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  #1  
Old 16th July 2017, 02:24 PM
EveMurph EveMurph is offline
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Default Durst M302 Color Enlarger, Transformer Troubles

Hi,

This is my first post on here, I've recently inherited a Durst M302 Enlarger unfortunately I am unable to check if the enlarger itself is working as the transformer isn't working. I've changed the fuses so that can't be an issue and anything beyond that is out of my capabilities.

I was wondering if anyone could help with what the issue could possibly be or if you have any suggestions of other transformers I could replace it with?

Also I'm looking to get a timer for this enlarger if anyone has any suggestions or technical info for that I'd really appreciate it.

Thank-you!
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  #2  
Old 17th July 2017, 12:32 PM
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Bob Bob is offline
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Hi, and welcome to the forum.

The transformer you have will depend on which type of head you have so a quick digisnap of the unit should help us figure out what possible replacements may fit the job.

First obvious thing to check is the lamp as they are often easily killed in action (or transit).

If all is well there, I would check the continuity of the cable from inside the transformer to the head as it is often mechanical failure in either the cable, switches or connectors that cause electronics equipment to fail - is there any voltage directly at the transformer output and if so, does it reach the lamp? If you don't have, or can't borrow, a meter, determining some of that will be awkward, requiring a known working bulb of suitable voltage and some wire wrapped around it

Also (if not already done so) have a poke around inside the transformer as there may be a fuse hiding inside the unit.

Good luck! Bob.
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  #3  
Old 17th July 2017, 01:18 PM
Chrisvclick Chrisvclick is offline
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If that is a switched mode power supply, it can have very high voltages stored in it for up to a couple of hours after last "energised". Suggest not poking around in it if you do not know what your doing !!..
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  #4  
Old 17th July 2017, 08:34 PM
EdmundH EdmundH is offline
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Before you go any further; don't assume that its the transformer at fault unless you can test it with a voltmeter. More likely that the halogen bulb has blown, it won't necessarily look faulty. It may even be corroded bulb contacts, which should also be cured by replacing the bulb (I had this happen recently.

If it really is the transformer at fault, then there was a very similar thread recently. Although it refers to a different make of enlarger, the transformer requirements will be the same.: http://www.film-and-darkroom-user.or...ht=transformer
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Old 18th July 2017, 05:52 AM
John King John King is offline
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Default Faulty power supply

Quote:
Originally Posted by EdmundH View Post
Before you go any further; don't assume that its the transformer at fault unless you can test it with a voltmeter. More likely that the halogen bulb has blown, it won't necessarily look faulty. It may even be corroded bulb contacts, which should also be cured by replacing the bulb]
Even if the bulb has blown, there are small pilot bulbs that illuminate the colour dials. These should still light up. If they don't, it sounds very much like a power supply problem as you think

If you contact 2nd hand darkroom supplies, they very often have spare transformers for sale which will not be advertised on their website. I replaced the complete colour head for my LPL7700 for a very reasonable price but the head was not advertised.
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Old 19th July 2017, 02:53 PM
jlbruyelle jlbruyelle is offline
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Hi, I have a M301 color which is almost exactly the same as EveMurph's M302 - the biggest difference being the colour of the painting. This colour head never had separate bulbs for the dials, so a blown halogen bulb will also prevent dial illumination. I can also say with certainty that this transformer is a just a transformer (the M301/302 never had a switching power supply) and doesn't even have a built-in fuse (except in the UK plug version), so the most likely culprit is a blown halogen lamp, or possibly an oxidized lamp socket (a common problem on those uncooled enlargers). You can easily do a visual inspection of the lamp's filament to check whether it's broken, or if you have a multimeter you can check the continuity of the filament (its resistance should not exceed a few dozens of ohms at most) and the transformer voltage which should be 12V AC, probably a little more since you are measuring it without a load.

Note that all three parts (bulb, socket and transformer) are pretty standard and can be purchased new.
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Old 19th July 2017, 08:29 PM
namir namir is offline
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I am no expert in concern of electric or electronic issues, I give my best:
I have a M305, afaik it uses the same transformer- the one I have is named EST 305, that is often sold together with the M302 on ebay. And it is broken. The problem (or at least one of the problems) with my transformer is a capacitor exploded (it is easy to find the broken part). I think it can be fixed - but as I am not that used to soldering, I simply bought a cheap 12V 105W halogen-transformer (actually meant for halogen worktop lighting etc.) - changed the cables (did not want to destroy the original cable), it works fine so far.

This kind of replacement is actually really easily done - but if you do anything like that, maybe are not that experienced, keep in mind you are dealing with electricity - mistakes can have real bad consequences (electric shock, fire...) If in doubt, to buy a working second hand EST 305 (or another fitting Durst transformer) would be the better solution. If you don't like to solder around yourself, maybe you can find a professional, to do that for you.
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Old 20th July 2017, 08:20 AM
jlbruyelle jlbruyelle is offline
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The power supplies that came with the M301-302 and the M305 are actually different, but one can certainly use a TRA305 or EST305 on a M302 if memory serves. The TRA305 is a mere transformer, whereas your EST305 is a regulated power supply - more sophisticated, more stable voltage, but prone to aging as you have discovered.
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  #9  
Old 20th July 2017, 11:19 AM
jlbruyelle jlbruyelle is offline
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  #10  
Old 20th July 2017, 04:59 PM
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photomi7ch photomi7ch is offline
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A simple test of the transformer is to plug it in switch it on and listen for a hum then it works. the next check is to find out if the lec is leaving the transformer. You can do that with an embarrassed finger which is a tester that lights up when it detects lec.
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