Dc power supply in cnc not working

[eccerr0r]

Re: Dc power supply in cnc not working

Don't know how tolerant your circuit is of faults such as this... but you aren't blowing it again when testing?

[sam_sam_sam]

Re: Dc power supply in cnc not working

Updste...i was pretty confident that stepper motor good so i connect suspect stepper to othet stepper driver and it works good

The other 2 stepper motors work fine as long as the bad driver board is not connected to motor

So im pretty sure its a bad driver board bad L298...like i said i think these are failing due to age and or environment...unheated garage can get to -10f some winters although specs say L298 can handle up to -40C so temp should not be issue..prob just age issue

Here is a pic of board i just remove..im going to replace the L298 today..i bought several last year knowing this could be a constant issue since machines are so old..these boards are obsolete and can not be obtained anywhere..they can only be repaired..thankfully they are old school and all the componenets are replaceable....

and dont laugh at how i replace the L298....i use an odd technique....since these boards are obsolete not avail i cant risk ruining it and since desoldering the multipin chip is not easy for me i just cut legs carefully with a small hacksaw blade and resolder in the new one on top of the orig legs...it doesnt look good but it works and reduces my risk or ruining several pads etc...

It possible that it blew the 10 amp fuse if was a fast acting but would have mean that the stepper motor controller ic chip would have to be in direct short mode do I think that what happened maybe but something else happened at the same exact time what else happened nobody will know for sure

I meant to ask you earlier what do the stepper motor do on this machine is for axis movement

[shelby5041]

Re: Dc power supply in cnc not working

Update..replaced L298 and it working now

Fyi the main 110v fuse is 2 or 3 amp only

Yes axis movement...This is a small cnc milling machine

You can online search labvolt 5600 mill

[shelby5041]

Re: Dc power supply in cnc not working

Thank you for all the help

[eccerr0r]

Re: Dc power supply in cnc not working

If you keep frying those L298s that means the circuit is not tuned right. Suspecting the heatsink of the L298 is roasting.

So basically it's a poorly designed circuit. So I guess if you have a whole pile of L298's you'll be good till you run out...

[shelby5041]

Re: Dc power supply in cnc not working

Hi

There is a big 12v fan also cooling the stepper driver boards

its a bit deceiving...they really dont keep blowing ...they just are since i got the machines
..these mschines are 25yrs old...with original everything...no parts were replaced until now

I bought these from a guy 2 years ago...they were sitting around in a shed idle for several years in rough shape but they are very well made machines...and made in USA...even the electronics boards were made in usa

So now that i have them and refurbishung them ...bringing them back to life...some of the suspect / end of life components are failing ..ive replaced 2 stepper motors and 3 stepper driver board L298s

There were even mice living in the machines...had to do some wirng repairs..and almost all axis were locked up rusted..etc etc etc .these machines have been a 2yr on and off project..wasnt easy but.finally are just about done and ready to use.

[sam_sam_sam]

Re: Dc power supply in cnc not working

This is just an recommendation for you I would put a temperature sensor on the heat sink and monitor the temperature while you are using the machine

Do not use an info red temperature sensor to do this to me they are not very accurate for this application

Because I do not think there is not enough cooling going on with this setup but the only way to know for sure is monitor the temperature over a period of time

Did you use thermo sink compound on the heat sink before you install the ic chip to the heat sink and is there a thermal pad on the ic chip to the heat sink

Also monitor the 42 volt power supply while you are using the stepper motors and see how much it verys while running ( my thinking is that the voltage might be spiking and if it is this is going to be a very big issue over time )

[shelby5041]

Re: Dc power supply in cnc not working

Thanks
Yes i always use thermal paste and the L298 chip has an aluminum pad on back of it.

This is just a hobby machine i will only use it once in a great while so im not really going to invest more time on it

It should be fine...before i gotcthem they were used for15- 20years with no issues

[eccerr0r]

Re: Dc power supply in cnc not working

One thing I'd suggest is that you don't idle the machine on with the steppers loaded/locked. At least if the motor is moving, it distributes the heat around.

BTW you're scaring me, wonder when my 3d printer will have its stepper drivers and motors fail...

[sam_sam_sam]

Re: Dc power supply in cnc not working

BTW you're scaring me, wonder when my 3d printer will have its stepper drivers and motors fail...

I had a stepper motor that I had bought that had some type of failure that I could not figure out I did have one stepper motors driver board go bad and just basically shorted out you will know when this happens because it pulls down the power supply

It depends on how the programming was done my 3D printer has run for hours at a time and the stepper motors are room temperature I have checked them many times because of how it does this in short burst and continuously I had the same concern as well

If fact if my work schedule would get easier not having to work 5 days week ( go back 4 days a week ) I would have more time to do some project that would like to do but just do not have the time

[sam_sam_sam]

Re: Dc power supply in cnc not working

One thing I'd s uggest is that you don't idle the machine on with the steppers loaded/locked. At least if the motor is moving, it distributes the heat around.

I would also highly recommend this as well

BTW you're scaring me, wonder when my 3d printer will have its stepper drivers and motors fail...

See my comment above

[sam_sam_sam]

Re: Dc power supply in cnc not working

the stepper drivers on these machines use the L297 and L298 circuit

i have never had to replace the L297 but i have had to replace 2 other L298 on this machine and other machine

here is a link to what l297 and l298 are

https://www.apogeeweb.net/circuitry/...or-driver.html

One thing I would check is that the axis movement is very easy by hand with out power on but do not do this at very fast speed or you can damage the stepper motor controller by doing this procedure because if it does not move very freely it can cause the current drawn by the stepper motors or motor to be excessive and can damage them

Because these stepper motors can produce electricity voltage and current this will damage the ic chip

[eccerr0r]

Re: Dc power supply in cnc not working

The 3d printer's motors do not get warm, fortunately. However as the drivers are embedded in the box I haven't been able to measure temperature on those. Need to make sure the fan stays working...very crappy fans...

[shelby5041]

Re: Dc power supply in cnc not working

Thanks for all the very good info

I see people on utube always moving axis by hand ehich i know is not good for electronics......but oddly enough t my gerber dimension 200 cnc router does not have a z axis jog mode

To set z axis you have to dosable stepper and msnually turn the z axis knob at top....per msnual.

Gerber is a big company....

[shelby5041]

Re: Dc power supply in cnc not working

Most 3d printers are disposable made like crap

I have an old printerbot simple metal...one of the worse designed mschines ever made.

Elect are literally crammed under machine enclosed with no vent holes..no fans.

[shelby5041]

Re: Dc power supply in cnc not working

Hey samsam...i want to elaborate on something you mentioned...i did notice that when i was checking the 42v while troubleshooting...

I was getting about 42.3v consistently however after i replaced the L298 and hooked up the stepper motor cable....i checked voltage output at ps pins and it was 40v...so the 40v is going to all driver boards....now its a fsct driver boards can be run using a wide voltage range like 12vto48v....so i doubt this will affect performsnce just based on voltage...however my concern is why did i lose 2volts coming from ps.

This doesnt seem right

What could cause slight voltage drop....and is this something that i should troubleshoot or leave it be.

[sam_sam_sam]

Re: Dc power supply in cnc not working

Remember that when you put a load on a linear power supply this is normal what you have to be concerned about is when the load turns OFF does your voltage spike higher than 42 voltage then over a period of time this will take a toll on the voltage regulator burning out again it might not be very good for stepper motor ic even though it not to it maximum rating controller chip either

This when you might consider putting a tv diode to clamp the voltage spikes or put some incandescent light so that there voltage is higher than the voltage on your power supply this would put a constant load on the power supply and voltage spikes would be a lot less

By the way what is your line voltage at your outlets or what is the voltage at your electric drier also what is the voltage requirement of this machine that we have been talking about ( 120 or 240 volts )

The reason I ask is because the voltage at my outlet sometimes as high as 127 volts but this is because I live over 250 feet from the road and the electric company that we have service with would not put a transformer closer to my house so what they did was up the voltage coming into the house because before this was done the voltage coming to the outlet would as low as 101 volts when the air conditioning would turn on and some time the compressor would have issues

So on a linear power supply that would normally be a certain voltage in my case the voltage is higher than you normally have some where else in the house down the street

[shelby5041]

Re: Dc power supply in cnc not working

Thanks samsam

Yes i do understsnd regarding load but in my case there was no load on the 42v side

The stepper motors werent even on...cnc controller was off.

Ill monitor voltage next time im in my workshop

[sam_sam_sam]

Re: Dc power supply in cnc not working

If you were to load the 42 volt power supply output even if it 500 milliamperes would help keep the voltage more stable