Transformer substitution - Sanyo DP42849-01

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

I carefully unwrapped a bad transformer. Those numbers are only for one side so they are probably incorrect. Each primary and each secondary have the number of turns I posted in post #2.

[budm]

Re: Transformer substitution - Sanyo DP42849-01

You can use LCR meter. BTW, how did you determine the turn count? There are two High voltage secondary windings, and two primary windings (connected in parallel) from what I see looking at the bottom side of the board.

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

Now, would I need to get the inductance from the secondary or primary? And powered on or off?

[stj]

Re: Transformer substitution - Sanyo DP42849-01

o.k.
at these prices - not worth making stuff anymore!
http://www.ebay.de/itm/251555691479

you can get inductance with an LCR meter.
this thing does it all!!
(i'm getting one!)

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

I was just thinking about that. Because whatever the frequency is between the chip and the FET, it will be the same at the transformer.

Now, I still need to figure how to determine the transformers inductance (LCR meter?), and it's input voltage and current rating. Is the input voltage the same as at the PFC?

[stj]

Re: Transformer substitution - Sanyo DP42849-01

frequency counter should be fine if you use it between the chip and fet.
and put a ceramic cap between the counter & target circuit to block dc.

just remember that the counter is 5v so it really wont like higher voltages on it's pins.
the same applies to comercial counters btw.

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

So that counter would probably fry?

Post #2 has turns of primary and secondary. Turn ratio would be 1:4.78

DCR? If that's resistance, it's also in post #2.

How do I determine inductance?

[budm]

Re: Transformer substitution - Sanyo DP42849-01

You will need to know the inductance, the DCR of Primary and Secondary, the turn ratio, the power requirement, etc.
http://www.coilcraft.com/ccfl.cfm

[tom66]

Re: Transformer substitution - Sanyo DP42849-01

I wouldn't stick that frequency meter within 2 foot of any high voltage or mains potentials.

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

Sweet! So we have the circuits resonant frequency. Or, will have once I build the counter. Now I guess all that's left to determine is the transformer's input voltage and current. I get nothing with my volt meter because the frequency is too high.

[stj]

Re: Transformer substitution - Sanyo DP42849-01

http://danyk.cz/avr_fmetr_en.html

[stj]

Re: Transformer substitution - Sanyo DP42849-01

before you spend much money,

there are nice projects.
make one.
https://duckduckgo.com/?q=atmel+70mh...-wt&kp=-1&kv=1

another option, the datasheet implies that the frequency is directly related to the voltage on one of the pins.
so maybe meter the voltage to calculate the frequency.

finally - check for cheap clone transformers.
like here - this seller has a bunch.
http://stores.ebay.com/lcd-led-parts

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

So one of these would work then?

http://www.ebay.com/itm/OSCILLOSCOPE...item19eae5e6d7

http://www.ebay.com/itm/Frequency-Co...item1e8cf01fd0

[stj]

Re: Transformer substitution - Sanyo DP42849-01

frequency counter i think you mean.

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

OK, that was the one I originally thought. The data sheet is in post #4. But it only says 30khz to 500khz. So I guess I'll need someone with an oscilloscope right?

[stj]

Re: Transformer substitution - Sanyo DP42849-01

controller

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

Are these the FETs?

Edit: Only other ICs on the board are op-amps and standby controller.

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

Here's a pic of the bottom and a link to one of my older threads which has some good closeups of the bottom.

https://www.badcaps.net/forum/showthread.php?t=33261

[stj]

Re: Transformer substitution - Sanyo DP42849-01

no, that's the pfc circuit.

trace the transformers back to the fets that switch them.
then trace the gate pin from those fets to find the drive chip.

does it have parts on the other side of the board?

[lookimback]

Re: Transformer substitution - Sanyo DP42849-01

Maybe it's this one?