# proscan 40ld45q power issue



## joeman540

I just picked up a 40 inch proscan LCD, it will turn on for a second and show the full screen then switch off, the light on the front is red when off, then turns green when i power the set, then turns red as it shuts off, i pulled the LCD apart and took the power board out, i replaced all the caps on the power board just for good measure and it is still doing the exact same thing, any general advice about where else to look would be appreciated, i read something about a flyback transformer that can go bad?? i also read something about a transistor that likes to go out. if i bought a whole new tested good power board for the tv would this problem go away or just burn money out of my wallet??

again any info would be appreciated, i have everything as far as test equipment so fire away any suggestions for testing!!

thanks


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## lcaillo

LCD sets have no flyback. The first thing to do is to make some measurements to see what is powered and what is not. You have to have some basic idea of how the set works to do so. Getting a service manual or schematic may help if it is available.


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## joeman540

I thought flybacks were for older style tvs i was not sure though, you wouldn't happen to know where i could locate a service manual i have been digging for a few hours now and i have come up with nothing, i just tried emailing on corp but i doubt they will give me any useful information, i tried googleing for quite awhile and nothing has really been useful or informative about locating one


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## joeman540

-what on corp sent me lolz-

"Dear Mr. .....,

Thank you for contacting Online Support. We are sorry to hear the TV is not working properly. I do apologize, but I do not have a repair manual for this TV. A&E is the company we contract with for the warranty repair of our TV’s. You can give them a call at 1-888-977-6722. Select option 2 for troubleshooting or to arrange for service repair. Please have the serial number, location and date of purchase ready for the technician.

Please note that if the TV was purchased within the last 12 months then the warranty should still be valid. If the purchase was made over 12 months ago then costs for parts and repair may apply. Thank you.

Regards,"

at least they got back to me :sn:

update note:
i took the TV apart again and am now checking various things with my multi meter, i will report back later what i find


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## lcaillo

None of my sources seem to have it, which is not surprising. The only support this company provides is basically warranty replacement. If you do not have the skills to troubleshoot you are left with guesses about which board to replace, and you may not even be able to get the boards. Best bet there is ShopJimmy. These sets are designed to be disposable...


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## joeman540

update:

i replaced all of the capacitors highlighted in yellow, i figured i would upload a few shots to maybe help anyone trying to help me

i do not see any visibly blown caps, no scorching on the board from something that may have burned out, the LCD starts and the screen comes on but then shuts off right away, i have tested everything i can think of with my multi meter and I'm not seeing anything wrong, I'm still leaning towards something being wrong with the ps board but I'm not sure, since i replaced the cluster of caps that tend to go out on this board, I'm running out of ideas as far as my tech knowledge goes, i think i may just try tracking down a new ps board there's tons of them on the internet.. would this be a bad move since i cant track the problem down? i wanna see this lcd come back to life but i don't wanna waste money either




























any helps appreciated!


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## lcaillo

Are there labels on the board that identify the output voltages for the power supply? Does the picture look normal? Do you get sound?


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## joeman540

it only powers for about a second then switches off, the input screen that it goes to when on for that second looks fine, back lighting looks to be working, no sound as far as i can tell, the tv switches off to quickly


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## joeman540

this is all i could find on the board, there is a lot of identifiers listed on the back of the ps but im sure those are just location markers for the schematic i cant find.


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## lcaillo

Is there a connector labeled 35F or 2F?


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## joeman540

i found one called pc2f, im looking i cant seem to find either of those you mentioned by themselfs, i also found a cy2f that looks like a disk cap, a L2f, cx2f, and a c35f which also appears to be a disk cap


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## joeman540

just found con2f the pic i listed that has the box with all the info in it is for con2f, im assuming this is the one you were talking about


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## lcaillo

It looks like a map of a connector to me. There should be a connector with those voltages on the pins.


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## joeman540

this is con2f


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## joeman540

i disconnected the speakers and tried booting the tv, it tuns on and stays on with the speakers disconnected.. what does this mean?


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## joeman540

nice now i just need to figure out whats wrong with the audio


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## lcaillo

Looks like it is a map to the voltages on that connector.

My guess is a short in the audio output stage. Measure the voltage between each connection to the speaker and ground. You may find supply votage on the output. If so, you have a bad output IC.


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## joeman540

yep you were right it was a bad output ic, i just ordered a new one, i really appreciate the help lcaillo, its people like you who make going on forums like this worth while, i will be sticking around and i will try to help others and do what I can, I am a computer technician by trade so anyone with any computer/networking issues feel free to get at me


thanks again


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## king1199

Good evening everyone, 

I'm having the same issues on my Proscan, It shut off 2 months ago and never turned on. I got a use Power supply from ebay and swapped it and still did not turn on.. Can it be something else wrong with this TV? Please help.. Thank you in advance..


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## lcaillo

Check the related parts and for bad solder connections. There are often related parts that get damaged on failure or something that caused the failure to start with. You don't want to blow a new output device.


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