Kawai KDP 80 Electronic Piano Dead

pavb2 said:

I've bought this transformer which I'll fit next week. I would have liked an 18 volt tapping just in case the 12 volt doesn't work, the next tapping up is 24 volts which I'd be reluctant to put through the circuit

CHINT NDK Control Circuit Panel Transformer 230-415V Output 12,24,48,110,230Volt | eBay UK

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I would not use that particular transformer for this purpose.

Your link does go to multiple transformers, but I'm assuming that you're using the 50VA unit.

Now, I haven't looked at the full datasheet for the transformer, but the VA rating is for the entire transformer. Although it does have a 12 volt tap, it is nominally a 240 volt secondary. If the 50VA rating is for the max secondary voltage, then the VA rating of the 12 Volt tap may be as low as 2.5VA.

Now, this is a pessimistic view, and you're likely to get more than the minimum, but probably not the full 50VA. It will work for a while, but all of the I^2 R secondary heating is within 4% of the secondary winding.

Also, I'm not to keen on having a secondary referenced 240 VAC point near what should be a safe, low voltage system. (even if it is shrouded)

Thanks I didn’t realise that the 12 volt secondary output would not be 50 va. I’ll put it on anyway to test the piano. What are the implications though is it a case that the transformer will overheat?

pavb2 said:

Thanks I didn’t realise that the 12 volt secondary output would not be 50 va. I’ll put it on anyway to test the piano. What are the implications though is it a case that the transformer will overheat?

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Possibly, try it and see - it really depends how the transformer was made - and specifically what type of wire was used on the low voltage windings.