Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,553   Posts: 1,544,938   Online: 814
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21
  1. #11

    Join Date
    Feb 2008
    Location
    Winnipeg, Canada
    Shooter
    Multi Format
    Posts
    1,301
    Stabilizers, stabilized power supplies and power supplies like the TRA 450 are all different beasts. All depends on what functions your L1200 stabilizer provides. A generic 24 volt transformer is unlikely to deliver 10-15 amps needed for a high wattage bulb.

    Open up the cover and post a pic or three in a new thread and someone may be able to help.

  2. #12
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,219
    Quote Originally Posted by 36cm2 View Post
    Not to hijack the thread, but I believe my Durst L1200 stabiliser was fried last week due to a power surge. Does this mean I can just replace it with a generic 24v transformer, or am I oversimplifying?

    Thanks,
    Leo
    A few different comments here.

    1) does your unit have the EST500?? If so, there is filter capacitor (replacement PME271M622KR30) (to keep spurious signals from bothering other AC equipment on your lines) that has a tendency to fry in those units. Replacing the capacitor should fix it. See "PME 271" in photo below (J. Bannow photo):



    2) A voltage spike big enough to fry the transformer would be quite wild. I'd think you'd have arcing in the wires all through your house if that were the case.

    3) A generic transformer with the same Watt (or VA) rating as the original should work fine to power your bulb. These transformers can be expensive, though.

  3. #13
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,219
    Quote Originally Posted by Marco B View Post
    Is it than because the socket due to repeated heating/cooling cycle, simply no longer makes proper contact, and causes unwanted arcing / charges to jump over to the lamp contacts, resulting in some form of damage?
    I'm not 100% sure (based on the EST450 schematic) how a bad socket can fry the bulb in the original posters case. I have good evidence that in TRIAC based regulated supplies (where a TRIAC is the only thing between an 82V bulb and the 120V mains) oxidation (from arcing) in the socket leads to high resistance, causing the TRIAC to open up to "full on" which increases the voltage up to 120V and a spark will jump from the bad socket contact to the bulb pin and instantly fry the bulb. In this case there will be an identifiable 'weld mark' on the bulbs pin. (Ask me how I know, I fried 3 in a row in about 10 minutes before I figured it out one day). The more this happens, the worse the socket gets, because the arcing leaves non-conductive carbon residue each time it happens.

  4. #14

    Join Date
    Feb 2008
    Location
    Winnipeg, Canada
    Shooter
    Multi Format
    Posts
    1,301
    As a WAG, I'd suspect the socket with the EST 450 or any supply, as if it's arcing badly it will overheat the pin on the bulb and fracture the seal in a few minutes and air will kill the filament.

  5. #15

    Join Date
    Sep 2004
    Location
    Toulouse, France
    Shooter
    Large Format
    Posts
    527
    I forgot to add that I fried a bulb in the TRA450/CLS450 head I own because one of the big wire in the plug at the end of the head cable was unsoldered and made intermittent contact. I think you should have a look at the plug and sockets !

  6. #16
    Marco Gilardetti's Avatar
    Join Date
    Jun 2005
    Location
    Torino, Italy
    Shooter
    Large Format
    Posts
    420
    Thanks for all the insights and suggestions, I appreciate it.

    Quote Originally Posted by ic-racer View Post
    1)None of the TRA450 schematics I am aware of show a stabilization circuit. Basically its just a 24v transformer and some additional 'housekeeping' circuitry.
    That's allright. However, I own a EST 450, which is clearly stabilised, with a big big power transistor mounted on a big big heat sink. It also has a heating simulator made with a power resistor and a heat sensor which turns the head fan on and off automatically. Everything (fan, lamp, timer) is switched by relais. A very sophisticated machine.

    TRA = TRAnsformer
    EST= Electronically STabilised

    The lamp socket is made of first-choice porcelain with heavy-duty contacts and firesafe cables, all in perfect shape and constantly fan-cooled. I would definitely rule it out.

    It must be said that the lamps used in the CLS 450 head have almost nothing to do with those of the households appliances. "Normal" halogen lamps cost one buck or less and are usually made in China. Those for the CLS 450 head are made exclusively in the U.S.A. by General Electric and cost € 30 each, to say one thing. Also, they are "pulled" to the extreme, as Marco B already said. Thus I suppose everything, good and bad things, happen much FASTER than in "normal" halogens. So the symptoms are fully compatible with the theory of insufficient voltage: the glass gets progressively darker and darker because of a grey-matter deposit (Tungsten, most probably), until the filament brakes. The whole cycle takes 3-4 minutes.

    I suppose the voltage comparator or the voltage reference or both are faulty, as the output power transistor look allright and shows no sign of stress. It's hard, however, to draw things out without a schematic.

    The lamps themselves are all right, as the first which broke yesterday had been previously used for many weeks with no issues at all, and the replacement all came from its same batch.

    @ Vorgonyi, thank you very much for that address; I tried to contact Durst Italy (no reply so far) and it case that attempt fails I will try to ask Mr. Mehlmann. Thanks a lot, I appreciate it.
    I know a chap who does excellent portraits. The chap is a camera.
    (Tristan Tzara, 1922)

  7. #17

    Join Date
    Feb 2008
    Location
    Winnipeg, Canada
    Shooter
    Multi Format
    Posts
    1,301
    I have a CLS450 head and the early model TRA450 power supply, the lamp socket has been replaced at least twice, once by me and at least once before I bought it. They do wear out, and from the outside they still look perfect. The bulbs used in the CLS450 are standard projector bulbs and are also made in Mexico and Japan as well. Probably in China too.

    If your EST450 uses a relay to switch power to the bulb, check the contacts in it, they get pitted and burned and cause all sorts of problems.

  8. #18

    Join Date
    Sep 2004
    Location
    Toulouse, France
    Shooter
    Large Format
    Posts
    527
    And triple check the plugs at the end of the head's cable, plugging into the EST450. If one wire is making bad contact, it cause nasty things to the power supply and the bulb...
    Last edited by GeorgesGiralt; 02-08-2011 at 11:56 AM. Click to view previous post history.

  9. #19

    Join Date
    Feb 2008
    Location
    Winnipeg, Canada
    Shooter
    Multi Format
    Posts
    1,301
    Just adding, both your EST450 and the CLS450 were made from 1974 to 1979, so both are at least 30 years old, and Durst stopped support and supplying parts in 1989. Thousands of heat/cool cycles cause items to wear out, including the solder joints as GeorgesGiralt pointed out. When you use a 250 watt bulb that draws 10 amps of current, it is recommended to change the bulb socket for every second bulb you replace. Durst USA have a replacement power supply, it is approx $1,000. The earliest TRA450, the one with a two pin european type socket on the back is the easiest one to keep going. It has the fewest parts and only one high current relay to replace when the contacts on it burn out.

    Link to Durst products and support dates: http://www.durst.it/fileadmin/user_u..._Equipment.pdf

  10. #20
    Marco Gilardetti's Avatar
    Join Date
    Jun 2005
    Location
    Torino, Italy
    Shooter
    Large Format
    Posts
    420
    Don't say it loud but I think I've finally fixed the issue. I have to thank once again fellow Georges Giralt for sending me the EST 450 tech manual complete with schematics, that although written in mixed french/german has been extremely useful in understanding this complicated machine.

    With reference to the schematics, I replaced all electrolytic capacitors C1 C2 C3 and C5. Especially C3, although aesthetically in perfect shape, was totally out of order and was most probably the main cause of the issue.

    Also resistors R42 and R43, which showed traces of burns (extended to the PCB), have been replaced. The power resistor R42 undergoes a very heavy duty and I decided to overrate it at 10W; still it heats up considerably so it was previously underrated in my opinion. R43 was instead probably OK (maybe its traces of burn came up from R42 below) but I replaced it nonetheless while on the job.

    The head fan thermal sensor S3 has also been replaced; although it could not be the cause of the general out of order it behave erratically in the last months and clearly asked for being replaced.

    I tried the enlarger for 3, 5 and then 10 minutes of continuous operation, surveying the light intensity with a lightmeter, and everything seemed all right. Now the final test is needed: a printing session, that I will do as soon as possible.

    As a side note, in case anyone will experience problems in the future: it is normal that the tension output to the lamp reads below 24V, it was done intentionally by Durst to prolong lamp's life. However, the voltage is not a sine wave, so it can be properly measured only at the oscilloscope.

    Also, on the center of the PCB there's a small metallic cube which contains a light sensitive resistor and a micro lamp that simulates the headlamp behaviour. It is important to check that this small lamps is not burned out. It can be tested with a 9V battery by removing the black paint from its back: if in order, its weak light should be visible in transparency.
    Last edited by Marco Gilardetti; 10-10-2011 at 02:56 AM. Click to view previous post history.
    I know a chap who does excellent portraits. The chap is a camera.
    (Tristan Tzara, 1922)

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin