How to make 2*15V secondaries to 1*30 V?

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Hi!

In order to repair an old Rotel Receiver I have to exchange its broken transformer (single secondary winding, 1 * 30 V AC, fault: there is not 1 * 30 V on the output, but about 300 V...)

I have a 2 * 15 V 100 VA transformer at hand (which would be enough for this receiver), so I would like to double the voltage.

I once wrongly assembled another supply and suddenly produced double the voltage I wanted, with the schematic below (Edit: the 30 0 30 is wrong, should be 15 0 15!!. So would this be the way to do it right now, where I need the double voltage?

Any suggestions?

Thanks,

Arndt
 

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Hi!

Well, thanks for the answer...

While checking with a toroid I had lying around (but does not fit inside the case) I found out that actually one part of the rectifier (a rectifier split into two discrete parts, each with two diodes) was blown, AND that my multimeter is a little bit broken (the decimal point jumps to and fro), therefore the original transformer might even be still OK 😉 ...

Anyway, exchanged the broken rectifier devices for 4 * MUR860, used my toroid, and while I was at it, exchanged every cap for a brand new Panasonic FC, and all coupling caps for Wima FKP1 and FKP2, and all transistors, as well...

And it works, and I am alwqays amazed at how good these very simple (and believe me, the amplifier part inside of this Rotel receiver is a very simple design) and old amps sound... a warm and pleasing sound...

And those old tuners seem to always sound better than their modern counterparts...

Won't be the last old - broken or unbroken - audio device I will refurbish... This one is for my parents...

Well, bye,

Arndt
 
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