Author Topic: Know the pinout and trace IC offline flyback code  (Read 1340 times)

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Offline salviadorTopic starter

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Know the pinout and trace IC offline flyback code
« on: May 09, 2024, 10:28:19 am »
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:

 

Online fzabkar

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Re: Know the pinout and trace IC offline flyback code
« Reply #1 on: May 09, 2024, 05:47:22 pm »
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).
 

Offline Harry_22

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Re: Know the pinout and trace IC offline flyback code
« Reply #2 on: May 10, 2024, 12:14:15 pm »
Check the case
 

Offline salviadorTopic starter

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Re: Know the pinout and trace IC offline flyback code
« Reply #3 on: May 11, 2024, 07:27:36 am »
Thank you !!! it's exactly what I was looking for.
Can I ask you where that search engine is located?
 

Offline Harry_22

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Offline salviadorTopic starter

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Re: Know the pinout and trace IC offline flyback code
« Reply #5 on: May 11, 2024, 11:40:30 am »
thanks very kind
 

Offline Harry_22

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Re: Know the pinout and trace IC offline flyback code
« Reply #6 on: May 14, 2024, 04:32:33 pm »
I’m just repairing TDK-Lambda KPSA10-24. It has a RS2042 similar controller.
It is not in the list.
 

Offline salviadorTopic starter

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Re: Know the pinout and trace IC offline flyback code
« Reply #7 on: May 14, 2024, 05:11:47 pm »
It's a battery charger for my wheelchair, charged at 24Vdc

 

Offline salviadorTopic starter

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Re: Know the pinout and trace IC offline flyback code
« Reply #8 on: May 14, 2024, 05:13:06 pm »
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
 

Offline Harry_22

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Re: Know the pinout and trace IC offline flyback code
« Reply #9 on: May 14, 2024, 05:26:28 pm »
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.
« Last Edit: May 14, 2024, 06:58:20 pm by Harry_22 »
 

Offline salviadorTopic starter

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Re: Know the pinout and trace IC offline flyback code
« Reply #10 on: May 15, 2024, 07:47:56 am »
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

 

Offline Harry_22

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Re: Know the pinout and trace IC offline flyback code
« Reply #11 on: May 15, 2024, 11:45:01 am »
Yes I see. How did you understand that the controller was faulty? Did it explode?
 

Offline salviadorTopic starter

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Re: Know the pinout and trace IC offline flyback code
« Reply #12 on: May 15, 2024, 01:19:32 pm »
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
 

Offline Harry_22

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Re: Know the pinout and trace IC offline flyback code
« Reply #13 on: May 15, 2024, 04:47:25 pm »
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.
 

Offline Harry_22

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Re: Know the pinout and trace IC offline flyback code
« Reply #14 on: May 15, 2024, 08:53:27 pm »
Starting the controller using a soldering iron.

« Last Edit: May 15, 2024, 09:00:40 pm by Harry_22 »
 

Offline salviadorTopic starter

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Re: Know the pinout and trace IC offline flyback code
« Reply #15 on: May 20, 2024, 10:11:02 am »
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

 

Offline Harry_22

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Re: Know the pinout and trace IC offline flyback code
« Reply #16 on: May 27, 2024, 05:24:19 pm »
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.

« Last Edit: May 27, 2024, 07:37:25 pm by Harry_22 »
 


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