Know the pinout and trace IC offline flyback code

• Know the pinout and trace IC offline flyback code
  Posted by salviador on 09 May, 2024 10:28
• 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:
  
  

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• #1 Reply
  Posted by fzabkar on 09 May, 2024 17:47
• 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).
• #2 Reply
  Posted by Harry_22 on 10 May, 2024 12:14
• Check the case

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• #3 Reply
  Posted by salviador on 11 May, 2024 07:27
• Thank you !!! it's exactly what I was looking for.
  Can I ask you where that search engine is located?
  
• #4 Reply
  Posted by Harry_22 on 11 May, 2024 08:42
• https://vip-cxema.org/index.php/online-raschjoty/393-podbor-shim-kontrollera-po-vyvodam
• #5 Reply
  Posted by salviador on 11 May, 2024 11:40
• thanks very kind
• #6 Reply
  Posted by Harry_22 on 14 May, 2024 16:32
• I’m just repairing TDK-Lambda KPSA10-24. It has a RS2042 similar controller.
  It is not in the list.

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• #7 Reply
  Posted by salviador on 14 May, 2024 17:11
• It's a battery charger for my wheelchair, charged at 24Vdc
  
  

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• #8 Reply
  Posted by salviador on 14 May, 2024 17:13
• Quote from: salviador on 14 May, 2024 17:11

  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
• #9 Reply
  Posted by Harry_22 on 14 May, 2024 17:26
• 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.

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• #10 Reply
  Posted by salviador on 15 May, 2024 07:47
• 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
  
  

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• #11 Reply
  Posted by Harry_22 on 15 May, 2024 11:45
• Yes I see. How did you understand that the controller was faulty? Did it explode?
• #12 Reply
  Posted by salviador on 15 May, 2024 13:19
• 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
• #13 Reply
  Posted by Harry_22 on 15 May, 2024 16:47
• 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.
• #14 Reply
  Posted by Harry_22 on 15 May, 2024 20:53
• Starting the controller using a soldering iron.
  
  
• #15 Reply
  Posted by salviador on 20 May, 2024 10:11
• 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
  
  

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• #16 Reply
  Posted by Harry_22 on 27 May, 2024 17:24
• 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.
  
  

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