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evh
Joined: 06 Sep 2006
Posts: 12
Location: england
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 Posted: Mon Dec 14, 2009 8:08 pm Post subject: SMD marking codes |
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I am trying to fix my Digital picture frame.The LCD back light lamp doesn't light on.Both end transistors of the inverter are gone.Both are the same SOT89 and there are 2 lines mark - DK and RN.
Searching on the Net gave me different results-PNP,NPN,MOSFET...
I looked the PCB and it seems they are NPN but not sure...I can see the "collectors" are connected to both terminals of the transformer's coil,which mid terminal goes to +9v.The "emitters" goes to ground...
How to find out the type and parameters of the transistors? |
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joester
Joined: 03 Dec 2009
Posts: 35
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| Posted: Mon Dec 14, 2009 9:43 pm Post subject: |
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There should be a manufacturers mark on it as well.
If you can post a reasonable photo of the component, I might be able to help you.
Joe |
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evh
Joined: 06 Sep 2006
Posts: 12
Location: england
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| Posted: Tue Dec 15, 2009 1:40 pm Post subject: |
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| joester wrote: | There should be a manufacturers mark on it as well.
If you can post a reasonable photo of the component, I might be able to help you.
Joe |
There is no manufacturers mark on it.It is too small (SOT89) and there are just these letters:
upper line- DK
lower line- RN
For now I am unable to make a good picture,my camera has no good zoom... |
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joester
Joined: 03 Dec 2009
Posts: 35
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| Posted: Wed Dec 23, 2009 9:30 pm Post subject: |
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| Please don't think I've forgotten you... Not much to go on, but I'm trying... |
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evh
Joined: 06 Sep 2006
Posts: 12
Location: england
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| Posted: Wed Dec 23, 2009 9:41 pm Post subject: |
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| joester wrote: | | Please don't think I've forgotten you... Not much to go on, but I'm trying... |
Thanks |
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russ_connolly
Joined: 08 Jan 2010
Posts: 2
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| Posted: Fri Jan 08, 2010 10:32 am Post subject: Similar problem |
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| Hi I have a photo frame with the same problem, caused by using the wrong power supply. I have pictures of the components and will send them to the email address as I cant see how to attach to post |
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evh
Joined: 06 Sep 2006
Posts: 12
Location: england
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| Posted: Fri Jan 08, 2010 11:51 am Post subject: Re: Similar problem |
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| russ_connolly wrote: | | Hi I have a photo frame with the same problem, caused by using the wrong power supply. I have pictures of the components and will send them to the email address as I cant see how to attach to post |
I didn't find the transistor codes.I found that can put any npn switching transistors.
I removed SMD transistors and connected spots by wires to external transistors BD385 which I removed from old TV.They are quite big but there is a lot of space.
For now everything is working fine. |
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russ_connolly
Joined: 08 Jan 2010
Posts: 2
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| Posted: Sat Jan 09, 2010 8:42 pm Post subject: |
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| Thanks to the previous post I have also been able to fix the photo frame, I used 2 npn transistors labelled 9014 from an old BT answer machine. |
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