Coherent Model 200 LPM - Help Reading {Pic Heavy}

[Javalin]

Hey Pman, Don't sweat it. And certainly don't let my LPM keep you up I figured that once I wasn't getting any readings on mA then I should try mV.

This isn't my first meter but it will be the first time I'm measuring anything in the mV and mA ranges. I can't believe I cut off the bottom of the meter in the last pictures. It was in the far right V/R/Hz plug. I ran continuity on the meter but not resistance... being a previously loved meter I guess that should have been the first thing. I haven't tried measuring V while the leads were plugged into the A (left side) so I'm not sure if it beeps or not. So if my DMM gives me 10mW resolution and if the head is reading everything correctly, then I need to figure out why I'm only getting a few 10's of mW from my 520. And the 532 5V modules I got from fasttech are only reading max 50mW :thinking:

~Encap, I did contact them. They got me a manual that gave me a wiring schematic and what the meter was capable of reading but it didn't say much else. Coherent doesn't service or support these older meters but they offered me 25% off a new one if I send in this old one. Not a bad deal but I can't afford a new meter even at 25% off and I kind of like this one... unless it's not reading accurately

Thanks for all the help everyone!

 

[Pman]

Don't worry about it, can't help it. I am VERY conscientious about things and felt like a total idiot. I even took it one step further and mentioned to Arg that you were having trouble and maybe the fuse was blown for the AMP in the meter so I actually said it more than once. Just can't believe I said any of that.
Well, the continuity test should still give the reading so no worries there. It's more of a safety thing. I measure things from low DC to >480V AC all the time. It's a good habit regardless of what you are measuring.

You were supposed to say "you're right, I had the probe in the wrong position" Crud.

Are the Fattech modules pot adjusted or just as they came? If they haven't been adjusted yet then that's not any surprise for output but either way they ALL shouldn't be reading the same. Never seen anything like that with these. They are all over the place. Not sure how they are adjusted to begin with since the mA draw on them are all over too.

I find it VERY doubtful that the multimeter is reading incorrectly. Have any alligator clips you can attach between the jack and the probes?
If I say anything that sounds demeaning because you already know it don't take it that way. Just trying to think of something here.

How old is that meter? Display looks sharp. If it ever starts to fade out there's an easy fix using just 91% Isopropyl alcohol (something EVERYONE should have and it's VERY inexpensive for big bottles).
Speaking of which (yeah, I realize this is off the track) but nail poish remover is a must have too. IT will clean a lot of things that the alcohol won't. OOH OOh, canned air too and some very light machine oil.
While I am at it I may as well throw in that nail polish makes great paint and already comes with a brush and hardens really fast. It's kind of like using automotive paint but MUCH less expensive. The variety of colors is amazing and they only cost a couple bucks each. Always have clear on hand to coat stuff you may want to protect. Unless someone knows why you shouldn't use it that I don't know of. I believe super glue drying will mess up a plastic lens (it's what I have heard) but I've never had an issue using the clear nail polish. 5 minute clear epoxy is great stuff. Have plenty of it around and more than one in case something happens and one gets ruined.
Sorry about that. Just great stuff that popped in my head that had to come out Hope you don't mind. Did I mention razor blades and toothpicks and small brushes? Lol

Maybe you have to sing into the sensor? Reminds me of an old disc jockey mic. Just trying to get you to crack a smile. It really is a great looking piece. Much better looking than my Ophir. Very classy. I know it may sound weird but if I owned it and something went wrong with it I wouldn't sell it but set the whole thing out for display. Eye candy to me. I call dibs in case you feel the need to get rid of it I'll even let you throw in the cat

Pete

 

[Javalin]

Don't worry about it, can't help it. I am VERY conscientious about things and felt like a total idiot. I even took it one step further and mentioned to Arg that you were having trouble and maybe the fuse was blown for the AMP in the meter so I actually said it more than once. Just can't believe I said any of that.
Well, the continuity test should still give the reading so no worries there. It's more of a safety thing. I measure things from low DC to >480V AC all the time. It's a good habit regardless of what you are measuring.

You were supposed to say "you're right, I had the probe in the wrong position" Crud.

Are the Fattech modules pot adjusted or just as they came? If they haven't been adjusted yet then that's not any surprise for output but either way they ALL shouldn't be reading the same. Never seen anything like that with these. They are all over the place. Not sure how they are adjusted to begin with since the mA draw on them are all over too.

I find it VERY doubtful that the multimeter is reading incorrectly. Have any alligator clips you can attach between the jack and the probes?
If I say anything that sounds demeaning because you already know it don't take it that way. Just trying to think of something here.

How old is that meter? Display looks sharp. If it ever starts to fade out there's an easy fix using just 91% Isopropyl alcohol (something EVERYONE should have and it's VERY inexpensive for big bottles).
Speaking of which (yeah, I realize this is off the track) but nail poish remover is a must have too. IT will clean a lot of things that the alcohol won't. OOH OOh, canned air too and some very light machine oil.
While I am at it I may as well throw in that nail polish makes great paint and already comes with a brush and hardens really fast. It's kind of like using automotive paint but MUCH less expensive. The variety of colors is amazing and they only cost a couple bucks each. Always have clear on hand to coat stuff you may want to protect. Unless someone knows why you shouldn't use it that I don't know of. I believe super glue drying will mess up a plastic lens (it's what I have heard) but I've never had an issue using the clear nail polish. 5 minute clear epoxy is great stuff. Have plenty of it around and more than one in case something happens and one gets ruined.
Sorry about that. Just great stuff that popped in my head that had to come out Hope you don't mind. Did I mention razor blades and toothpicks and small brushes? Lol

Maybe you have to sing into the sensor? Reminds me of an old disc jockey mic. Just trying to get you to crack a smile. It really is a great looking piece. Much better looking than my Ophir. Very classy. I know it may sound weird but if I owned it and something went wrong with it I wouldn't sell it but set the whole thing out for display. Eye candy to me. I call dibs in case you feel the need to get rid of it I'll even let you throw in the cat

Pete

My message didn't submit let's try this again

I know, I read that line suggesting I was measuring incorrectly and breathed a sigh of relief. But no, I had it hooked up to the V. The age of the meter, I'm not too sure but snap-on still sells this model on their site so it can't be too old. The dial snaps very crisp and the display is very clear. It is used but I got it for a fraction of the price of a new one.

I don't have any alligator clips. I was hoping to find some around town because I really don't want to spend more on shipping than on the clips. I don't use too much canned air, I have a $200 electronics vacuum in California... or at least I did. someone broke in... so we will see what's left when I get back. And I need some machining oil for dremeling heatsinks I used vegetable oil worked okay for me. As for paint, I have an airbrush that I like to spray with but it isn't always practical for small projects because set up, clean up, and tear down can take twice as long as spraying!

Haha, I don't think I'll ever be getting rid of this one but I will certainly keep you at the top of the list. And you don't have a choice the cat comes with the box. Since I got the meter she hasn't spent a night outside of that box... just haven't had the heart to take it from her. It's a luxury memory foam kitty bed now.

EDIT: The fasttech modules I got are all modded now. I kept one stock as a control group but it last night it had HORRIBLE mode hopping issues so I turned it down a tiny tiny but so now it will run for a minute or so without mode hopping. I have one that the dot is nearly imperceptible. I turned it down to give to my son, it doesn't even measure 10mW on the meter but until I can verify that it is reading accurately I don't want to put it in his host. As far as the readings from the rest I don't have a single one ... that I can remember that hits over 100mW even adjusted up!

 

[Javalin]

Okay just when I though I had it figured out I pulled out an 808 diode salvaged from an ebay green pen...

On the Coherent meter I get nearly 1W or IR! On the DMM I'm getting 300mW :wtf:

The 473 peaked at 100mW on both meters tonight but then started mode hopping which I think is what was causing my super low readings

My 520 reads the same on both at 30mW but I'm getting a reading of ~250mA at the "tail cap" which should net at leat 50-60mW right?

So here I was ready to write this all off on me just having crappy luck with diodes when I had the 808 read 3 times higher on the Coherent meter. Any ideas on that?

 

[ARG]

Not all meters are 1V/1W

It may have a different calibration ratio.

 

[Encap]

assuming the meter is working correctly perhaps the sensor is malfunctioning or needs calibration--not sure what they charge but these guys could do it for you:
COHERENT Calibration Service & Repair | from Micro Precision Calibration.

 

[pschlosser]

My 520 reads the same on both at 30mW but I'm getting a reading of ~250mA at the "tail cap" which should net at leat 50-60mW right?

Remember, most gas lasers lose efficiency over their lifetimes. As a result, lasers are metered by what they output, not how much current they consume. This is, of course, ass-backwards compared to just about any other kind of electrical device.

For this reason, man invented the LPM.

So here I was ready to write this all off on me just having crappy luck with diodes when I had the 808 read 3 times higher on the Coherent meter. Any ideas on that?

Have you confirmed the wavelengths of light this meter will accurately measure? I wonder if 808nm is beyond the range it's designed for, and thus, gives you inaccurate readings.

 

[Javalin]

Remember, most gas lasers lose efficiency over their lifetimes. As a result, lasers are metered by what they output, not how much current they consume. This is, of course, ass-backwards compared to just about any other kind of electrical device.

For this reason, man invented the LPM.



Have you confirmed the wavelengths of light this meter will accurately measure? I wonder if 808nm is beyond the range it's designed for, and thus, gives you inaccurate readings.

The PL520 isn't a gas laser and it's only about a month old.

Supposedly it read CO2 (IR) and a pulsed 607 accurately prior to me getting it. No shorter WL's were measured though, but the blues seem to be reading accurately. The 808 diode doesn't seem logical to be 900mW as the 532 conversion gives about 1/3 (ideally give or take) the output of the pump diode, since the diode was from a cheap ebay pen I'm assuming even less than that but to get ~50mW for green from 900mW or IR you would be seeing 1/18 as opposed to the 300mW that my DMM is giving me which is about 1/6. It also doesn't really make sense that they would put a 1W diode in the pens.

I measured the IR diode raw output with no lens, but I eliminated as many variables between the two meters as I could so if the measurement was off it should have been off for both :thinking:

I think I'm just going to have to get a few lasers that are measured and confirmed by other LPF members then cross check those numbers with what readings I get. I was just hoping almost that it was reading IR low which would explain why my DPSS lasers weren't hitting the expected numbers.