Repairing motherboard audio

Yes, low capacitance (and high ESR) can happen with no visible signs of damage. In fact that is the normal failure mode.

It is rare that there is no audio output, it is often really, really quiet.

It can be difficult to measure capacitance with the capacitors still in the circuit board.

If I have understood correctly what is going on, that is a 20+ year old PC. My suggestion would be to change all the electrolytic capacitors. The cost of the capacitors is so small that it does not seem worth trying to remove them to measure them. You may find it safer for the motherboard to cut the capacitors so that the legs are separate and you can then unsolder the legs one at a time. All new capacitors must be the right way round, and should be the same capacitance (although larger would most likely be fine). The voltage rating must be at least as big as the originals, but you can go for larger voltages if you want. The temperature rating should be as high as you can find, preferably higher than the original ones, as the higher temperature ones will last longer.

Thanks for your reply. I got this board around 3 years back and the onboard audio wasn't working ever since. I did try testing the continuity between the line out pins and the line out socket, but was getting the beeps only with the ground pins on the IC. I am confused if it could mean a defective one. Any other possibility to check the cause? Attached is the datasheet.

It could be a Microsoft driver problem - see this article:


Otherwise:
I'd do some more basic testing before replacing audio components.

Use headphones, not speakers.

Are the power voltages correct at the IC?

Do the drivers show any errors in device manager?

If you have something with an S/PDIF input, connect that & see if you get audio? (Or look at the S/PDIF connector with a scope?)

Install an old 32 bit version of Audacity, set something else playing audio and see if you can record back from the audio system?

These two do not involve any analog parts, just the IC & bus connections to it.

Try plugging in a mic and seeing if you can record that?

Keep trying different progressive tests that target different parts, rather than only trying to play audio, in other words.

Try a USB linux.mint live boot, see if still dead sound ?

rjenkinsgb said:

It could be a Microsoft driver problem - see this article:

Windows XP SP3 and Microsoft HD Audio UAA Problems (Update 3)

a blog about fixing computing issues, both desktop and server alike

www.boredsysadmin.com

Otherwise:
I'd do some more basic testing before replacing audio components.

Use headphones, not speakers.

Are the power voltages correct at the IC?

Do the drivers show any errors in device manager?

If you have something with an S/PDIF input, connect that & see if you get audio? (Or look at the S/PDIF connector with a scope?)

Install an old 32 bit version of Audacity, set something else playing audio and see if you can record back from the audio system?

These two do not involve any analog parts, just the IC & bus connections to it.

Try plugging in a mic and seeing if you can record that?

Keep trying different progressive tests that target different parts, rather than only trying to play audio, in other words.

Click to expand...

I actually had tried every available driver out there for Win 98, but to no avail. So installed XP which should automatically install the required drivers. However, still in vain. There is no sound in DOS either which is a major red flag. In addition, had given the board to a repair center which in turn confirmed that there is a hardware issue (they are not sure what though) and refused to do any further repairs (possibly fear of more damage).

In Win 98, there is absolutely no error message in the device manager nor the Multimedia icon. The installed drivers are displayed as it should be in a proper working sound scenario with the only exception of no sound. Haven't used headphones though.

I measured the voltage at Vcc pin on the ic and it was showing 5V. Then tried measuring the output from the Line out pin and the socket pin, but was only getting a feedback on the speakers. Had measured the continuity and it was only working with the ground pins on the ic. I was also wondering if the codec ic failure (VT1612A) would cause the drivers to install normally, but not actually work.