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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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HH Scott 222C TR12-3-1 Transformer Replacement Info Needed
HH Scott 222C TR12-3-1 Transformer Replacement Info Needed
The power transformer in my 222C Amplifier is shorted, and I need the voltages, (HV Secondary, etc) in order to locate a replacement. The transformer is marked TR12-3-1, The tube complement in my 222c is: one 5ar4 two 6GH8 four 12ax7 four 7189 Any info is appreciated. Many thanks in advance for your assistance, Dan |
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The power transformer in my 222C Amplifier is shorted, and I need the
voltages, (HV Secondary, etc) in order to locate a replacement. The transformer is marked TR12-3-1, The tube complement in my 222c is: one 5ar4, two 6GH8, four 12ax7, four 7189 Any info is appreciated. Dan, You'll need a five volt winding for the rectifier tube filament (unless you use a pair of diodes to sub for the tube) and a six volt winding for all the other tube filaments. Those windings will be pretty hefty to carry that much current, perhaps 1.5A for the rectifier and 4 or 5 amps for the other tubes (wild guesses). Look at the thickness of the wires on the old tranny. If you can scrounge up a receiving tube manual, you can calculate the totals. To get a rough estimate of the total B+, look at the voltage rating of the filter caps on the rectifier tube. There is normally about 10% "headroom" so the caps never see anything at or over their rated voltage even if the AC line goes high. Keep in mind that if you substitute diodes for the rectifier tube, the B+ will not be loaded until the other tube filaments warm up, so the B+ will go immediately to the peak value when the unit is powered up. Also, there is some voltage drop when using a tube as a rectifier, so subbing diodes with the original transformer (if you find an exact replacement) may exceed the cap voltage rating. Multiply the transformers rated secondary voltage times 1.414 to get the peak value. For example, for a secondary rated at 260 volts, you multiply that by 1.414 to get the maximum voltage the input filter has to handle. That comes to about 367 volts DC (unloaded). With some overhead so the filter is never pushed beyond it's voltage rating, it would likely be rated at 400 volts. If the filters in your amp have a different voltage rating, you can recalculate to get an approximate value for the transformer voltage rating. Ray -- My return addy is spamblocked. To reply, remove the zeroes. |
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(Marc) wrote in message . com...
HH Scott 222C TR12-3-1 Transformer Replacement Info Needed The power transformer in my 222C Amplifier is shorted, and I need the voltages, (HV Secondary, etc) in order to locate a replacement. The transformer is marked TR12-3-1, The tube complement in my 222c is: one 5ar4 two 6GH8 four 12ax7 four 7189 Any info is appreciated. Many thanks in advance for your assistance, Dan Dan, The 222-C power transformer has the following characteristics: Primary: 117 VAC Secondary: 360-0-360 VAC @ 150 mA 50 VAC @ 150 mA 6.3 VAC @ 5A 5.0 VAC @ 2.0A www.heyboertransformer.com can rewind this transformer for $90. I've used them several times, and they deliver a great product, new long PVC leads as well. When I had mine rewound, I asked for a 200 mA HT winding, and a 3.0A 5V winding for the rectifier to allow for use of 5U4 tube. Above are the stock specifications. Best of regards, Ryan www.hotglassaudio.com |
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(Hot Glass Audio) wrote in message om...
(Marc) wrote in message . com... HH Scott 222C TR12-3-1 Transformer Replacement Info Needed The power transformer in my 222C Amplifier is shorted, and I need the voltages, (HV Secondary, etc) in order to locate a replacement. The transformer is marked TR12-3-1, The tube complement in my 222c is: one 5ar4 two 6GH8 four 12ax7 four 7189 Any info is appreciated. Many thanks in advance for your assistance, Dan Dan, The 222-C power transformer has the following characteristics: Primary: 117 VAC Secondary: 360-0-360 VAC @ 150 mA 50 VAC @ 150 mA 6.3 VAC @ 5A 5.0 VAC @ 2.0A www.heyboertransformer.com can rewind this transformer for $90. I've used them several times, and they deliver a great product, new long PVC leads as well. Thanks for the info. But did you mean: www.heyboertransformers.com ??? Thanks When I had mine rewound, I asked for a 200 mA HT winding, and a 3.0A 5V winding for the rectifier to allow for use of 5U4 tube. Above are the stock specifications. Best of regards, Ryan www.hotglassaudio.com |
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Yes, Dan. It is indeed www.heyboertransformers.com. Great company to
deal with. Call and ask for Alden. Best regards, Ryan |
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