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hypa_dude
Joined: 30 Oct 2010 Posts: 1 Location: Memphis, TN
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Posted: Wed Nov 03, 2010 6:13 pm Post subject: transformer smokes |
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I am repairing a power supply for a scientific instrument. When I recieved it, it would not turn on. I opened the case and found a blackened bridge rectifier. Having repaired quite a few power supplies, I was thrilled that a repair was so obvious . . . until . . .
The instrument turned on right away after replacing the bridge rectifier, but started smoking after a few minutes of being on. The source of the smoke is the transformer, which still smokes when it is removed from the circuit. I think what happened is that when the bridge rectifier shorted, it overdrew the transformer and damaged it. I'm trying to find a suitable replacement.
The transformer is german and I've obtained a data sheet, but it is also in german. The pinout (anschlussbelegung) seems to have gotten the primary and secondary backwards, but this is what it says:
sekundar: Pin:
2 x 115V, AC A=4+8; B=6+10
I've figured out that this means the primary is designed for a 115V source and the the coils from 4 to 8 and 6 to 10 are the two primaries. The power supply has these wired in parrallel, although there are some jumpers that allow it to be wired in series for a 220V source.
Now, this is the confusing part
primar: Pin:
2 x 21V, AC 22-21-20
2 x 20V, AC 17-15-13
2 x 11V, AC 16-15-14
1 x 6V, AC 24-23
I have no idea how to interpret this. Also, I think that these are unloaded voltages, because the top of the data sheet says:
50V, 4,5A
9V, 2,0A
6-56V, 0.3A
2x19V, 0,5A
which doesn't match any of the pinout voltages. Does anyone have any ideas? I can share the data sheet if you think it would help, but it's like deciphering a german cryptogram. My german colleague can't even figure out some of the technical abbreviations. |
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jts1957
Joined: 24 Nov 2008 Posts: 2476 Location: Far, Far Away
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Posted: Wed Nov 03, 2010 7:51 pm Post subject: |
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primar: Pin:
2 x 21V, AC 22-21-20
2 x 20V, AC 17-15-13
2 x 11V, AC 16-15-14
1 x 6V, AC 24-23
Assuming transformer has that many pins, I'll take a stab:
Three secondaries:
One= 1 x 6V, AC 24-23 (6VAC across pins 23 & 24)
Two= 2 x 21V, AC 22-21-20 (21VAC across pins 20 & 21 AND pins 21 & 22. Pin 21 is center tap. 42VAC across pins 20 & 22.)
Three= 2 x 20V, AC 17-15-13 AND 2 x 11V, AC 16-15-14 (20VAC across pins 13 & 15 AND pins 15 & 17. Pin 15 is center tap. 40VAC across pins 13 & 17.) (11VAC across pins 14 & 15 AND pins 15 & 16. Pin 15 is center tap. 22VAC across pins 14 & 16.)
Another way to visualize would be to draw a let's say 3" tall winding. Put a tap at the top and bottom, one in exact center, and one each above and below the center one at appropriate distances. Label top tap 13, next one down 14, etc. to the bottom one 17. 15 is center tap to BOTH of third secondary winding. _________________ You're over there, I'm over here. |
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