Numark CDN-22S transformer problem

poynton · 23rd December 2010, 10:41 AM

Hi.

I have acqquired a Numark CDN-22S dual Cd player.

The description I was given was " not turning on".

The power supply is a conventional transformer with twin secondaries.
Input is 115 / 220v

Anyone want to guess why it won't turn on ?

Open circuit primary on the transformer .
I would guess from being put into 110v on a UK supply.

My question :- Anyone know or can measure the secondary voltage?

Thanks.
Andy

.

stephensank · 23rd December 2010, 05:39 PM

Open primaries are almost ALWAYS the result of an open thermal cutoff, located in the final layers of outer wrappings of the windings. These cutoffs are completely redundant & unnecessary in all cases where there is a line fuse, and it's a simple matter to add a line fuse on those that lack them. About 7 times out of ten, the cutoff will be connected, visibly, to the external pins(of pc mount xfmr), easily identified by having non-enameled leads coming out to wrap onto pin, so simply a matter of shifting the ac connection to the pin having both the cutoff's lead & an enameled winding lead, bypassing the cutoff. In a wired-out xfmr, it's a matter of cracking open the transformer case/outer wrappings to access & bypass the cutoff, which is, again, usually very easy.
I'm sure I don't need to add, though, that you should check for shorted power supply caps & rectifiers before powering the thing up again.

zeonrider · 23rd December 2010, 06:49 PM

Thermal switch 100%!

Regards zeoN_Rider

23rd December 2010, 10:41 AM	#1
poynton Magneto the Gravity Man diyAudio Member Join Date: Mar 2005 Location: A life on the ocean waves when I'm not at home in N. Wales (but I'm not Welsh so no sheep jokes!)	Numark CDN-22S transformer problem Hi. I have acqquired a Numark CDN-22S dual Cd player. The description I was given was " not turning on". The power supply is a conventional transformer with twin secondaries. Input is 115 / 220v Anyone want to guess why it won't turn on ? Open circuit primary on the transformer . I would guess from being put into 110v on a UK supply. My question :- Anyone know or can measure the secondary voltage? Thanks. Andy . __________________ If it ain't broke, break it !! Then fix it again. It's called DIY !

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23rd December 2010, 05:39 PM	#2
stephensank diyAudio Member Join Date: Oct 2006	Open primaries are almost ALWAYS the result of an open thermal cutoff, located in the final layers of outer wrappings of the windings. These cutoffs are completely redundant & unnecessary in all cases where there is a line fuse, and it's a simple matter to add a line fuse on those that lack them. About 7 times out of ten, the cutoff will be connected, visibly, to the external pins(of pc mount xfmr), easily identified by having non-enameled leads coming out to wrap onto pin, so simply a matter of shifting the ac connection to the pin having both the cutoff's lead & an enameled winding lead, bypassing the cutoff. In a wired-out xfmr, it's a matter of cracking open the transformer case/outer wrappings to access & bypass the cutoff, which is, again, usually very easy. I'm sure I don't need to add, though, that you should check for shorted power supply caps & rectifiers before powering the thing up again.