Troubleshooting a K40 Laser Power Subsystem

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Symbol Key

?

N

?

= the NO path in a flow

= a connector to another flow

= A test procedure used in a flow

These symbols are used in this document to designate a functions as described below

Y = a YES path in a flow

Preparation:

Make a safe environment

A

Is the green LED on the LPS illuminated?

Note: some LED’s maybe red.

Y

N

When the beam is or may be present:• Ensure all covers & interlocks are

engaged• Wear your laser eye protection

Turn ON the power to the machine

The LPS is not getting AC power or it has an

internal failure

Proceed to B

Y

N

You said the green LED was not illuminated on the LPS.

That got you here. The correct VAC is present at the LPS therefore something is internally wrong with your

LPS.

The fuse located in the input plugs receptacle could be blown.

Testing the AC Input:

A

I

AC AC from mainsCaution: Read HIGH VOLTAGE with DVM on AC

voltage scale across these pins

Depends on country

(120-220VAC)

AC AC from mains

G Ground With DVM on volts scale read to ground 0vdc

L- Laser cathode return

DO NOT MEASURE.

P or Q

Test

ing

Met

ho

dsUse this table and

test method to test for the correct ACV

Is the proper AC voltage present?

The wiring from the K40 main AC socket to the LPS AC connections

Check:

Power at the wall plug could be wrong or missing.

Shown is US power. Your plugs may be different.

When you push the “Test” button down on the LPS does the laser

fire?

Y

NSomething is wrong

with your LPS.

When you push the “Test Switch” button on the control panel does the laser fire?

At the control panel Engage the “Laser

Switch”

Insure all interlocks are closed

Interlocks may be:• Covers • Water flow switch• Over temp switch

Initial Tests:

B

I

N

Y

Something is wrong with the control panel its wiring, the laser or

the LPS…

Your laser is “MANUALLY”

operating properly. K

Test the programmatic operation of your

machine.

D

Troubleshooting white connector Control Panel’s connection to the LPS

Do the connectors on your LPS look like this?

Y

D

N FGo to

Signal Function Test Procedure Correct Reading

L Laser fire from controller

Touch this pin to ground and the laser will fire if the “LASER SWITCH” is on.

Laser fires

5V 5vdc to controller

With DVM on volts scale read to ground 5vdc

G Ground With DVM on volts scale read to ground 0VDC

24V 24vdc to controller

With DVM on volts scale read to ground 24vdc

5V 5vdc to pot With DVM on volts scale read to ground 5vdc

IN Analog power With DVM on volts scale read to ground. Voltage varies as pot is turned

0-5vdc

G Ground With DVM on volts scale read to ground. 0vdc

G Ground With DVM on volts scale read with to ground 0vdc

P+ “Laser On” With “Laser On” switch “ON” on volts scale with DVM read to ground

Ovdc

Perform the tests in the table below

AC AC from mainsCaution: Read HIGH VOLTAGE with DVM on AC

voltage scale across these pins

Depends on country

(120-220VAC)

AC AC from mains

G Ground With DVM on volts scale read to ground 0vdc

L- Laser cathode return

DO NOT MEASURE.

Co

nn

ecto

rs f

rom

rig

ht

to le

ft

K+ Laser Test Button

Push & Hold “Laser Test” Button & measure with DVM on volts scale to ground.

0vdc

K- Laser Switch With switch “On” reads on volts scale with DVM to ground

0vdc

H

Troubleshooting green connector control panel’s connection to the LPS

Do the connectors on your LPS look like this?

Y

F

N GGo to

Signal Function Test Procedure Correct Reading

L Laser fire from controller

Touch this pin to ground and the laser will fire if the “LASER SWITCH” is on.

Laser fires

5V 5vdc to controller

With DVM on volts scale read to ground 5vdc

G Ground With DVM on volts scale read to ground 0VDC

24V 24vdc to controller

With DVM on volts scale read to ground 24vdc

5V 5vdc to pot With DVM on volts scale read to ground 5vdc

IN Analog power With DVM on volts scale read to ground. Voltage varies as pot is turned

0-5vdc

G Ground With DVM on volts scale read to ground. 0vdc

L Test Switch Push & Hold “Laser Test” Switch & measure with DVM on volts scale to ground.

0vdc

P Laser Switch With switch “On” reads on volts scale with DVM to ground

0vdc

G Ground With DVM on volts scale read with to ground 0vdc

Perform the tests in the table below

AC AC from mainsCaution: Read HIGH VOLTAGE with DVM on AC

voltage scale across these pins

Depends on country

(120-220VAC)

AC AC from mains

G Ground With DVM on volts scale read to ground 0vdc

L- Laser cathode return

DO NOT MEASURE.

Co

nn

ecto

rs f

rom

rig

ht

to le

ft

HProceed to

After you measure you LPS inputs

Signal Function Further Checks Go to

L Laser fire from controller

If this test fails and the laser does not fire while running a job the problem is likely the controllers output

K

5V 5vdc Any time 5V is incorrect your LPS is not operating correctly

Go to test procedure N

G Ground Any time ground is not 0V its likely there is a ground connection missing

Check wiring

24V 24vdc If 24V is not correct its likely from a fault in the supply.

Go to test procedure O

IN Analog power If the voltage is not changing with pot position check the wiring and/or test/replace the pot

L

L Test Switch Check the wiring and test the switch M

P Laser Switch Check the wiring and test the switch M

AC AC from mainsCheck the input power and the main fuse located in

the plugs housingI

AC AC from mains

L- Laser cathode return

DO NOT MEASURE.

H

If one or more of the voltages are incorrect, the table below provides more things to try. The tables below are

organized by function.

In all cases trace and verify the wiring and all connections back to the source of the “FUNCTION”.

N

O

P Q

Test

ing

Met

ho

ds

RIf voltages are OK and problem not fixed, try? I

Troubleshooting Your LPS:

I

If you have landed here itspossible that your LPS is

bad (:.Here are some additional

checks

On the left side of the LPS, verify that you have this

switch in the correct position for the mains

voltage you are using… If not set it correctly

• Turnoff the machine• Unplug the machine• Unplug the leftmost

connector on the LPS.

Generally speaking the LPS is not a repairable item but here are some

addition checks to be sure it should be replaced. Check each of these and

correct them if they are incorrect. Then retest to see if the supply

works.

Remove the LPS cover

On the PCB check this fuse to see if it is blown by

using me procedure (N).

N

You can replace the fuse but most likely it will blow

again. If it blows again your supply has a serious internal problem & likely

needs replacement

S

Troubleshooting Your Controllers Output

K

Troubleshooting your controllers interface to the LPS is complex and may require advanced equipment.

Until we have created simple tests you can get help at the K40 forum. But in the meantime here are some

additional things to check.

R

• The L signal is not wired correctly from the controller• The controller is not configured properly for the port being used for PWM (L)• The controllers PWM configuration is not correct• The Laser module in the configuration is not enabled.• The job is not sending anything to the controller• The S value is 0 in the gcode.

R

Testing the pot & switches

L

This is the part you are testing

TURN OFF POWER

Use this scale

Disconnect the POT from its circuit by unplugging it from

the LPS.With the meter as shown to the right. Turn the pot fully in both directions and the resistance (ohms) should change from 0 to max. On some pots the max is 1000

others it is 5000.

M

These are the parts you are testing.

TURN OFF POWER

Use this scaleDisconnect the

switch/pushbutton by unplugging the harness

from the LPS.With the meter connected across the switches pins.

Verify that when the switch or button is activated the

meter reads 0 ohms.

If you have this panel go to:

C

Testing the Digital Panel

C

Caution: This procedure must be

done with the power on.

If you have this kind of LPS connect meter like

this…

Use this scale

At the control panel change the digital

values with the 4 digit controls

If you have this kind of LPS connect the meter

like this…

Caution: This procedure must be

done with the power on.

As the digits areincreased/decreased

the voltage on the meter should change in the range of 0-5vdc

IN

GND

INGND

R

If the correct voltage is not present or does

not change try :

Check the wiring continuity between the panel and the IN pin of the LPS.

Replace the Digital Panel

More Info:

Testing the Internal Fuse

N

This is the part you are testing.

TURN OFF POWER

Disconnect the AC connector

Use this scale

Measure the resistance across the

fuse. If it's not 0 ohms then the fuse is blown.

Dangling endpoints

GYou got here because your LPS is not a type supported by this

document

https://plus.google.com/communities/118113483589382049502?np=wawcHeygmezUmb6FHbqhGenNGNwUHN

iZmdtJGcqF2amV2dzEje

More help can be found here:

https://donsthings.blogspot.com/

RYou got here because you

need more help.

S

You got here because you have an internal problem with your LPS. You can buy a new one or

try a repair.

Rrepairing-k40-lps

Testing MethodsNote: your DVM may not be the same as the one depicted in these drawings. Adapt this content to your particular DVM scale, connections and operation.

Using a DVM to Measure 0-5VDC

Connect to ground Connect to the pin expecting 0-5vdc

Use this scale

N

Using a DVM to Measure 0-24VDC

Connect to ground

Connect to the pin expecting 0-24vdc

Use this scale

O

Using a DVM to Measure 120 VAC

Connect one side of the AC expecting 120vac

Connect to the other side of AC expecting 120vac

Use this scale

P

Using a DVM to Measure 220 VAC

Connect one side of the AC expecting 240VAC

Connect to the other side of AC expecting 240VAC

Use this scale

Q