No Sound from my A4000, it just quit!

[DegeRandolf]

Hi,
Trying to troubleshoot my A4000 sound problem.  I have a cdrom drive hooked up to the cdrom sound out connector of my Picasso and I can hear that play just fine.  But just lately I can't hear any sounds generated by the Amiga.  I've tried booting with a floppy to by-pass any software related issues but it's a no go on the sound.  
So here are the steps I've taken:
1.  Verified the speakers and cable used to connect them work.
2.  Verified cdrom music from the Picasso IV audio out
3.  Booted up Battlechess to bypass software installed on harddrive.  No sound.
4.  Using Amp from OS3.9 I can see the sound sample playing in the equalizer and volume is all the way up but no sound.

So what's next?  Is it time to open it up and start pulling boards out, re-seating chips, tracing solder joints?  Any informed guesses?  Helpful suggestions?  Okay, I'll take smart ass comments if it helps me solve this

[Castellen]

As mentioned many times in other discussions, it's a common problem for A4000 audio to fail due to the SMD 22µF electrolytic capacitors in the audio output stage leaking electrolyte, so this would be the first thing to check.
The same goes for various other 22µF electrolytics on the board.  I think there are around 5 in total on the A4000D, which should all be replaced if any leaking is suspected.

I won't go in to the details of it, but do a search in the forums and you'll find it mentioned a fair bit, and how to fix the problem.

[DegeRandolf]

Thanks for the info.  I did a search of the forums but didn't see this mentioned anywhere.  The thing is I just put this board in just a few days ago.  It was a refurbished board from Software Hut.  I had to return the first one as it wouldn't boot.  Just a cold fish.  This one seemed to be working fine until the audio quit.

[DegeRandolf]

Okay, problem solved.  Sort of.  I found that if I remove the cdrom connector to the picasso IV my sound came back.  
Now to figure out why that is.....

[billchase]

Have you double-checked that you are plugging the
CD-ROM cable on the correct pins?  Also,
there is a program that switches between the
PIV various sound inputs.  It is possible that
the sound program saves its settings directly
in the PIV.  I will have to check my setup out
when I get home and I will get back to you.

C Snyder

[Castellen]

One of the discussions on capacitor problems is here:
http://www.amiga.org/forums/showthread.php?t=5667

If using any of the advice, read all the posts, as there is some potentially bad advice in the web links given at the start.  I.E. removing SMD capacitors by "twisting" them off the PCB!


The audio problems may be caused by your CDrom audio having a low output impedance, which is connected to the high impedance internal audio connector which is probably about 10k or more.  The low impedance output loads down the high impedance audio.
You can help the problem by building an impedance matching network.


Another possibility is the audio connector pin configuration. From memory the one on the Picasso IV is a 3 pin header, with ground on the center and L&R audio on either side.  Like L-G-R.
Some audio connectors are 4 pins and are arranged like this: L-G-G-R.
So if you were to plug this into your 3 way header, it would effectively short one audio channel to ground.


Also as mentioned there is the Picasso IV audio switching program, but it's more likely to cause no CDrom audio output if set up wrong.
The program comes on the driver disks, and is usually copied to SYS:WBstartup during installation.  It's probably run as a commodity, so use Exchange to make it pop up.

[DegeRandolf]

I had to rewire the cdrom wire to three pin AND use the switching program.  All is working correctly.  I sure didn't want to tackle the replacement of capacitors and the like.