Enlarger transformer repair Melbourne

Discussion in 'Australia' started by Kevin Caulfield, Feb 6, 2012.

  1. Kevin Caulfield

    Kevin Caulfield Subscriber

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    I recently bought a Durst L1200 colour enlarger. The TRA 450 transformer didn't work at first. It had a 5A fuse instead of a 2.5A fuse. I checked the inside and made sure it was set to 240 V and replaced the fuse with a 2.5 A one. It then worked, at least for a little while but blew the fuse after several on/off cycles. I have since gone through several more fuses in the same manner. These are ceramic fuses which I found at Jaycar.

    Can somebody please suggest a repair place where they would be able to check out the transformer to work out why it keeps blowing fuses?

    Thanks for your help. :smile:
     
  2. polyglot

    polyglot Member

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    Make sure you use a slow-blow fuse. A fast-blow fuse on the primary of a transformer will be destroyed by inrush current, as you've found.

    Edit: you don't need ceramic (sand-filled) fuses for this application, that's total overkill in terms of blocking. They're meant for use with hugely inductive loads and high-power applications, e.g. where the fault-current might be much larger than the operational current. The idea is that the gas in a glass fuse can form a plasma but that sand will not. Edit 2: ceramic fuses are not slow-blow, therefore they *will* fail early.
     
    Last edited by a moderator: Feb 6, 2012
  3. Steve Smith

    Steve Smith Member

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    As Polyglot says, use a slow blow fuse. These are usually marked with a 'T' (for time) so you need one marked 'T2.5A'.


    Steve.
     
  4. Kevin Caulfield

    Kevin Caulfield Subscriber

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    Thanks, guys. I'll try a slow-blow fuse in the next day or two and will report back. :smile:
     
  5. polyglot

    polyglot Member

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    Also easily recognised because they tend to contain a spring-like heatsink instead of just a tiny tiny straight wire.

     
  6. Bob-D659

    Bob-D659 Member

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    There are three versions of that unit, post a pic of the inside and I can probably email you a circuit diagram for it.
     
  7. mick8585

    mick8585 Member

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    I have had a voltage stabiliser(Devere 504) repaired expertly in the Croydon area recently. Very happy with the service. If you want I can let you know the business name.
     
  8. Kevin Caulfield

    Kevin Caulfield Subscriber

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    Thanks for the posts. I bought some slow-blow fuses today and will give them a go later today. They are actually ceramic like the other ones, but this time they are marked "T 2.5A", so they should be fine. I checked the other ones and they were "F" instead of "T".