a little sketch , I might have traced something incorrectly if anyone sees an error, (I missed some of the details off, its a bit simplified)





Stu




RobertB said:


> You aren't kidding!
> 
> The red wire from the connector looks like it controls the relay. The tan wire looks like it has no connection, but that white paint makes it impossible see for sure.
> 
> ...


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## GrayTech (Oct 21, 2019)

Ive traced the 5 pin connevtor to the major components
Brown is unused

Green goes to + of both large caps and the left leg of the voltage regulator.

Yellow goes to - of both large caps and the middle leg of the voltage regulator.

Red goes to the relay and is connected to the right leg of the voltage regulator via a resistor.

So am i correct in assuming green and yellow fed power to another board that selected stitch styles etc and returned a PWM signal via the orange wire?


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## stupoty (Oct 21, 2019)

GrayTech said:


> Ive traced the 5 pin connevtor to the major components
> Brown is unused
> 
> Green goes to + of both large caps and the left leg of the voltage regulator.
> ...



The PWM  exactly as you say , the relay should connect directly to the supply (mostly) their should be a voltage rating on the relay itself , (sorry for polarity mix up  )   

You could use a simple Arduino example program to drive pwm from a variable resistor and as you say wire the relay to engage it.

Stu


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## GrayTech (Oct 21, 2019)

Thanks Stu
So i can do away with the low power section of the board, replace the relay with a switch and feed PWM to the opto isolator? Starting to sound doable for my limited electronics knowledge.


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## stupoty (Oct 21, 2019)

GrayTech said:


> Thanks Stu
> So i can do away with the low power section of the board, replace the relay with a switch and feed PWM to the opto isolator? Starting to sound doable for my limited electronics knowledge.




Yeah just wire to the jumpers on the low voltage side with a new pwm system , a switch on the relay might enable you to keep the pwm program very simple.  

one question i see is where is the red and brown wire going ? they look to be in the circuit that powers the relay , is their another switch they run to ?

Stu


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## matthewsx (Oct 21, 2019)

That board looks like it has a lot of smoke built up inside of it, be careful not to let it out


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## homebrewed (Oct 21, 2019)

Just be careful while putting your system together!  There's 120VDC present, with not much to prevent substantial current flow through various body parts.


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## Flyinfool (Oct 21, 2019)

It looks to me that the brown and red wires are connected together. 2 different switches that either one can turn on the relay.


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## Winegrower (Oct 21, 2019)

I've heard of design by committee, but so far not debug by committee.   This is a personal first.


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## brino (Oct 21, 2019)

stupoty said:


> one question i see is where is the red and brown wire going ? they look to be in the circuit that powers the relay , is their another switch they run to ?



I had convinced myself that the 2-pin connector with brown and red wires went off to an indicator lamp(LED?) mounted between the power cord and main power switch. @GrayTech can you confirm?

Also, what's the part number here:



-brino


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## RobertB (Oct 21, 2019)

brino said:


> I had convinced myself that the 2-pin connector with brown and red wires went off to an indicator lamp(LED?) mounted between the power cord and main power switch.



I think the 2 pin red and brown go to a jack that the foot control plugs into.


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## brino (Oct 21, 2019)

Thanks @RobertB, I still haven't see the "CN6" designator that was talked about above.....one issue with distance debug.....
-brino


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## GrayTech (Oct 21, 2019)

The thin brown and red wires go to the foot pedal to control the motor speed.

Part number requested is
G
FS10KM
9A7302

Brown wire in 5 pin harness is isolated as per continuity test, its not connected to anything on the board. 

Tested the motor with another driver I built for my bandsaw DC treadmill motor of same voltage and torque is not good at lower rpm. It will move the table fine but I dont think it will work well enough when cutting forces come into play. I'll use this 4000 rpm motor for another project and dig through my motor collection for something with more horsepower. I'd still like to get this board working though so not giving up just yet.


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## stupoty (Oct 22, 2019)

GrayTech said:


> The thin brown and red wires go to the foot pedal to control the motor speed.
> 
> Part number requested is
> G
> ...



The part is a 10 amp mosfet

The universal motors are normally quite high rpm, I have one on a precision drill press that is high rpm where it works well.  I think ur right about the low end torque without a big old reeducation geartbox.

Stu


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## RobertB (Oct 22, 2019)

Yeah, sewing machine motors are pretty anemic at lower rpm's. Even on a sewing machine where they have a pretty good reduction (about a 1/2" motor pulley and 4" to 5" machine pulley) at low rpm they often need a little hand assist just to poke a sharp needle through a couple of layers of fabric. Once you get that motor up above 5 or 6 hundred rpm they will zip right along.


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## Bi11Hudson (Oct 22, 2019)

Opinion only!!!!!! First job is to seperate the Electrical and the Electronics. The two are distinctly different areas of knowledge and not to be confused one with the other.

The motor is a generic sewing machine motor, _series universal_, with only two wires. What that indicates, to me, is that the motor is not reversable without an internal modification. The wires for the brush rigging and the stator must seperate at some point, leaving four (4) conductors to the outside. This applies whether it is run on AC or DC. The bottom line here is that the motor is not reversable as it is.

It can be connected either AC directly, or through a rectifier to get DC. Using AC, the speed is regulated with a reostat, like a pot but only two leads and heavier, stouter, and more expensive. I have a couple rigged to my Dremel and other electric drills where I can use my foot while my hands are busy. Or by using a triac to chop up the sine wave. Just like a light dimmer but rated for higher current.

Using DC, there are two (2) methods of control. The first using voltage control to control speed, with lower starting torque. The other using Pulse Width Modulation, to me the preferable of the two. PWM applies full line voltage (and current) in pulses, the width of the pulse controlling how much net power is applied.

Looking at your controller board at first glance, I am betting on a voltage controller. That's not to say for sure, just my first glance opinion. For use on a machine tool such as you indicated, my first instinct would be to find a different motor. A DC motor with a permanant magnet field would be best as it only uses two conductors. With a four wire motor, it would be preferable (highly) to reverse the armature, leaving the field the same polarity. This from the "old school" electric shop, not a hard and fast rule.

The main issue is that you do not need to use line (120) voltage equipment. An automotive window motor is reversable, albeit a bit large for your application. The important point is to have all external electrical equipment the same voltage so you can use a single power supply.

This doesn't answer your question directly, but with all the input you've been receiving it will give rise to some thought, if nothing else.

Bill Hudson​
.


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## RobertB (Oct 22, 2019)

Bi11Hudson said:


> An automotive window motor is reversable, albeit a bit large for your application. .



I used windshield wiper motors for mine. Both types have the advantage that they are geared motors with high torque and low rpm outputs. And both are very cheap, got my wiper motors for $10 each at a junkyard.
I went with the wiper motors because I knew they are designed for continuous duty. Don't know how a window motor would hold up. Their design use is only 3 to 4 seconds at a time.


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## GrayTech (Oct 22, 2019)

Thanks for all the input guys. This forum is awesome because its members are aesome. 
I forgot about wiper motots. They should be speed controllable like any other dc motor right? 
I have some AC speed controllers snd rectifiers. If i use a transformer it should be connected between the controller and rectifier correct?
I have heard that this method of speed control is hard on electric motors and smoothing capacitors help some. Any insight on this?


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## Bi11Hudson (Oct 23, 2019)

RobertB said:


> I used windshield wiper motors for mine. Both types have the advantage that they are geared motors with high torque and low rpm outputs. And both are very cheap, got my wiper motors for $10 each at a junkyard.
> I went with the wiper motors because I knew they are designed for continuous duty. Don't know how a window motor would hold up. Their design use is only 3 to 4 seconds at a time.



A wiper motor is *not always* reversable. It depends on a permanant magnet field as opposed to a wound field. A PM motor is reversable, a wound field motor is not, without all four leads coming out. The load on a machine tool is nowhere near as heavy as a window regulator. A window motor should run continuously fairly easily in that application.

Now, in response to the OP's second question; A transformer should *never* have DC applied to the input, so the rectifier should always be *below* the transformer. There are cases where a DC input is used, but those are considered rare. A X-former big enough for a motor drive will be expensive, I would recommend a switching power supply unless you are capable of winding your own x-former. I've done so several times but it is a PITA.

The speed control will come below the rectifier. Using a Pulse Width Modulation controller is highly recommended. It gives much more controllable speed control at lower speeds. Never apply an AC control, such as a light dimmer or router speed control, to the input of a transformer. It lets the smoke out of the transformer in short order. A PWM control isn't absolutely required, but is highly recommended. Mine come from M P Jones Assc, MPJA.com. Look for something heavy enough for two or three times the rated current, they are cheap enough. Motors are hungry when starting.

To reiterate, use a transformer from 120 to low voltage. Rectifier is next, the first item on the low voltage side. Then a capacitor, if one is used. This is the point to use a switching supply if that is prefered.  Then a speed controller. The motor can be reversed electronicly but I would prefer a relay. It only requires a (continuous) pulse to pick up and a small snubber cap to clean it up. And lastly the motor. 

A smoothing capacitor isn't really necessary on the input of a PWM controller, but does smooth things up a lot. Use a medium size, 500uF to 1000uF per amp. It still won't be battery smooth, but you won't notice the difference without an O-scope.

.


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## RobertB (Oct 23, 2019)

Bi11Hudson said:


> A wiper motor is *not always* reversable. It depends on a permanant magnet field as opposed to a wound field. A PM motor is reversable, a wound field motor is not, without all four leads coming out. The load on a machine tool is nowhere near as heavy as a window regulator. A window motor should run continuously fairly easily in that application.



This is true, though I haven't come across a wound field wiper motor since the early 70's. Even in the 60's when they were more common we used to make ride on kids cars and animated Halloween decorations with them by feeding the field wires out of the motor.  Plus when you go to the u-pull-it the wiper motors are easier to get to. Half the time they have the cars so close to each other it's hard to get the door open far enough to get to the window motors. (unless you can find a Saturn and then you can pop the plastic door panel off and get to the motor from the outside)


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## Bi11Hudson (Oct 23, 2019)

RobertB said:


> This is true, though I haven't come across a wound field wiper motor since the early 70's. Even in the 60's when they were more common we used to make ride on kids cars and animated Halloween decorations with them by feeding the field wires out of the motor.  Plus when you go to the u-pull-it the wiper motors are easier to get to. Half the time they have the cars so close to each other it's hard to get the door open far enough to get to the window motors. (unless you can find a Saturn and then you can pop the plastic door panel off and get to the motor from the outside)




In the original posting, the user stated that he didn't know much about electricity. My suggestions were geared to that (lack of) knowledge level. If he knows enough to find a permanant magnet wiper motor, that would be the better choice because of the heavier worm gear internally. The suggestion for a window motor was intended to have him avoid a *wound field* wiper motor.

I have a '68 dump truck (small, C-30) that I'm working on electrically. It has a wound field wiper motor with internal connections. I can bring out all 5 wires, *But* I don't want a *nonelectrical* user to attempt that while in the middle of figuring out the mechanical portion of his project. Being helpful without over complicating things was my intent. He has need of a simple *reversable* motor.

.


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## GrayTech (Oct 24, 2019)

Wiper motors it is. I'm ok with electrical its the electronics side that i dont fully understand. Would a PC power supply drive 2 wiper motors? And can I use a PWM module with it?
Thanks


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## RobertB (Oct 24, 2019)

Yes, PC power supplies are good. If you want a new motor or don't have a junkyard nearby try monster guts, they have new ones for $27 each.
If you want controller ideas, check out some of the Halloween prop groups, they have all kinds of solutions for wiper motors.

On mine I just use a 6 amp battery charger (you have to use a cheap manual one, not a smart one). Between the 12v 6amp, 12v 2amp, 6v 2amp settings on the charger and the hi and low speeds of the motor it gives me 6 different feed speeds. My original plan was using the charger temporarily until I got around to making a variable speed control. I've been using it that way for almost 20 years now and haven't had enough issues with the fixed rates to motivate me to change it to variable.


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## hman (Oct 24, 2019)

Here's a relatively cheap DC motor speed controller.  This plus a DPDT will get you reversible variable speed.  I've used either this one or similar ones several times.  They work well.  Ebay will have lots more.






						HiLetgo 12V~40V 10A PWM DC Motor Speed Control Switch Controller Voltage Regulator Dimmer for Arduino: Amazon.com: Industrial & Scientific
					

HiLetgo 12V~40V 10A PWM DC Motor Speed Control Switch Controller Voltage Regulator Dimmer for Arduino: Amazon.com: Industrial & Scientific



					www.amazon.com


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## Bi11Hudson (Oct 24, 2019)

My original thoughts revolved, and still do, around *reversable* motors. The (cheap) battery charger is an ideal solution. As well as wiper motors having the better torque curve and duty cycle. As long as the end user finds one with a Permanant Magnet field. An "X" axis drive will need to run in both directions on a regular basis, so this is a major concern. The supplier recommended above has reversable motors that would work.

Using a PC power supply *may* work, it would depend on the actual motor and the actual power supply. The simplist way to determine that is to hook up both motors with a moderate load and try to run both at the same time. The PC power supply will not be hurt, it simply goes into foldback when overloaded. Disabling the motors and a "Power on reset" will clear the power supply. If there is capacity to measure current, the motors can be tested under anticipated load before doing hookup.

Although the battery charger is an ideal solution, it should have a little capacitance on the output. While 1000uF per amp is suitable for many electronics, it isnt necessary here. With full wave rectification, such as the battery charger, the sine wave approaches zero at 120 times a second. Without a battery, it will _reach_ zero. The capacitor only needs to be enough to prevent this. 100uF per amp will serve, although higher would be preferable. I have a number of  4700uF, 65 volt caps on hand. Such would do quite well, probably exceeding the capacity of the battery charger. Lower voltage would work, but my experience calls for 3 to 4 times voltage capacity.

The PWM motor speed controls I get from Marlin P Jones are rated at 30 amps at a nominal voltage of 30 or so. Quite an overload capacity for this application. Any reversing function would need to be on the output of the PWM. A relay is best as it can be controlled with one output. (Plus ground/return) A DPDT automotive relay is fairly common, giving Forward-Reverse. Better still is two Double Pole relays, giving Forward-Off-Reverse capability. This of course would require two outputs, with a common ground. Above is suggested Amazon as a source. Jones is a little cheaper. Both are representative of the generic price, cheap.

.


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## sakuraki2k (Jan 27, 2020)

Can you kindly share the part name for the varistor under the fuse? Mine was blown by the fusd and totally damaged, and i can't see the part name to replace it. I could only make out GNR 10---K. Appreciate your help!


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## nnam (Feb 2, 2020)

It's a thermistor


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## Winegrower (Feb 2, 2020)

This is a remarkable thread.   After you guys finish with this, I have a friend who has a small brain tumor, and I have a 1/2" end mill that will reach it.   I just need some advice on how to stop the bleeding afterward.   And maybe how to hold his head still.   My vice only opens to 8".


I know, this is in poor taste.   Sorry.


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