Know the pinout and trace IC offline flyback code

[salviador]

Hi,
I'm looking for a soic8 IC of a flyback controller, I would like to trace the acronym starting from the pinout by doing reversing engineering.

The pins that I was able to identify are these:

[fzabkar]

If pin #4 connects to a low value resistor at the bottom leg of the MOSFET chopper, then it must be the current sense pin (CS).

[Harry_22]

Check the case

[salviador]

Thank you !!! it's exactly what I was looking for.
Can I ask you where that search engine is located?

[Harry_22]

https://vip-cxema.org/index.php/online-raschjoty/393-podbor-shim-kontrollera-po-vyvodam

[salviador]

thanks very kind

[Harry_22]

I’m just repairing TDK-Lambda KPSA10-24. It has a RS2042 similar controller.
It is not in the list.

[salviador]

It's a battery charger for my wheelchair, charged at 24Vdc

[salviador]

It's a battery charger for my wheelchair, charged at 24Vdc

I purchased these 2 ICs when they arrive I'll try them


CR6841
OB2269

[Harry_22]

What is about MOSFET? Is it Ok?
CR6841 is mostly the same as RS2042. But OB2269 has different default RI ~100k. It is 24k on your PCB.

Please check the following resistor.

[salviador]

That's an LM358 that should act as a current control, that resistor is actually "cooked", but with the multimeter I have 100 ohms hoping that that is the value.
IC flyback is on the right side where I removed it

[Harry_22]

Yes I see. How did you understand that the controller was faulty? Did it explode?

[salviador]

Except for that resistor, everything else shows no signs of burning. If I power it it doesn't turn on I checked with an oscilloscope and the mosfet (output pin8) has no pulses but it is not shorted

[Harry_22]

I have the same problem but it occurs time to time.
In case of failure the voltages are:
FB=0
VIN=24.7 (I have 126VDC source) 
VDD=17.25
others zero

But FB shouldn't be zero. Zero volt on FB stops working.
It turned out that one-time heating of the controller restored its functionality.

Did you measured resistance from FB pin to ground? I mean optocoupler C-E resistance.

[Harry_22]

Starting the controller using a soldering iron.

[salviador]

You're right,
I changed FB opto and replaced the flyback controller IC with this one which seems more plausible thanks to your OB2269 table

[Harry_22]

Just changed fault RS2042 with CR6842.
PS also works well under full load 24VDC @ 0.4A
On the right side of the controller there is MOSFET and at the bottom right is a rectifier diode.