EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: Teza on May 17, 2019, 04:11:53 pm
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My skills:
I have only a very basic understanding of electronic components, and have not tryed to troubleshoot a circuit before.
This is my very first repair attempt, and my hope is to learn some basics when it comes to repairing electronics.
I received a Daewoo DSL19T2WC, (serial: XD089004010304) 12V, 19" LCD tv with integrated dvd from my father.
Problem description:
TV was dead after the 12V power was connected.
Opened the tv with my father earlier, and found a blown 3A fuse on the motherboard.
Later, my father attempted to repair by replacing the fuse with a 3A flat car fuse, and got standby light, and a green line on the screen when turned on, before the tv went black again (fuse ok this time).
What I have done so far:
Tested the external power supply, it gives 12V and seems to be ok.
Have searched for schematics, repair manual, service manual for the DSL19T2WC with no luck.
Opened the tv, found the mainboard model B.LT709F 8227, again searched for schematics, with no luck. (There seems to be different versions of this motherboard.)
Read thru the post https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/, (https://www.eevblog.com/forum/repair/repair-documents-and-links-sticky-me-please-mods/,) and tried finding links with schematics with no luck.
Have disconnected the motherboard from the TV, pictures below, but can't see any components that looks defect.
Top picture of the board (http://www.terjeandersen.no/forum/evvblog/Daewoo_DSL19T2WC_B.LT709F_8227_Front.jpg)
Bottom picture of the board (http://www.terjeandersen.no/forum/evvblog/Daewoo_DSL19T2WC_B.LT709F_8227_Back.jpg)
Collage of power section (http://www.terjeandersen.no/forum/evvblog/Daewoo-kretskort-mosaikk.jpg)
Questions:
1. Anyone that know where to find schematic for this motherboard?
2. I will try to measure the capacitors on the board next, to see if any of them gives strange readings. Anything I should be aware of, not to do damage to the board or the Keysight U1733 LCR meter I got for this project?
3. I have some "PTC Resettable Fuses Radial Lead 3A 72V Polyswitch Tyco Raychem RXEF300", can these be used to replace the missing fuse on this board? I think there originally was a glass fuse, soldered to the board.
Hold Current: 3A
Trip Current: 6A
Current Rating (Max): 40A
Resistance: 0.1 Ohms
Maximum Voltage: 72VDC
Size: 28.6mm L x 3mm H x 23.9mm D
Lead Spacing: 10.9mm
Would be grateful for tips on how to start looking for errors.
Thanks
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Hello,
Look at the attached pic. there is a circled component in red and white, check if there is a burnt hole at top of it.
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Have tried to measure a few capacitors but need the datasheet to compare values.
Tho I can't find the EFC WESCO CD263 series at http://www.filmcapacitors.com/ (http://www.filmcapacitors.com/) or at Farnell/elfa distrelec/mouser/digikey.
Is these capacitors sold under a different brand?
(http://www.terjeandersen.no/forum/evvblog/Measurement1.jpg)
@montarbo
After I google blown IC, I believe this IC is not burned.
(http://www.terjeandersen.no/forum/evvblog/test01.jpg)
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Do u have any bench power supply.
probably putting a car fuse and pushing the device did some damage. Connecting the bench supply starting at low voltage with a 2 amp might give a clue if there is short to ground, then u can start digging.
The ic in pic seems fine. In ur first pic " somewhat blurry" there seemed to be some burn hole at top.
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I have a PeakTech 6215 (https://www.peaktech.de/productdetail/kategorie/acdc-stabilisierte-labornetzgeraete/produkt/p-6215.html).
Connected the moterboard and adjusted the voltage slowly from 6V up to 12V, it uses 0,42A at 12V according to the psu.
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Not a short at power supply. Do u get 5 v at the connector?
Without a schematic it would be impossible.
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Thank you for the help so far!
Yes, I believe a service manual with schematics is needed.
I kind of hoped there was some faulty capacitors, but it seems to be hard too find the datasheet for those as well.
I got some strange readings on some of the capacitors, so I might get some new ones and try to replace them.
Have also tried to find a Daewoo office/webpage to get help with schematics or service manual, but also this is difficult, as it seems like most of the webpages / contact info is not valid anymore.
info@daewoo-electronics.com (no reply)
daewoo@daewoo-electronics.it (no reply)
kimym2@web.dwe.co.kr (mail undeliverable)
info@dempol.com (mail undeliverable)
information@desuk.co.uk (mail undeliverable)
sk.yim@daewoo.a.se (mail undeliverable)
info@daewoo-electronics.nl (mail undeliverable)
service-conso@daewoo.fr (mail undeliverable)
info-hu@daewoo-electronics.com (mail undeliverable)
daewoo@iti.lt mail (mail undeliverable)
ioana@daewoo-electronics.ro (mail undeliverable)