PDA

View Full Version : OT-Laptop audio repair



BillH
07-28-2004, 11:37 PM
Well, I was getting ready for some Ham APRS stuff on the road, setting up my radios to work with my sound card using AGW packet engine, and I found out that my Microphone jack does not work!! Probably something I did today to it, perhaps some RF got into it. Looking at it, to fix it, looks like I would have to open up the entire laptop case, and hunt down some component I might of fried. It's probably a diode or something. The built in microphone still works. In the past, when you used the jack, it would turn off the built in mic, and it still does that.
However hooking up a mic or audio input from the radio to the mic port, A wierd thing happends. When it gets a signal, the audio flat lines. when there is no signal, theres tiny bit of noise. However sound recorder records blanks with it.
Im not sure if its even worth it, may damage something else trying to get to it, and its most likely SMT which I never had the pleasure of fixing before.

J Tiers
07-28-2004, 11:53 PM
<font face="Verdana, Arial" size="2">Originally posted by BillH:

Im not sure if its even worth it, may damage something else trying to get to it, and its most likely SMT which I never had the pleasure of fixing before.</font>

Count on it. Easier to replace the card, if it is separate from the main board. These days, much of that stuff is all on one or two chips anyhow.

A lot of my stuff these days is SMT, and I find it a nuisance to work on. To remove and replace a typical 40 lead chip is just not sensible without about a grand worth of equipment.

You can do it, if you HAVE to, and if you have a good magnifying glass or microscope, and small soldering iron. But the parts are not often that commonly available because hardly anyone fixes the cards.

If its an older card, you may have a better chance. More generic parts on it. Signal does not just go into a big chip.


[This message has been edited by J Tiers (edited 07-28-2004).]

darryl
07-29-2004, 12:39 AM
I wonder if the built-in mic signal is fed through the mic input jack- if so it would seem that the preamp is working. The problem could be a mechanical one right at the jack, like a broken pc join, or an internal break in the jack. Beyond that, like said above, replace the board if it's separate from the m/b.

Evan
07-29-2004, 01:48 AM
I go with what Darryl said. The audio system is likely built into the MB chipset, nothing to fix there. The jack or it's solder connections are the likely problem. The hardest part of fixing it may be just getting the case open. I hate those things and for the most part refuse to repair laptops at all.

zl1byz
07-29-2004, 01:54 AM
Hi BillH, sorry to hear your problem with the laptop. I would double check it isn't a cable/plug problem b4 delving into the laptop too fast. Wonder if you were using any line transformers to isolate radio from computer. Being a ham here also I have used computers around radios for years with many different sorts of interfaces, fortunately have never damaged anything yet. I have always tried to use optical coupling or transformers to isolate radio & computer. Have had a few tense moments though usually been a hook up problem or software. I haven't used the AGW packet engine although I hear it works very well. Check that the microphone input hasn't been muted etc. Wonder if your laptop has a line in, does it still work?

Good luck,

John ZL1BYZ

BillH
07-29-2004, 02:22 AM
Everything works except for that jack, I ckecked many times to see if the jack was muted, no go.
I must of had my laptop too close to the radio, even though it was an HT on low lower power. Very wierd thing happened, My laptop just shut down completely, and the green power light was sporatically flashing. I was on battery power at the time. It's a pitty I cant get this laptop to work with aprs unless I buy a TNC.
THe laptop battery did not die, it still had 94% power left...

nheng
07-29-2004, 08:13 AM
BillH, Like Evan says, it is probably the jack or solder problem.

Sometimes, you can also get lucky and find a reference design for the audio chip(set). Or a typical application circuit may be found in the data sheet for the chip if you can find one. These will frequently show any buffer amps, decoupling capacitors and related circuitry.

I've fixed a number of laptops including my own Dell Inspiron 5000 last week on which the LCD would intermittently go bright white until it finally stayed bright white. Examination of chip and connector feet showed tiny lines of black oxidation around some, indicating that the solder joint was about dead http://bbs.homeshopmachinist.net//eek.gif Some fresh solder flux here and there (and everywhere) and a hot air tool restored it. You can do the same with a normal soldering iron and flux ... just check for solder bridges afterwards. I've done repairs on fine pitch and built new stuff with fine pitch with a regular iron and flux.

Den

RobDee
07-29-2004, 09:40 AM
Yep! Put me on the list of broken pc jack connections. I've done several repairs.
While you're at it watch out for this one:
My friend came to me with his brand new Yaesu rig that suddenly died on the receive when he was adjusting the car antenna. I traced it down to static from brushing on the car seat before he touched the antenna. The static charge blew out the RF amp. So if you work on your antenna make sure you ground yourself first.
SMT. Well I'm using it on my portable designs now in places where I want a specific chip but the manufacturer doesn't make it in DIP or TO-92. 40 pin SMT or PLCC uuugh!
RobD

nheng
07-29-2004, 10:01 AM
RobD: I've soldered many fine pitch devices with a standard Weller (TCPT?? iron) tip. I can't stand their micro tips because they are a b-tch to tin and don't stay that way.

On fine pitch stuff, flood the row to be soldered with liquid flux brush or pen. Create a solder ball on the tip of your well-tinned iron. Start at one end, feed solder as you move to keep a moving ball.

Sort of like a mini wave solder system. Check for solder bridges carefully when done. The solder joints are just about equal to or better than the best commercial joints for obvious reasons (clean, hot, good flow).

I have hot air equipment but the iron works much better when an inner board layer or ground plane sucks the heat out of a connection.

I have an Icom W2-A which I hadn't used for about a year. When I picked it up, the PL tones were non-functional ... rig was almost new. Took out the tone decoder board and found the same thing I've found on notebooks, TVs, etc. Micro thin black lines around the foot of a device lead. Flux - solder - clean and it's as good as new http://bbs.homeshopmachinist.net//smile.gif

Den

J Tiers
07-29-2004, 12:43 PM
<font face="Verdana, Arial" size="2">Originally posted by nheng:
RobD: On fine pitch stuff, flood the row to be soldered with liquid flux brush or pen. Create a solder ball on the tip of your well-tinned iron. Start at one end, feed solder as you move to keep a moving ball.

Sort of like a mini wave solder system. Check for solder bridges carefully when done. The solder joints are just about equal to or better than the best commercial joints for obvious reasons (clean, hot, good flow).
Den</font>

Yep, that works. I usually use the solder paste, because we have it here, but same dif.

We have some 4 layer power boards with the layers heavy copper (unit handles 40A / 180V). The only way I was able to get the thru-hole high voltage power Mosfets off was to use a solder pot. That copper sucked all the heat away.

You can usually do almost anything, if you have to.

Of course check the jacks, but don't be surprised if the connection in question is almost inaccessible (dang SMT parts).

BillH
07-29-2004, 06:43 PM
Well, my audio is working again. I did so many things that I cant scientificly prove what it was. All things included wiping Win2k off the hard drive and reinstalling WinXP. Never had to open the case up. I think I was using the wrong port on my radio, however that wont explain why the microphone I had would not work with it last night.

RobDee
07-29-2004, 06:54 PM
nheng & jtiers,
Thanks for the info. I'll give the ideas a try.
Rob

nheng
07-29-2004, 08:03 PM
Rob: You're very welcome. Hope it helps.

BillH: Windows audio drivers for various chips have many options in them either enabled, disabled or conditional and also control levels for inputs, outputs by type of device (wave, mic, etc.).

Sounds like you've got the right pieces now http://bbs.homeshopmachinist.net//wink.gif

Den

BillH
07-29-2004, 11:11 PM
Den, when I had fedora core 2 linux on this laptop last week, I was overwhelemd by all the freaking audio options it gave to my audio chipset, dev folder for audio, must of been over 50 items in there.

Dr. Rob
07-30-2004, 05:43 AM
Largely clueless as to the technical jargon named above, I just wanted to sympathize with Bill. My sound doesn't work either. No explanation. (IBM ThinkPad)

Contrary to Bill though, it isn't fixed now. Oh well. Bill, congratulations and tell me if you hear anything good.

Doc.