LCD Screen flashing

desferg

New Member
I have a faulty ETIV controller for an air compressor. Once power is applied( 24V AC)it takes approx 30 seconds for the LCD screen to illuminate, at the same time a PCB mounted transformer starts to buzz very loudly.
The LCD screen flickers on and off at a high frequency and at times displays the software version on the LCD. The buttons on the unit once pressed dont do anything.
I cant find any information on the transformer online. I removed it from the board, it has 3 pins on primary and 3 pins on secondary. There is approx 1Ohm resistance across each set of pins. Each pin has continuity to the 2 other pins. There is no continuity from primary to secondary as expected. If freezer spray is applied to the transformer the buzzing will temporarily stop. Could the buzzing transformer be a red herring or could it be causing this issue? Does anyone know what sort of transformer it is? I'm not even sure which is primary side and which is secondary. One side of the transformer has 2 pins that go to 2 MOSFETS drain so presuming that's the secondary side of transformer?
 

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Buzzing could be loose lamination in the core. Also check the diodes.

What is that component on left ? A cap or L ?

Also appears to be 2 real loose windings on the transformer, its not a
bad solder connection related issue ?
 
The photo looks like a flyback transformer. Three pins on primary and secondary can suggest center-taps, snubber winding, or auxiliary winding.
 
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