Isolation of headphone plug on circuit board - Page 1
Forum section: electronics / projects

author: Velkozsolomid
author_rank: Newbie
timestamp: June 26, 2014, 10:42:22 pm
content: So I have this LCD screen with some crappy built in speakers but there is a 3.5mm jack that is an audio in. This screen has no audio out plug so hdmi inputs come out of the crappy baby speakers. I found the 3 spots that the jack is soldered to the board with and I was planning on isolating them from their original circuit cause if I soldered audio out speaker wires to them it would be a feedback loop if I'm not mistaken. I planned on just scraping away the trails on the surface of the board, for the left and right channel it's easy enough but the ground connection continues on to another part of the board. I was wondering if I can isolate the whole spot or if I have to leave that pathway intact. I'm imagining I have to. Since this is my computers screen I am on my iPad taking the pics and editing them and uploading them so here is a link to a pic of what I'm talking about.HTTPS://www.dropbox.com/s/29u5843yrw9xlrn/2014-06-26%2015.30.24.jpgI hope that works.With that picture, can I scrape out the circuits path on the yellow lines or do I need to leave it intact and isolate with the blue line.This is all really just to have a neater setup and no wires hanging out soldered to a free hanging headphone jack that I would then plug a headphone cable into that leads to my sound system.And on top of all that does it seem safe to do that at all. And by that I mean redirecting wires from one spot to another. I had confidence but I'd rather not mess up my LCD.It is an acer h233h 24" widescreen LCD. Any feedback would be awesome.Love this website and all of Dave's videos. He's very inspiring and makes me want to make stuff and put my oscilloscope to use.P.s. Oh yea. It is a one sided circuit board for where the audio in port is soldered.P.p.s. I tested link, didn't work, this shouldhttps://www.dropbox.com/s/29u5843yrw9xlrn/2014-06-26%2015.30.24.jpg

author: mariush
author_rank: Super Contributor
timestamp: June 26, 2014, 10:55:41 pm
content: You can try to solder a headphone jack there and see.You could also just try to see if there's some signal by using a multimeter.There's a small chance that the headphone output is a separate audio amplifier output which is only enabled by the firmware, and the firmware of your monitor may not have that feature.later edit: ah, i didn't read it properly. I assumed that's missing headphones jack but I think you're saying that's the input jack footprint. If that's the case, yes, you could just scrape off the "paint" to the left of those surface mount components and CUT the copper layer to separate the jack from the rest of the circuit. you can then solder wires to those ceramic capacitor terminations.

author: Velkozsolomid
author_rank: Newbie
timestamp: June 26, 2014, 11:04:51 pm
content: Ah cool cool, yea that's what I was wondering.good to know. And Ty for the quick reply. I'm gonna try to go for the cleaner look and use that plug.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: June 26, 2014, 11:47:56 pm
content: you could use a dvi - dvi cable instead, as dvi doesnt carry audio.Then just conect audio out of your pc to your sound system .

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 27, 2014, 12:48:59 am
content: You could disable the built in speakers and then use S/PDIF to a digital amplifier.

author: Velkozsolomid
author_rank: Newbie
timestamp: June 27, 2014, 02:06:33 am
content: i do have a dvi cable from my pc to my screen but when i want to play my ps3 in my room it has to go by hdmi. and unfortunately unless im super blind, i dont think it has s/pdif outs. no sarcasm rudeness intended but i am super blind when looking for things a lot of times.(tangent) when i was younger i always swore LEGO company left pieces out of sets cause id be looking for a part for like 10 minutes in a pile of not that many legos.anyways. i was able to isolate the pins of the headphone jack that was being used as audio in and hooked up the speaker wires to them. plugged it all in and it was super fuzzy and the audio would go in and out in sort of a square wave fashion. like, the audio would be muted and then make noise at about 3-6 times a second. i thought it may have been cause i was sharing the ground for the left and right channel but that was not it, then i soldered the wires to a standalone jack that i had lying around, same problem. but it got even weirder. i have that leading to an input in my 16vlz3 mixing board and without the audio routed to any output there was noise coming out of the speakers. i was totally weirded out cause it made no sense. also 2 channels that my pc uses were showing signs of input that matched what was coming from the ps3 but my pc wasnt on and nothing else was leading into those channels. and i feel like i know my way around my mixing board enough but i couldnt make sense of why that was happening. im guessing maybe cause everything is on the same power strip and hooked up between each other but i dont know for sure. maybe ill draw up a diagram to show how everything is hooked up.i eventually hooked up one of the crap speakers from the screen back to the wires they were originally hooked up to and they still have the stuttering problem so i made a problem where there wasnt one. oh well. untill i have more diagnostic skill to find out why its doing this now ill have to play ps3 downstairs since theres no normal audio that i can use.so for now, pc games it is.ty again everyone for the replies.

author: Monkeh
author_rank: Super Contributor
timestamp: June 27, 2014, 02:16:37 am
content: Your PS3 can output line level audio from the old style AV output alongside HDMI video. Use that.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 27, 2014, 02:20:26 am
content: You can also use a HDMI audio splitter to pass the image through but provide S/PDIF to the amplifier.

author: Monkeh
author_rank: Super Contributor
timestamp: June 27, 2014, 02:21:52 am
content: Quote from: NiHaoMike on June 27, 2014, 02:20:26 amAssuming he has an amp with S/PDIF input.. the PS3 has dedicated optical S/PDIF output, too.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: June 27, 2014, 02:30:54 am
content: Could also use a dvi splitter with a dvi/hdmi adapter for the ps3 end and an rca or spdif splitter for audio

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 27, 2014, 06:35:59 am
content: Quote from: Velkozsolomid on June 26, 2014, 10:42:22 pmHuh? Do you mean that you identified the location of the power amp output inside the LCD screen so you could connect it to better speakers?Else I am not following what you are trying to say. Not really clear what is the SOURCE of the video/audio. (i.e. where does the OTHER end of the HDMI cable plug into?) Doesn't the source device (computer? game? cable box?) have an audio output in addition to HDMI?Google reveals that nobody else has figured out how to do this either. That LCD screen is apparently not very audio friendly. Get your audio directly from the source and bypass the crummy audio in the screen. I don't see any audio jack, input OR output....

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: June 27, 2014, 08:09:51 am
content: This pic shows all the connections on the monitor .http://www.runaroundtech.com/wp-content/uploads/2011/02/IMG_1451.jpg

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 27, 2014, 12:27:02 pm
content: Quote from: fluxcapacitor on June 27, 2014, 08:09:51 amBut the question is: Does that audio input work when the monitor is using HDMI in?

author: Velkozsolomid
author_rank: Newbie
timestamp: June 28, 2014, 12:54:56 am
content: Yeah I Was trying to redirect the speaker output to the now isolated audio in jack.I scraped off the copper trails that connected the audio in to the rest of the board and hooked the speaker wires to it. It worked but the audio was coming out weird.The source of audio was a hdmi from my ps3.Good idea from monkey, totally forgot I could use that av ps3 cable for audio and hdmi just for the video.Quote from: Monkeh on June 27, 2014, 02:16:37 am