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#1
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How To Operate Equipment With Blown Transformers
Casino wrote: For those of you with radios or amplifiers that have power transformers with blown primary windings, I would like to offer a temporary solution to keep your equipment working while you search for a replacement. Assuming your transformer has 6.3 volt and 5 volt windings in addition to the high voltage B+ supply, you could disconnect either the 6.3 volt or 5 volt heater/filament supply and hook-up the low voltage winding from the radio's power transformer to an external 6.3 or 5 volt AC source such as a small transformer. You will also need another transformer of the same low voltage to supply the filament/heaters. Basically, you are now running your amp or radio with a low voltage AC source and the original power transformer (with the blown primary) is now stepping-up the 6.3 or 5 volts to 700 volts CT or whatever the B+ might be. Now you can search for a replacement transformer for that old radio without missing the lastest hit music releases. Hope this helps. This would only work if the primary of the blown tranny has no shorted turns. I'd be very careful about this strategy. Patrick Turner. |
#2
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Tim Williams wrote: "Patrick Turner" wrote in message ... Snip I'd be very careful about this strategy. Especially since most amps have more VA invested in the HT winding vs. heaters; it's a physically smaller winding. Tim If you blow a tranny in an old radio, then it'd be best to connect an external large transformer with long leads into the appropriate internal connection points, to the heaters, and rectifier inputs, until such time as the original can be rewound, or the right sized or right VA tranny can be found. Tim is dead right about using the heater the heater winding as input to the rest of the set, the VA of this winding might be a lot lower than what is demanded of the HT winding. A typical radio might have 6.3v x 3.0A, The B+ might be +300 x 70 mA, so that's 21VA, but if it was more, you'd have to watch it. The 5v x 2.5 amp rectifier would also load the 6.3v winding. But a fuse would be essential, since the buggered tranny would run hot..... which wouldn't matter, since it is to be replaced anyway, hopefully with something better. If the input to the radio was at the 6.3v connection, the heaters of the set load the external temporary transformer, not the set's tranny. Patrick Turner. -- In the immortal words of Ned Flanders: "No foot longs!" Website @ http://webpages.charter.net/dawill/tmoranwms |
#3
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"Tim Williams" wrote in message ... "Patrick Turner" wrote in message ... Snip I'd be very careful about this strategy. Especially since most amps have more VA invested in the HT winding vs. heaters; it's a physically smaller winding. Tim To paraphrase you (sort'a), imagine a transformer with 1 A 6V winding, and a 1A 450V winding (hypothetical....). The only *real* trick is to have serious tonnage of transformers! stupid but proud smile |
#4
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"Shiva" wrote in message
... To paraphrase you (sort'a), imagine a transformer with 1 A 6V winding, and a 1A 450V winding (hypothetical....). The only *real* trick is to have serious tonnage of transformers! stupid but proud smile Reminds me, for that Quad 6146 PPP amp I'm going to build some day, well it'll use a 250V-or-so 2A transformer (feeding a doubler for the 600V 500mA required for full steam), and need 'only' 6.3V 10A (actually 8A IIRC, but close enough). That's a difference of about 10x the VA Of course, I'll be using a seperate filament transformer so the subject of this thread isn't applicable. Tim -- In the immortal words of Ned Flanders: "No foot longs!" Website @ http://webpages.charter.net/dawill/tmoranwms |
#6
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"Tim Williams" wrote in message ... "Shiva" wrote in message ... To paraphrase you (sort'a), imagine a transformer with 1 A 6V winding, and a 1A 450V winding (hypothetical....). The only *real* trick is to have serious tonnage of transformers! stupid but proud smile Reminds me, for that Quad 6146 PPP amp I'm going to build some day, well it'll use a 250V-or-so 2A transformer (feeding a doubler for the 600V 500mA required for full steam), and need 'only' 6.3V 10A (actually 8A IIRC, but close enough). That's a difference of about 10x the VA Of course, I'll be using a seperate filament transformer so the subject of this thread isn't applicable. Tim Care to send me a few bux for a Triad 20A 6.3 CT? It's big. It's gray. You want it. -dim ineptly tryin' to raise cash... -- In the immortal words of Ned Flanders: "No foot longs!" Website @ http://webpages.charter.net/dawill/tmoranwms |
#7
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Tim Williams wrote: "Shiva" wrote in message ... Care to send me a few bux for a Triad 20A 6.3 CT? It's big. It's gray. You want it. -dim ineptly tryin' to raise cash... Alright, I've got a few pennies on the way, but they may or may not already have been melted :-p Tim Crikey Tim, youse gotta job!!! Wonders will never cease! Patrick Turner. -- In the immortal words of Ned Flanders: "No foot longs!" Website @ http://webpages.charter.net/dawill/tmoranwms |
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