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Old 25th May 2002, 01:21 PM   #1
fezz is offline fezz  United Kingdom
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Default HELP! Melting transformer

i have just turned on my first project, a powerfollower. the plastic around my 300va transformer has shrunl/melted and the insulation on the wires has melted, i have no idea what the problem - this is only happening to one channel
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Old 25th May 2002, 03:01 PM   #2
paulb is offline paulb  Canada
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Default More information?

We'll need more information to help you out. What amp circuit? What is the power supply circuit?
In general:
Use an ohmmeter to check for short circuits. You've probably got one. Note the transformer secondary will be very close to 0 ohms.
Use a variac to power up for the first time, or temporary power resistors to check current levels. Even a light bulb in the AC side can be used.
Run up the power supply separately. WIth no amp connected, you can use smaller fuses - if they blow, you've isolated the problem.
Got any pictures? Oops, I guess that's like Morbid Curiosity...
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Old 25th May 2002, 03:10 PM   #3
paulb is offline paulb  Canada
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Also check out this thread:
I finally fired up my Leach Amp!!!!
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Old 25th May 2002, 03:24 PM   #4
fezz is offline fezz  United Kingdom
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it is a power follower. the power supply is made up of just two bridge rectifiers - one for each secondairy, capacitors and a transformer

what should i connect the ohm meter between?

should the light bulb go before or after the transformer?

i will try the psu on it's own now.

pictures may come if you want them (it's a mess)
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Old 25th May 2002, 03:43 PM   #5
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There is definately a short circuit for a load. If you are trying to get plus and minus power supplies, a single bridge rectifier will do fine. Do you have a fuse on the primary side? Are there fuses on the secondary side? This will tell you right away if there is a problem without damaging the transformer. Use slo-blo fuses when using inductive loading (i.e transformer primary).
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Old 25th May 2002, 06:24 PM   #6
fezz is offline fezz  United Kingdom
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thanks for the quick replies, it is one of the secondarys, i will add fuses on the secondary and primary coils when i get a new transformer. for now, have a look at this pic (sorry about the size, i took it on low quality)
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File Type: jpg transformer.jpg (59.6 KB, 313 views)
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Old 25th May 2002, 06:41 PM   #7
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maybe a short in the primary side of transformer...
it hapen to me in Kora Hibride...the transformer became very hot...but i have find that was two turns touching...i pull them apart put some vernish...and it riturns working properly...
I' m a lucky man!!!
But if that is not your problem you may check for oscilation in that chanel..or short circuit!
Good luck!
Regards
Jorge
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Old 25th May 2002, 06:41 PM   #8
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What is the manufacturer and model of this transformer? Does it have a shield wire? It looks like it might but I cant tell. If so this should be attached to the star ground point. What are the wire color codes for your transformer? Typically orange and white are line neutral, black and brown are the line, there are some normal colors for the secondaries too but I will not speculate. If the two dot ends or the non-dot ends of the seconaries are connected, you are driving a short circuit. On the secondaries, a dot end and a no-dot end should be connected and become the common line to be attached to the star ground point. This may be what caused your problem. An idle transformer should dissipate little heat.

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Old 25th May 2002, 08:43 PM   #9
fezz is offline fezz  United Kingdom
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there is no ground wire/sheild wire

i think it is made by talema

there are red and black for one secondary and orange and yelow for the other.
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Old 25th May 2002, 11:55 PM   #10
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After doing a little research, if indeed your manufacturer is Talema, then that means that it is made by Amveco. Their color code is found at amveco.com. The color code that your named sounds a little suspect. The smaller wires should be for the AC line and the larger wires are the secondaries.
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