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Old 11-14-2021, 01:17 AM   #1
dkneyle
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Default LG VCR-DVD RC689D SMPS Switching IC identification

After sitting in Standby mode for years(?) the owner decided to power up and play a CD. At which point the magic smoke emerged and it died.

Upon opening I can immediately see the main charge capacitor has dropped its guts (literally). The switching IC is completely physically destroyed so I can't read any type number. I should be able to work my way through the other components; I can usually get a SMPS going. (I can see at least one bulging electro; they'll all get replaced.) But I'm hoping someone might be able to suggest the most likely six-legged IC that would be used?

If it helps at all, board number is EAX39561401

Oh, by the way, I'm pleased to see all these components sacrificed themselves in order to save the life of the 10c fuse, which is perfectly fine!
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Old 11-14-2021, 02:00 AM   #2
vinceroger69
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

Could it be a str w6251 is there a ebr number on the board
https://elektrotanya.com/lg_ebr42894...wnload.html#dl
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Old 11-14-2021, 04:03 PM   #3
dkneyle
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

Quote:
Originally Posted by vinceroger69 View Post
Could it be a str w6251 is there a ebr number on the board
https://elektrotanya.com/lg_ebr42894...wnload.html#dl
Yes, the EBR on the board is EBR42893730. What does this tell you?

And what makes you conclude that the switching IC could be a STR-W6251?

Thanks for your help! - David
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Old 11-14-2021, 04:15 PM   #4
R_J
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

IC101 is a STR-W6251 according to the schematic
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Old 11-14-2021, 04:20 PM   #5
dkneyle
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

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Originally Posted by R_J View Post
IC101 is a STR-W6251 according to the schematic
You have a schematic for this board? I'd like to get my hands on that if possible.
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Old 11-14-2021, 05:00 PM   #6
R_J
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

The one I have is for a RCT689H, Page 46 smps schematic, Page 61 board layout
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Last edited by R_J; 11-14-2021 at 05:29 PM..
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Old 11-14-2021, 05:15 PM   #7
lotas
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

Quote:
Originally Posted by dkneyle View Post
You have a schematic for this board? I'd like to get my hands on that if possible.
lg_ebr42894130_sch
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Old 11-14-2021, 05:28 PM   #8
dkneyle
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

Quote:
Originally Posted by R_J View Post
The one I have is for a RCT689H
Thank you so much I'm sure it's probably identical. I'll check my spare parts box; I strip down TVs that are unrepairable and I have many of these 6-legged SMPS ICs. Hopefully I have STRW6251?

Are you aware of any common substitute if I strike problems?

(Out of interest I've been checking what else needs replacing. The 2.7 ohms power resistor seems to have gone O/C. My DC measurements of the zener diodes suggests they might be blown. But at least the fuse was saved!)
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Old 11-14-2021, 05:53 PM   #9
lotas
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

Check, replace.
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Old 11-14-2021, 08:33 PM   #10
R_J
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

I would also replace C108 (33f/35v) on the vcc of the ic.
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Old 12-03-2021, 08:58 PM   #11
dkneyle
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Default Re: LG VCR-DVD RC689D SMPS Switching IC identification

All working again. Got the STR-W6251 out of China. Virtually all the components on the hot side needed to be replaced. Both zener diodes were defunct. Just to be sure I changed out all the electro caps on the cold side.
Another piece of electronic saved from landfill!
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