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Electronics => Repair => Topic started by: Brilliant_Tankers on April 05, 2024, 07:08:06 pm

Title: Inverter repair on L6599AD - heating transformer
Post by: Brilliant_Tankers on April 05, 2024, 07:08:06 pm
Hello friends,
I need help in repairing a plate from a bakery oven, model PE1725D0-V1.
The plate was damaged as a result of flooding. I have replaced the components marked in red. Instead of L6599AD, I used L6599D and diodes other than the indicated markings.
[attach=1]

The result is that the inverter started and I have 12V at the output(probably the correct value). However, the main transformer reaches a very high temperature. After a few minutes it is over 80 degrees.  Could I have made a mistake, wrong selection of components or have something else damaged? or is it due to the design of this inverter? I attach the documentation of the driver and ask for hints. 
https://www.st.com/resource/en/datasheet/l6599.pdf (https://www.st.com/resource/en/datasheet/l6599.pdf)


Title: Re: Inverter repair on L6599AD - heating transformer
Post by: m k on April 10, 2024, 07:53:49 pm
Can you see the type of the transformer?

Many transformers are designed to be hot, over 100C is not yet abnormal.
Title: Re: Inverter repair on L6599AD - heating transformer
Post by: Brilliant_Tankers on April 11, 2024, 05:26:36 pm
Hello,
thank you for your interest.
The transformer is marked ICES-EBM CN017325(probably)
[attach=2]
It seems to me that it heats up too fast and too much. The resistance, measured on the secondary side on the capacitor is about 1k, so it doesn't seem to be overloaded. I am attaching a photo from a thermal imaging camera. 
[attachimg=1]
Title: Re: Inverter repair on L6599AD - heating transformer
Post by: m k on April 13, 2024, 09:01:57 am
Seems that the net is not exactly full of datasheets of these transformers.

You can start checking how secondary side reacts when load increases.

All energy goes trough that transformer, so it can be as it should.
TL431 is referencing how PS2561 is driving the switcher.
Transformer's secondary side before diode pair should have a clear effect when load changes.
Output voltage should also be that 12V and not follow the load.