Hi all. New to the forum, long time lurker. The skinny. I was noticing less power from my lasers. Of course do the obvious. Check for continuity across whole machine. Visually inspected and thouroughly cleaned lasers. Had 1.7ish volts at pwm and ground on laser lead. Checked again at x axis shunt. Checked at main board. With all wires off the main board, i drew a line in light burn. 100% power 600mm/m speed. Check pwm and ground at board. 1.7v. Lowered power to 50%. 300v dc meter jumped between 0 and 1 volts. Took main board out. Visually inspected. When pwm led comes on(when i start that line, only over 50% power) its very dim and shakey. The board is OLM-PRO-V10. Could it be the cap next to pwm out is going bad? Haven’t tested it yet. Any ideas?
PWM is used to turn the laser off/on.
If you want 50% power it lases at 100% for 50% of the time.
Most of these newer machines that are 32 bit use a 3.3V cpu. This should work for a diode laser as a logical high in a 5V system is just over 1/2 the voltage or ~2.5V.
Take the boards voltage and multiply it by the percent power this will give you the value of your voltmeter reading.
In any case, 1.7V is too low to enable a diode to lase, so there is some issue with your board.
@misken is up on these and may be able to be of more help.
Hope I made sense?
I second Jack.
Small addition: since the signal is a PWM signal, you can’t reliably measure it with a dc meter. You need an oscilloscope to really measure it. The signal should be in the 0-5V range, depending on the speed of your DC meter, your values are ok, but you don’t see it.
I agree, however, I know many people don’t have a regular voltmeter. Sometimes you have to use what you have and make do..
Many of the boards today are 3.3V processors. My DCS32 has a voltage translator so it’s output is a 5V ttl compatible signal.
This changes when you use them on a co2. Monport shipped a number of co2 machines what could never reach full power because they did not have a ttl level signal, so it could never reach the full 5V. When we figured out they dumped these on their customers, clearly without any kind of testing.
Any analog meter will read the RMS voltage applied. This could be dependent on your pwm period. I’ve used a period of just below 1mS and up to 50uS and my meter reads exactly what I’d expect…
I have both mechanical and electronic meters, both measure an RMS value of the waveform. There is no way a mechanical meter can follow most of these signal changes and most don’t try. All of my digital meters work as expected within the rage of periods I mentioned.
Although the specifications of these include the ttl range, most switch at ttl levels, as long as the on part of the waveform is at or above the switching value of a high value to ttl is should work. This is why you can get away with a 3.3V pwm signal driving a ttl interface diode module.
I don’t have a voltmeter with either a digital or only analog that doesn’t properly show me the correct RMS value.
I’d suspect it’s a 3.3V processor delivering 3.3V to the diode module.
No matter what he’s using, if he holds a 100% power, it will read whatever the controller is producing.
I think the 1.7V value is not consistent with a working 3.3V pwm. Or at least not enough to turn on a ssl.
If he’s advising that he’s seeing low power, I’d say 1.7V is not enough to even turn on the module at all.
If you know of a regular meter that shows this aberration, I’d like to know, so please advise. I know my co2 lps has a current meter, that is about useless, it jumps all over the place. It’s only useful if you keep constant power on it long enough for it to stabilize. If you do that, it reads the same as my cathode meter. Of course, glass tube co2 are analog devices, but the rms meter will show the same percentage analog or digital.
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