Know the pinout and trace IC offline flyback code - Page 1
Forum section: electronics / repair

author: salviador
author_rank: Regular Contributor
timestamp: May 09, 2024, 10:28:19 am
content: 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:

author: fzabkar
author_rank: Super Contributor
timestamp: May 09, 2024, 05:47:22 pm
content: 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).

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 10, 2024, 12:14:15 pm
content: Check the case

author: salviador
author_rank: Regular Contributor
timestamp: May 11, 2024, 07:27:36 am
content: Thank you !!! it's exactly what I was looking for.Can I ask you where that search engine is located?

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 11, 2024, 08:42:02 am
content: https://vip-cxema.org/index.php/online-raschjoty/393-podbor-shim-kontrollera-po-vyvodam

author: salviador
author_rank: Regular Contributor
timestamp: May 11, 2024, 11:40:30 am
content: thanks very kind

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 14, 2024, 04:32:33 pm
content: I’m just repairing TDK-Lambda KPSA10-24. It has a RS2042 similar controller.It is not in the list.

author: salviador
author_rank: Regular Contributor
timestamp: May 14, 2024, 05:11:47 pm
content: It's a battery charger for my wheelchair, charged at 24Vdc

author: salviador
author_rank: Regular Contributor
timestamp: May 14, 2024, 05:13:06 pm
content: Quote from: salviador on May 14, 2024, 05:11:47 pmI purchased these 2 ICs when they arrive I'll try themCR6841OB2269

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 14, 2024, 05:26:28 pm
content: 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.

author: salviador
author_rank: Regular Contributor
timestamp: May 15, 2024, 07:47:56 am
content: 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

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 15, 2024, 11:45:01 am
content: Yes I see. How did you understand that the controller was faulty? Did it explode?

author: salviador
author_rank: Regular Contributor
timestamp: May 15, 2024, 01:19:32 pm
content: 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

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 15, 2024, 04:47:25 pm
content: I have the same problem but it occurs time to time.In case of failure the voltages are:FB=0VIN=24.7 (I have 126VDC source)VDD=17.25others zeroBut 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.

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 15, 2024, 08:53:27 pm
content: Starting the controller using a soldering iron.

author: salviador
author_rank: Regular Contributor
timestamp: May 20, 2024, 10:11:02 am
content: 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

author: Harry_22
author_rank: Frequent Contributor
timestamp: May 27, 2024, 05:24:19 pm
content: Just changed fault RS2042 with CR6842.PS also works well under full load 24VDC @ 0.4AOn the right side of the controller there is MOSFET and at the bottom right is a rectifier diode.