Page 3 of 9 FirstFirst 1234567 ... LastLast
Results 21 to 30 of 82

Thread: DHOM 532nm TEC setup appears to be totally Kaput!

  1. #21
    Join Date
    Aug 2010
    Location
    London or Spain depending on the weather
    Posts
    1,381

    Default

    Update:

    Managed to insert file using XP .....so here it is


    Click image for larger version. 

Name:	DHOMtest1.jpg 
Views:	38 
Size:	78.3 KB 
ID:	25907

    I also have more logs which I will post later using different ambient temperatures with the help of an air conditioner. This is just the clearest one I made the first day once I had the test rig set up.

    However my latest idea to try a 110vac input will have to wait since all my trafos are a hundred kilometers away in Barcelona and I am up to my ears in work in a village up the coast on the Costa Brava right now.

    Cheers

  2. #22
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default

    Quote Originally Posted by catalanjo View Post
    Update:

    Managed to insert file using XP .....so here it is


    Click image for larger version. 

Name:	DHOMtest1.jpg 
Views:	38 
Size:	78.3 KB 
ID:	25907
    That looks pretty normal to me.... Unless it's just completely shutting off on it's own at the end of the graph there....

    Another question would be, is the power supply providing enough current to the laser driver? It could be that you are reaching the maximum rated current output of the power supply as the TEC's require more as the head warms up.

  3. #23
    Join Date
    Oct 2006
    Location
    Central Florida
    Posts
    7,067

    Lightbulb

    I agree that looks normal to me also; it is a 1 watt laser that produces 2 watts for a few seconds then drops to around 1.5 watts... I assume you powered it down after 2 minutes? I would be worried if it dropped to a half watt after the 2 watt jump; 1.5 watts from a 1 watt laser is more than acceptable. What happens after 10 minutes?

  4. #24
    Join Date
    Aug 2010
    Location
    London or Spain depending on the weather
    Posts
    1,381

    Default

    Quote Originally Posted by 300EVIL View Post
    That looks pretty normal to me.... Unless it's just completely shutting off on it's own at the end of the graph there....

    Another question would be, is the power supply providing enough current to the laser driver? It could be that you are reaching the maximum rated current output of the power supply as the TEC's require more as the head warms up.
    Yup laser is shutting down all by itself (no warning led on this occasion since mod input voltage was 4.5vdc (battery), when I went up to 4.9vdc (bench supply confirmed with Fluke) the warning "Alarm" led came on within one minute so all other logged tests were done at 4.5v. Most of these tests showed the laser settling to an output of about 500mw for extended periods (ten minutes or more) before shutting down completely.


    current to laser driver = aha! that is the question !

    but I still do not know the pin outs of the umbilical between the PSU and the laser so I don't know which points to monitor. No info has arrived as yet from either Shaun or Marc and I can not proceed easily and safely without this info since tracing the wiring would mean opening the head (voiding possible warranty) ....... unless you can suggest some more ideas to try! (non destructive naturally)

    I suppose these DHOM PSUs are fairly recent on the market so no one has taken them apart yet.
    Thanks for your interest Adam. All this would be a piece of cake if someone could give me a guided tour of the DHOM PSU in question.
    My self confidence in electronics doesn't stretch to voiding a warranty by sticking my foot in it whilst measuring voltages and currents, although reason tells me this shouldn't affect anything at all due to the extremely high impedance of the meter when measuring voltages and the extremely low one when measuring current.
    My warranty paranoia stops me short of just clipping the test leads on to all the combinations available.
    I do also have a non contact clamp meter for DC current but it is not very sensitive and the PSU internal leads aren't long enough to wrap a few turns round the its jaws.

    Do you think my Fluke could cause any damage in its DC voltage setting if I pick the wrong leads ?

    All suggestions gratefully accepted... curiosity is gradually replacing desperation fortunately !

    One of the things which pisses me off about warranty returns is that you never get to find out what was going on and what went wrong (let alone why), they just fix it (hopefully) and send it back with no explanation whatsoever.

    I did try your preheating idea and the laser turns off much faster if I go up to local ambient temp of 35C and much slower if I go down to 18C This would tend to confirm the failing TEC diagnostic.

    I will post further test results at different ambient temps once I get back to XP (in linux right now) and I can't seem to upload files to PL. (They all show much the same story however).

    Strangely for a DPSS, even when at fairly chilly ambient temp the immediate startup power output is pretty high.

    Cheers

  5. #25
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default

    Okay, Is the power supply and laser driver located in one enclosure? If it's a lab style, it would plug into the wall. Or is there a separate power supply and driver like in this pic?


  6. #26
    Join Date
    Aug 2010
    Location
    London or Spain depending on the weather
    Posts
    1,381

    Default

    Quote Originally Posted by 300EVIL View Post
    Okay, Is the power supply and laser driver located in one enclosure? If it's a lab style, it would plug into the wall. Or is there a separate power supply and driver like in this pic?
    No it is Lab style all in one unit!

    Cheers

  7. #27
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default

    Quote Originally Posted by catalanjo View Post
    No it is Lab style all in one unit!

    Cheers
    Ouch! Well, that puts a lot of additional testing to a screeching halt. Yeah, you could probably probe around on the connector but, like you said, kinda not worth the trouble if you can't open it up without voiding the warranty. I'd say you have no choice but to return it. The only other thing that may be worth looking into is your modulation input and make sure the umbilical has a sturdy connection.

  8. #28
    Join Date
    Aug 2010
    Location
    London or Spain depending on the weather
    Posts
    1,381

    Default

    Have already opened PSU to check for commutator before plugging in to 220vac but no seals broken!

  9. #29
    Join Date
    Jun 2007
    Location
    Lake Geneva, WI.
    Posts
    2,704

    Default

    Quote Originally Posted by catalanjo View Post
    Have already opened PSU to check for commutator before plugging in to 220vac but no seals broken!
    If the PSU is a separate board from the driver board, did you check the PSU output voltage? I have no Experiance with DHOM lasers but I know a tenth of a volt makes a big difference on LW lasers performance.

  10. #30
    Join Date
    Aug 2010
    Location
    London or Spain depending on the weather
    Posts
    1,381

    Default

    Quote Originally Posted by 300EVIL View Post
    If the PSU is a separate board from the driver board, did you check the PSU output voltage? I have no Experiance with DHOM lasers but I know a tenth of a volt makes a big difference on LW lasers performance.
    Eight leads joining PSU board to driver board 4 grey and four red .

    Will check these voltages to see if they change when I get a chance to input 110vac instead of 220vac.

    My bed beckons.... thanks for input Adam !

    Cheers
    Last edited by catalanjo; 07-10-2011 at 19:23. Reason: 110vac mains alternative

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •