Durst TRA450 problem

[himilsbah]

My Durst 1200 with TRA450 stopped working today after a while I saw the smoke.
After reassembling the trafo I found one burned resistor.
Does anybody know the place where could I get electronic diagram of TRA450?
I consider try to fix it locally and I don't think that will be possible without the diagram.
Any help gratefully received.

Bartosz

 

[ic-racer]

Can you make out any markings on the resistor? Did the fuse blow also?
Check with durst.it, they may be able to supply a wiring diagram.

I recently found a blown resistor on a Durst CLS head and it was easily replaced:

 

[Bob-D659]

Bartosz, if you can post a picture of the inside of your supply showing the burnt part, I'll take the cover off mine and see what the value is, and if there is something else that could go as well.

 

[himilsbah]

Thanks for reply.
The fuse seems to be fine.
Bob, clever idea with that mirroring - see following pictures.
B.

 

[himilsbah]

I've just got the TRA450 diagram from Durst.it (thanks guys).
If someone interested please write me.
B.

 

[ic-racer]

So, in my case the resistor blew when I believe the MOV (metal oxide varistor, or surge protector) shunted to ground in order to protect the relay coil during a surge.

In your case I see a number of things. First, you also are in proximity to a MOV (the black component labled S10K50). So the MOV may have caused to resistor to fail.

Secondly, both the resistor and MOV are not attached by any means that a commerical manufacturer of electrical equipment would use. All connections need to hold before the solder gets applied. Those components look like they were added later as a modification.

Can you e-mail me the schematic, I can have a look.

 

[Steve Smith]

Secondly, both the resistor and MOV are not attached by any means that a commerical manufacturer of electrical equipment would use.

That's what I was thinking. it doesn't look like anything I would want to buy (it does look like something I would make though!).


Steve.

 

[Bob-D659]

There is also a triac hiding under the MOV. Durst modded the unit with a triac to fix problems with the relay contacts burning out. I know the relay in mine was replaced before I acquired it. http://www.pairlist.net/pipermail/largeformat/2005q2/018897.html

 

[himilsbah]

Resistor blew again after replacement.
Regarding the MOV, I saw it's inconsistent with the diagram but the diagram number I have is:YA 01.174.12, on my board is: YA 01.174.11. Schematic also says CLS 450 Color head instead of mine BWL450.
confusing...
Bartosz.

 

[ic-racer]

So, on the schematic the Triac was added around 1977. So, it looks like someone may have upgraded your unit. Perhaps the MOV was added after 1977 but not on any of the schematics that were preserved at Durst.it.

Check that the MOV is not conducting. Triacs can be checked, but may be easier to just replace it.
Check for a short in the color head between pins 1,2,3a and 5a. That is a pretty simple schematic. If the transformer is OK you should be able to get the unit working again.

 

[ic-racer]

Also double check input voltage (220v vs 240v). Did the resistor blow right away, or only after triggering the main colorhead bulb. Does the small bulb La1 light up?

 

[Bob-D659]

Bartosz, thanks for the pdf's, they just printed.

 

[himilsbah]

THE PROBLEM SOLVED

Triac replacing solved the problem. Equivalent for original Triac TAG256/200 (no longer produced???) is Q2015R5.
I haven't found it in my area but seller suggested BT138-600 as equivalent.
So far I'v tested short switching series and long exposition as well and it works fine.

Many thanks for your support
Bartosz

 

[Bob-D659]

Excellent. I was going to suggest replacing it as the only other problem could be the relay in your unit, and that would not burn out the resistor.

Thanks for the diagrams, my power supply is the 3D version, not many electronic components in it. I will have to clean the relay contacts on the replacement one that is in it, and I will look in my parts bin for a 15 or 20 amp unit. The existing 10 amp one is a bit on the small size for switching for a bulb that draws 10 amps when running.

 

[Dave Dawson]

I replaced the relay on my spare psu with a 30A relay!

Cheers Dave