Kawai KDP 80 Electronic Piano Dead

[pavb2]

Hi all

Glad to join the community. I have a Kawai KDP 80 Electronic Piano and can't get anything out of it. I've traced the 230 volt supply through the board and have 230 volts at the primary side of the transformer a Bando KT-031. The problem is I don't know what the secondary supply from the transformer should be and can't get any information I've tried Kawai and their distributors etc. The secondary is the two blue wires on the right of the picture.

I've got the service manual attached

but can't see what the secondary is any help appreciated.

 

[ChrisP58]

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

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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)

 

[pavb2]

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?

 

[Nigel Goodwin]

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?

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.