Enlarger transformer repair Melbourne

[Kevin Caulfield]

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.

[polyglot]

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.

[Steve Smith]

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.

[Kevin Caulfield]

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

[polyglot]

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

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.

[Bob-D659]

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

[mick8585]

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.

[Kevin Caulfield]

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".