Author Topic: Transformer replacement  (Read 946 times)

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Offline Peter ETopic starter

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Transformer replacement
« on: September 03, 2019, 08:40:19 pm »
Hello all,

I am repairing a full size Yamaha digital piano with aim to donate it to a day centre.
I have some basic experience if fixing electric and electronic equipments. The piano works normally but no sounds comes out! So far with help from a few clever friends, we narrow it down to problem with Transformer. It overheats and been told it needs to be replaced. The problem is that I just find it any supplier in UK or out who supplies such specification.

The input is: 220v and outputs: 20VAC x2 & 8VACx2. (Please see the photo)

I would be grateful for any advise.

Many thanks

Peter
 

Offline james_s

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Re: Transformer replacement
« Reply #1 on: September 03, 2019, 09:17:11 pm »
It seems very unlikely that the problem is the transformer, in my entire life I think I have seen one power transformer that failed not due to something on the secondary side shorting out and overloading it to the point that it burned up.

What tests have you done to confirm that the transformer is the problem? Does it overheat with the secondary disconnected completely from the load?
 

Offline Doctorandus_P

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Re: Transformer replacement
« Reply #2 on: September 04, 2019, 07:32:18 pm »
Transformers indeed tend to be pretty reliable (but they can fail).
Wen overheating, it's usually beause the circuit behind it is faulty and draws too much current.

Does the transformer still get hot if you disconnect the secondary circuit?
How much current is drawn from each of the sectundary windings? (is it within spec?)

If it really is the transformer that is faulty, you can replace it with a few other transformers.
 


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