Philips Disk Jockey Major output transformer

Ernst Erb Bernhard Nagel Martin Renz 
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Forum » Technique, Repair, Restoration, Home construction ** » Radios: how to get parts for old radios » Philips Disk Jockey Major output transformer
David Humphrey
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14.Jan.22 21:35
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? Philips Disk Jockey Major NG-5050 

Hi everyone.

I have refurbished a Philips Disk Jockey Major model no NG-5050 and need a replacement speaker output transformer part number MK.514.23. I cannot find the trannys characteristics on the web and am too much of a newbie to this hobby to derive them from the wiring diagram.

Can anyone offer any suggestions please?

Torbjörn Forsman
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14.Jan.22 22:22

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An output transformer from just about any valve radio for AC supply with an EL84, EL41 or similar output valve, and a loudspeaker of approximately the same impedance as the speaker fitted to the NG5050, will work well. Note that most valve televisions and AC/DC radios are using output valves optimized for a much lower load impedance, so transformers from such units may not necessarily work well. There are also a few AC radios using fairly low B+ voltage and an output valve for lower impedance, like the EL86 or ECL82, those transformers should also be avoided in this case.

We can assume that the output valve, at the operating point used in this amplifier, wants to have a load impedance of around 7000 ohms. If, for example, the speaker impedance is 5 ohms, the transformer's impedance ratio should be 7000/5 = 1400:1 . And then the voltage transformation ratio will be the square root of the impedance ratio - i. e. about 37:1 .

David Humphrey
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18.Jan.22 07:43

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Thank you Torbjörn.

That is really helpful.  I will see what I can find as a replacement.


Bernhard Nagel
Bernhard Nagel
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22.Jan.22 13:19

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please make a new model suggestion for the Philips Disc Jockey Major NG-5050, this model isn't listed in RMorg until yet.

Thank you.