Durst 138S psu problem?

[Dave Dawson]

Hi All, I have rescently got a Durst 138S enlarger complete with two mains power supplies. One working the other not (as a spare for repair) The prvious owner told me that the psu's quite often gave trouble and need to be repaired. I haven't investigated any further than checking the fuse in the back of the unit.

a) Is there a 'stock fault' with these units?

b) Does anyone have a cctt diagram please?

Thanks Dave

[Drew Wiley]

138S is the model of the chassis. There will be a separate model number for the lamphouse itself, which you will need to specify.

[Dave Dawson]

The PSU is a TRA301 to supply a CLS301 head.

Cheers Dave

[Donald Miller]

I may be wrong (often am) but the head that you mention is not often mention in the 138S enlarger. Those Dursts that I have owned have all been conventional incandescent condensor lamp houses.

That being said, the CLS301 is a closed loop system light source and the PSU you mention is the power supply to the CLS301 head. The power supply is subject to the common sources of failure of power supplies as a group. That being degradation of the windings through heat deteriorating the insulation or destruction of any voltage regulating circuits/devices due to transient voltages or overloads. Additionally, you could experience failure of electrical connections at any of the connecting points and also if you experienced an overload, beyond design parameters, you might cause either a failure of a safety fuse if so designed and equipped or even a failure of the transformative/regulating circuitry. Such overloads would most likely occur due to a short of load voltage to ground.

The CLS head being closed loop will have a feedback circuit and that is the reason that you have two wire pigtails as you have mentioned.

I hope that this is some help. Perhaps someone who owns one of these light sources can chime in with their own experiences.

Best regards,
Donald Miller

[Dave Dawson]

Thanks for that Donald....As I said I haven't even had the lid off yet but when I do I will check the primary and secondary side of the transformer...The head runs at 120v whilst the feed to the timer and fan are 220v.

Cheers Dave

[Don Wilkes]

Dave: I also have a TRA301/CLS301, and I may have a manual with electrical diagrams. If I don't get back to you within a day or so, poke me with an email: don.wilkes [insert obligatory at-sign] gov.bc.ca

Cheers,
\donw

[Drew Wiley]

The power supply might be difficult to repair. You could replace it with a generic one
but it wouldn't be cheap. Last time I rebuilt one of these CLS301 colorheads I totally
bypassed the power supply and simply replaced the bulbs and sockets for straight
220 line voltage, which tested, actually had less fluctuation than typical stabilized
voltage. I don't know what voltages you have available there. These colorheads can
also be rebuilt to accept modern halogen bulbs, saving you a LOT of money if you
ever have to have the reflectors recoated, which is inevitable, since these are very
hot colorheads. Unfortunately, the only person who currently offers these kinds of
alterations commercially is almost certainly going to cheat you. If you do attempt to
work inside the colorhead itself, be aware that the heat absorbing plates behind the
reflectors are real asbestos. Might be a good idea to replace them with a mineral
board substitute.

[Don Wilkes]

Dave: I did check in my stash of manuals last night, but unfortunately I do not have one for the TRA301, just the manual for the 138S itself. Good luck in tracking something down.

[Dave Dawson]

Dave: I did check in my stash of manuals last night, but unfortunately I do not have one for the TRA301, just the manual for the 138S itself. Good luck in tracking something down.


Ok thanks for looking...Anyone else help please?


Cheers Dave

[ic-racer]

I have 4 enlargers and have had to fix or rebuild the power supply on all 4. For the closed-loop enlargers, I wouldn't have attempted it without the service manual. For my Durst (not TRA301 :( ), I got the service manual with about 5 schematics from Durst.it (it wasn't listed on the website).

[Dave Dawson]

I have 4 enlargers and have had to fix or rebuild the power supply on all 4. For the closed-loop enlargers, I wouldn't have attempted it without the service manual. For my Durst (not TRA301 :( ), I got the service manual with about 5 schematics from Durst.it (it wasn't listed on the website).

Was the problem the same on all 4 power supplies?

Cheers Dave

[Don Wilkes]

Dave: Ic-Racer suggestion about Durst Italy [http://www.durst.it/] is a good one; they've been very nice about helping me in the past. Also see Northern Photo in England [http://www.northernphoto.co.uk/durst.php3] who say, "We can supply instructions and technical information for the complete range of old and new Durst items. "

Also, have you contacted info@durstus.com?

Cheers,
\donw

[Dave Dawson]

Thanks I have sent northernphoto an email.
Cheers Dave

[Dave Dawson]

Problem found......The static contact in the relay is completely burnt away so I've ordred a 30A relay.

Cheers Dave