Re: Emerson LC391EM3 - Constant High Pitch Sound

Thanks for the info and explanations! I found a 6.7uF SMD cap that is a little bigger physically, but was able to solder it in. All back together and ready for duty. Hopefully the difference in capacitance isn't going to be a problem...if so, should I just remove it and go without?

Ya'll are great!

Re: Emerson LC391EM3 - Constant High Pitch Sound

I fixed it! I found the service manual/schematic in another post for a different model, but same boards. Without that, it would have ended up in the trash. The problem was on the main board, specifically C3103 (a tiny surface mount capacitor near IC3008) was shorted. I found it by checking the resistances of the various power supplies (or rather their loads) and the P-ON-12V was 10 ohms. Pulled 2 other caps before finding the bad one.

I'm reposting the service manual in case anyone else is looking for it. ...

Re: Emerson LC391EM3 - Constant High Pitch Sound

Thanks neilc6. Unfortunately, my ps and main boards are different from those in that thread, so troubleshooting is tough, especially without a schematic. I did check resistance from the various power supplies to ground with the main board connected and disconnected. I did see low resistance (24 ohms) at the P-ON-12V when the main board was connected. Disconnected it was 200 ohms or higher, changing as the capacitor charged.

Re: Emerson LC391EM3 - Constant High Pitch Sound

I should mention that I pulled and checked all the parts that vinceroger69 mentioned and they all test fine.

Re: Emerson LC391EM3 - Constant High Pitch Sound

I have the same TV with the same whine when the main board is plugged in to the power supply. Did you ever find your problem? I see people on ebay that sell repair kits, one specifically for the whine and won't turn on. It includes what looks like 3 surface mount caps and is cheap enough to try, but I'm not even sure it is the main board or the power supply.