Originally Posted by: TGB 
Cookie -- I have also run into the issue of the power supply cord to a vintage 280 transformer being totally deteriorated. It looked exactly like the pictures you posted. I have replaced it with another cord that I removed from a burned out hair dryer. I'm including a picture to show where I soldered the wires to the transformer. The problem is that now nothing works. I checked for continuity from the solder joints to the plug and that checks out good. But there is apprently no power getting through to the transformer. Any suggestions? What is the devise called that the power cord attaces to? It looks to be some sort of circuit breaker that trips when their is a short on track layout. Is the picture clear enough to determine if there is a problem with this circuit breaker? To me, it looks to be exactly like your photos.
Tolar
Hi Tolar,
At the risk of inciting the wrath of other members who may feel I am encouraging risky activity...., (moderators, if you are concerned, feel free to delete and I will take it off-forum)
BUT, before going any further I absolutely MUST point out the obvious dangers involved here. It is relatively easy (from a practical viewpoint) to replace the mains-lead and your soldering looks to be ok. But I would also have to assume that anyone tackling the replacement of the mains-lead already understood electrical and transformer theory sufficiently well that they were not only confident in replacing the cord itself, but also able to troubleshoot any problems to begin with.
Please believe I intend no disrepect to you or your skills, but the fact you are asking the question just makes me a little nervous about whether you need to be inside your Transformer to begin with because they are not particularly complex - indeed electrically they are more simple than the wiring within some of the Loco's and even the automated analogue control circuits for signals etc.
But, it would be foolish of me to say I have not made absolutely laughable errors in my professional life and overlooked the completely obvious (to everyone else). I'm embarassed to say that on occasion during my tenure with IBM I received the coveted 'butchers-apron' more than once for a repair blunder that I should have known better about.
I am also mindful that on this forum there are some members for whom access to the kind of repair service suggested is simply impractical, and that those same members may well be masters of invention, simply through necessity and have probably undertaken maintenance far more challenging than what we are talking here.
Aside from that, some countries have more or less stringent laws around this area than others. If the region in which you live allows private individuals to undertake maintenance of this nature, then anything which assists that task being done to the highest and safest quality is better than leaving it to the risk of trial and error.
With that caution out the way.....
First question ALWAYS with any trouble-shooting - when was it last working correctly and what has changed?
I hope I can safely assume that this Trafo WAS working prior to replacing the lead and that you have replaced the lead only as a safety precaution? If it was not working prior to replacing the cord then I suggest a qualified repair should be sought.
On the basis it was previously working, and as you have confirmed you are getting continuity from the mains plug up to the solder joints but no further, then I would suggest three options:
Yes the ceramic device is the short-circuit overload cutout - excessive current drain across any of the outputs will quickly cause the wound bi-metal element to heat up and bend away from the contact whereby the circuit will (or should) be interrupted until it cools after a few minutes and resets.
1: One possibility is a so-called 'dry-joint'. This is where the solder appears to be making a good bond but infact there is no connection or very high resistance within the joint - usually this results from movement while the solder is still fluid, or incorrect temperature (not hot enough). Remember when soldering you always heat the wire and/or the contact terminal and then apply your solder to the join, not directly to the soldering-iron tip. If the join is hot enough, the solder will flow easily through it.
2: The next thing I would check is whether the very fine wires which lead from the circuit breaker to the primary winding are still ok? (they are within the rigid plastic sheathing) - I have had them break quite easily during handling and that is definitely a show-stopper.
3: Finally, yes the circuit breaker could be faulty, and you should be able to determine this with a continuity test. If it is faulty, do NOT be tempted to by-pass it, that would be foolish in the extreme. Time for a new Trafo.
Frankly, my suggestion would be to check these things, but check them ONLY with your meter. Even if you do find the problem, please then seek a second opinion BEFORE applying mains-power.
Take the Trafo to a qualified appliance repair person or electrician and have them double-check your work. With any luck they'll commend you not only for a job well-done, but also for your common-sense and foresight in having the repair checked prior to 'going live' as it were. On the other hand, if they find it to be a sloppy attempt and slap you around the face with a wet fish then I would fall to your knees and buy him a beer - he probably just saved your life
Once again, I cannot caution you enough.
Check, check and double-check.
Regards
Steve
Edited by user 05 January 2018 05:25:19(UTC)
| Reason: Typos, spelling
