dead transformer on ceramic oven

[petehall347]

Re: dead transformer on ceramic oven

is there room for a regular transformer to be mounted ?

[Wolf1977]

Re: dead transformer on ceramic oven

Has anyone encountered a similar problem to mine? and has put in place of the first transformer which is TA105/F transformer TA70/B?

[Wolf1977]

Re: dead transformer on ceramic oven

hi again
just i want to ask to be sure
i want to test the rest circuit with an external power supplier to see if its ok
the transformer at the output has 2 outputs 12 vac 250 ma each and are connected parallel and go to the input of a bridge rectifier and the output of bridge connected on electrolytic capacitor 1000uf/35volt
i connected 12vdc to the pins positive and negative of the capacitor and the circuit is dead i measure on the other pcb that it has the controller and i have 5 volt
so i wanted to ask i dint think to needs the circuit more volatage from 12 volt to work do you agree ;

[R_J]

Re: dead transformer on ceramic oven

12 volts AC would produce approx.. 17VDC

[Wolf1977]

Re: dead transformer on ceramic oven

show with 12 volt maby its not operate
although pose produces 5 volts nothing lights up so it can play a role and I have to give it 17 volts correctly
Of course this board was connected to a network where there was some overvoltage and the pos transformer I have reported inflated so I keep my doubts about the rest of the circuit

[redwire]

Re: dead transformer on ceramic oven

What voltage are the relay coils? They are also run off the raw DC. I see a blue PTC or MOV next to the transformer, I wonder what it does.
But I am assuming the 5V rail is the main one.

EGO 75.13051.10B oven board repair

[Wolf1977]

Re: dead transformer on ceramic oven

The PTC from what I know is for current limitation I had given the positive pole of the power supply first there and from its other foot to the positive of the electrolytic capacitor and then I put it and directly on the electrolytic did not change anything the relays are 12 volts I checked if any integrated more of the processor warms up all well just does not command to light anything by pressing with my finger the black buttons

[redwire]

Re: dead transformer on ceramic oven

If there is no crystal on the board the MCU might rely on mains AC for 50/60Hz clock (timekeeping) and be waiting for pulses on that?
That is the last thing I can think of, but we have no pictures of the board to figure out what the transformer completely does.

You said a power surge killed the transformer in the first place, it is bulged out?
So the 5V rail is OK, but the display is dead? Otherwise I would guess the MCU is dead or other parts are damaged.

[Wolf1977]

Re: dead transformer on ceramic oven

there is not crystal

[redwire]

Re: dead transformer on ceramic oven

Then the MCU is using RC oscillator which is not very accurate, it would not be good enough for a time clock. Does the oven have this feature? Say a 3hour timer or something?

There is a chance the MCU needs AC pulses from transformer secondary for the firmware to work.
You can look for a small trace leaving transformer secondary and then a diode and resistor to a MCU pin.

I just don't want you to write off the board as bad if it's only the transformer.

[Wolf1977]

Re: dead transformer on ceramic oven

Unfortunately I couldn't find a line going to the pins where the oscillator crystal connects the processor is atmega16l and the legs of the crystal go to two islands in the air I can't find where they go the board is 0000 980,120-02 yl145 t105