Damaged my motherboard - Page 1
Forum section: electronics / projects

author: gnif
author_rank: Unknown
timestamp: September 30, 2013, 02:42:46 am
content: Hi All,This Saturday just gone I had to supply audio equipment for a wedding reception and at last minute found that the microphone and pre-amp I was going to use was no longer available... so in a rush to get things working I decided to buy a balanced dynamic microphone from my local Jaycar and build a preamp (they had no kits, our Jaycar's stock is laughable). This all went well, used a couple of UA741's to unbalance and amplify the signal with adjustable gain to feed into the amplifier... but, during testing of some filter configurations I bridged a track and fed 14VDC directly into my on-board sound cards line input.The results... the sound card no longer detects when there is an cable connected... no errors from the drivers in windows or Linux., but no audio output. At this stage I think I will just throw a sound card into the PC, but I was wondering if there were anyone out there that has more of an idea on how the audio in/out is designed on a modern motherboard and if there is any simple things I might be able to do to recover this (sending the board in for RMA is not an option as it is both dishonest and I can not be without a working PC while I wait).Edit: There are no physical signs of damage, all the chips are in-tact and none of them seem to be even warm to the touch.

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 03:00:32 am
content: Quote from: gnif on September 30, 2013, 02:42:46 amWait, are you talking about line-in or line-out not working, or both?In case of line-out, most mobos usually have a header with a second line-out or headphone signal for the front panel. Have you tried this too?

author: gnif
author_rank: Unknown
timestamp: September 30, 2013, 03:02:15 am
content: Quote from: elgonzo on September 30, 2013, 03:00:32 amBoth have stopped working, but it was damaged via the line input, and it was via the front panel connector... had not thought to test the rear outputs, let me see if they are functional.Edit: Rear outputs are also non-functional.

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 03:17:30 am
content: Then, in all likelihood, the on-board soundchip or at least parts of it is goneSome sound chips allow it to remap signals to different jacks (in a somewhat limited way) via a software that usually is part of the driver package. While i don't really believe that it would help; if you have such a sound chip+software, you might very well spend the 5 minutes to try it...

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 03:18:06 am
content: You shouldn't be able to kill the sense, as it's never connected to external devices (it's an isolated switch in the jack).Possibly shorted the coupling caps out and blew the main IC.E: That is, of course, assuming they bothered with coupling caps...

author: gnif
author_rank: Unknown
timestamp: September 30, 2013, 03:22:46 am
content: Quote from: Monkeh on September 30, 2013, 03:18:06 amThe sense on modern boards is done in software with some assistance of the sound chip, it is rare to see a front panel jack with a switch in it these days.Quote from: Monkeh on September 30, 2013, 03:18:06 amI believe both, but not completely, as I would get heaps of driver init errors from the system, or the device would just not show up.oh well... I am just thankful the machine still runs, I will see about sourcing a decent sound card to install, good excuse to get some nice gear.

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 03:28:18 am
content: Quote from: gnif on September 30, 2013, 03:22:46 amNot that I've ever seen. HDA standard uses a physical switch and that's what every datasheet shows the use of.For example:ftp://207.232.93.28/pc/audio/ALC1150-CG_DataSheet_1.0.pdf

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 03:31:16 am
content: Quote from: Monkeh on September 30, 2013, 03:28:18 amYupp, the standard front panel connector on mobos also has pins assigned to the sense signal(s).But, AC97 cannot make use of sense signal... argh... better not to know this stuff@Monkeh, the NSA is asking for your ftp password

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 03:35:36 am
content: Quote from: elgonzo on September 30, 2013, 03:31:16 amAs if I'd have an FTP server, let alone one that deathly slow. Realtek are still in 1986. I guess they still have a problem with people downloading things.This may or may not work better:http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PNid=14&PFid=24&Level=4&Conn=3&DownTypeID=1&GetDown=true&Downloads=true

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 03:38:31 am
content: Quote from: Monkeh on September 30, 2013, 03:35:36 amThat one works better, thanks!

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 03:39:18 am
content: At least they publish datasheets (hell, they even acknowledge their chips exist, unlike some companies)..Quote from: gnif on September 30, 2013, 03:22:46 amSeparated analog and digital sections.QuoteIndeed. Don't get anything involving Creative or VIA.

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 03:43:05 am
content: Okay, just for clarification, i found a picture that displays HD-Audio and AC97 front panel signals side by side.AC97 front panels make no sense

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 03:43:43 am
content: How do they not make sense?

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 03:46:57 am
content: Somebody must have crossed it out

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 03:48:10 am
content: Crossed what out?Also, that pinout's wrong:http://www.intel.com/support/motherboards/desktop/sb/cs-015851.htm

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 04:03:12 am
content: Quote from: Monkeh on September 30, 2013, 03:48:10 amNah, i was just pulling your leg. I meant that where the HD-Audio connector has one of the sense signals, the respectiveAC97 pin is labeled "X".Quote from: Monkeh on September 30, 2013, 03:48:10 amYou are right. Pin 4 is incorrectly labeled as AVCC. You have excellent eyes

author: amyk
author_rank: Super Contributor
timestamp: September 30, 2013, 07:23:14 am
content: QuoteYou can change the audio chip (can probably find it on Alibaba or eBay) and coupling caps.Attached a schematic from a random mobo of the audio area -- the input is basically directly connected to the IC pin.

author: gnif
author_rank: Unknown
timestamp: September 30, 2013, 07:24:56 am
content: I was not saying that the controller does not support sense wires, I was saying that most cheap computer cases with front panel connectors do not have the physical switches inside the sockets and as such most sound cards these days can detect connected outputs by other means. If you look at the connection to the motherboard often the sense pin is just a short loop of wire into another pin.

author: Psi
author_rank: Super Contributor
timestamp: September 30, 2013, 08:21:21 am
content: Yeah, if i had to fix it i wouldn't think twice about replacing the IC.Sound chips are usually just TQFP or similar so soldering a new one on isn't hard if you have soldering experience.But, as you say, you could just leave it and use a PCIe soundcard which will likely produce better sound anyway.I guess it depends how much you value your time.

author: gnif
author_rank: Unknown
timestamp: September 30, 2013, 09:56:39 am
content: Quote from: Psi on September 30, 2013, 08:21:21 amYes, I will still have a crack at it, I am a bit OCD and it will bug the crap out of me to know it is partially broken. In the meantime I will just have to put up with thenew card I ordered.

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 03:03:32 pm
content: Oh, dear, not the ROG stuff..

author: Paul Price
author_rank: Super Contributor
timestamp: September 30, 2013, 03:11:33 pm
content: You could have bought a cheap PCI sound card for <10 $US that would have worked better than your original.

author: elgonzo
author_rank: Unknown
timestamp: September 30, 2013, 03:44:05 pm
content: Quote from: gnif on September 30, 2013, 09:56:39 amI hope you enjoyed spending moneyROG is gamer crap, seriously...

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 04:32:08 pm
content: Well, the hardware in them is good, if not as good as the other Xonar offerings. But then you get saddled with the daft remote control, and poor Linux support (nobody's buying one for them to work with).

author: gnif
author_rank: Unknown
timestamp: September 30, 2013, 09:54:56 pm
content: Quote from: Monkeh on September 30, 2013, 04:32:08 pmI run Linux predominantly and I also contribute to kernel drivers on occasion, so this is no big deal for me. I also use some high quality high impedance headphones, which the built in headphone amp wins me over for. And finally my PC is in a very unwelcome location to reach to, and the breakout for volume + headphone/mic plugin is a welcome addition.And, the deciding factor is that it was $80 new in box from a friend who was given it as a gift, and cant use it as he has a laptop.

author: Monkeh
author_rank: Super Contributor
timestamp: September 30, 2013, 10:26:04 pm
content: Oh, well, at that price..Go forth and get the CMI8888 driver functioning!