HI,
I was previously running with GRBL and got full laser power at 5V and I recently shifted to smoothie but the power was kinda lower the before. So yesterday I checked the voltage between IN and GND and noticed a 3.6 V instead of 5V for S1 command. after a lot of checking I found that if I disconnect WP from ground I will get 4.98V at IN and voltage reduce to 3.6V when WP connected to GND. I"m sending PWM and active low signal through a bi-directional TTL , and tried to power the HV side(5V side) of LLC from seperate power supply, but result was same. Anyone have any idea what causing it??
Anybody checked there PWM volatge at IN terminal??
I’m attaching my connection diagram.
Thanks
Please, specify your PSU model, it seem to be 3 differents one (at least, not including the very old one), creating different combinations. Connection would depend on PSU. thank you for sharing your experience.
I personally would like to keep the pot as ceiling to protect the tube life. 15ma -> is about 3.6V (from memory) more than 3.3V this is why I use a level shifter.
@StephaneBUISSON http://www.laserpsu.com/laser-power-supply-p-767.html
Mine was eorking fine with GRBL and I didn’t use LLC there, ANd with smoothie If I directly connect smoothie PWM pin to IN(without LLC) i get 3.3 V for S1 command
@Jean-Baptiste_Passan I think we have the same PSU from our previous discussion https://plus.google.com/114978037514571097180/posts/MxAWWe4jmzS
Can you check your pwm voltage
yes my understanding is PWM is a square signal 0-5V in our case with level shifter, it’s the pot to reduce it to 3.6V ceiling.
it’s the frequency (% of time on which vary the laser power)
I just request http://www.jnmydy.com/ for a download link in english for their PSU. (most of the K40)
+Peter van der Walt If remove WP from GND
I’ll get 5V at IN terminal for S1 command(3.3 V smoothie)
Test 1
WP --> GND
PWM from LLC measured with multimeter(PWM is not connected to IN)
S0 ------ 0V
S0.5 ----- 2.37V
S1 ----- 4.90V
Test 2
WP -> GND
PWM is connected to IN and mutimeter
S0 ------ 0.04V
S0.25 ------ 0.91V
S0.5 ------ 1.80V
S1 ------- 3.7V
Test 3
WP—> disconnected from GND
PWM is connected to IN and multimeter
S0 ------ 0.04V
S0.25 ------- 1V
S0.5 ------ 2.12V
S1 ------- 4.85V
@StephaneBUISSON +Peter van der Walt
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If i directly conncet PWM pin (without LLC, ) to IN with WP connected to ground , thers’s no reduction in voltage .I get 3.3 V for S1
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If I use LLC and measure voltage across Output of LLC and GND(PWm is not connected to IN, i.e., IN is open, WP is connected), get 4.9V on multimeter for S1
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If use LLc and connect LLC output to IN and WP to GND, it’d be 3.7 V for S1, that’s the issue. Could it be a LLC issue?
@Athul_S_Nair ground loop ? so no power for LLC, maybe try to power LLC from another 5v source.
@StephaneBUISSON “ground loop” what did you mean?
I tried powering HV side of LLC from a DC supply, but same result . Here also if I disconnect WP voltage will raise to 5V.
Can anyone give me links of laser PSUs having same control like me?
Also what’s the max current can be given by the 5V pin?mine is 20ma, isn’t enough?
What I don’t understand is that if I directly connect smoothie laser pin to IN without any LLC , I get 3.3 V at IN, no reduction in voltage. Problem occurs when connect via LLC.
Could it be an LLC issue?
Can you tell me the MOSFET name in your LLC?
when you have voltage back from the ground, you are not at 0 anymore so the 5V-G isn’t 5V,
you think G=0 but not anymore leading your logic to be mistaken. ground is a problem in this machine. said in a different way your ground leak some voltage.
+Peter van der Walt can you give the link, I could only find one directional LLC in spark fun,
@StephaneBUISSON any way to solve that?
it’s ennoying to solve, try another power source (old phone charger on main, not connected to K40 PSU) at least for confirmation
@StephaneBUISSON when I power LLC 5V side from separate power supply, I will have to connect all grounds together , i.e., GNDs from smoothie , laser PSU, and external DC supply, right?
just power the LLC from other PSU
(the 5V and 0 wire), the 0 and K40 ground ( are from different PSU with no connexion). so you have 5V differencial for LLC (with no ground loop). I would also try to power Smoothieboard with clean 5V, same side as LLC and connect only the PWM
@StephaneBUISSON I’m confused , in LLC grounds are made common, so even if I connect 5v and gnd from external supply , it’ll get connected to gnd from smoothie .
Can you give me a connection diagram ?
a simple paper sketch would be enough
I am not next to my machine, but from http://smoothieware.org/blue-box-guide schema
power the smoothie independently of K40 psu. blue/ orange (orange being 0V not ground).
on the level shifter you have 2 wires (3.3v and PWM 2.5)
on LLC 5V side, 3 wires 0 and 5V from mobile PSU then PWM to in via pot.(for your PSU not my case) don’t forgot 5v (mobile charger to pot). so the pot is PWM 0V (mobile charger) at one end, 5V(mobile charger) at the other end, connected to PSU IN in the middle.
because you have a differential of 5V, (from mobile charger) your level shifter will raise it by 5V (and not 3.6 because 0V and ground are not connected to level shifter in)before being reduce by the pot to the desired value.
level shifter and smoothie could have the same PSU (but not the k40 one, mobile charger is not grounded)
@StephaneBUISSON my laser psu doesn’t have a 24V port so I’m powering my smoothie from a separate SMPS(12V).
On 3.3V side of LLC , 3.3v and GND is taken from smoothie board, and on 5V side , 5V and GND taken from laser PSU. In LLC. Both grounds are made common I.e., GNDs of smoothie and laser PSU are connected together .
In your connection also I’m pretty sure that GNDs of both 5V side and 24 V of your laser PSU are common and you power smoothie from that 24 and LLC from that 5 V, that means all GNDs connected together.
Now say if I power 5 V side of LLC from separate adapter, and 3.3 V side same as before (from smoothie), so GNDs of adapter and smoothie are made common. Now I need to connect GND of smoothie with laser PSU. Simply all ground are connected together.
Also I don’t have any pot in my IN terminal only PWM from smoothie
