help my amiga 4000 has little or no sound output

[SilvrDrgn]

@ Darmaster70,

octamed my sound is crackly and very low in volume

By chance, have you had or still have an internal CD-ROM audio cable connected to the internal audio connector on the motherboard??  If you acquired the computer second hand, it's possible that the previous owner had the connection made.  I found that when I connected mine to my CD-ROM drive, the native Amiga audio did exactly what you're describing.  Unfortunately, when I removed the cable, the problem still happens.  Apparently, there is a fix for it, but it involves soldering of some sort on the motherboard.  I have not been able to find the details for it.

Could someone please let me know where to find such audio fix documentation

[SilvrDrgn]

Did you acquire the machine used???  If so, a previous owner could have had it connected and caused the problem.  Still looking for the motherboard fix .... anyone

[SilvrDrgn]

O.K.  Back to this problem again - especially when it is caused by connecting the internal audio cable from a CD-ROM drive to the A4000 motherboard internal audio mixer connection.  I have since disconnected the cable, but my A4000 still has little to no output and it always produces static/noise through the speakers regardless if anything is actually trying to play.

So, where can I find documentation on how to fix this problem??  Or who/where, in the U.S., can fix this for me???

[SilvrDrgn]

I get no colors at all during bootup.

[SilvrDrgn]

@ zeewolf,
I will have a look at my A4000 motherboard when I get a chance.  Thank you for the information.

[SilvrDrgn]

@ zeewolf,

there is on the net an Hardware hack explaining how to repair this problem

I've been looking for it, but cannot find it.  Where is it please - URL

(I'd love a sound card, but am saving cash for an AmigaOne system.)

[SilvrDrgn]

Over the Christmas holiday, I took my A4000T to my dealer in St. Paul, Minnesota (Raymond Computer).  We hooked everything up so I could let him hear the problem.  Unfortunately, he was pretty busy that day, so the only thing we were able to do for testing stuff on the motherboard was use his Advanced Amiga Analyzer package.  Plugged in the port dongles which have LEDs on them for checking certain pins.  Powered up and discovered that the +12 volt supply is not present on any of the ports that it's supposed to be.  That supply, along with the -12 supply, also powers the op-amp chips that produce sound from the motherboard.  Obviously, without it being there will produce the lack of or very low sound output.  Thankfully, that +12 supply for the ports and the sound is on an isolated circuit.  So, he thinks likely a fuse is blown or a trace is burnt out somehow.  We'll be investigating that later.

[SilvrDrgn]

@ Darmaster70,
You're welcome.  As far as Ray being close to me, he's not really.  It's a six hour drive.  Only reason I went there was because I was already visiting my parents for the holidays.  They live much closer to Ray's store (only 1.5 hours drive time).

Currently, Ray is looking for a replacement A4000D motherboard for me.  When he finds one, I will get that from him and he will get my current one with the sound problem.  That way I can keep using my computer, and he can further investigate the problem.  I will keep you informed on the progress.

[SilvrDrgn]

This exact problem was fixed on my A4000D motherboard over the weekend!!  The capacitors on my board have been replaced by the non-polarized type.  However, upon putting everything back together, the sound on my A4000 was still terrible (the same as it was prior to the capacitor replacement).  After 7.5 hours of messing around with the hardware (different motherboard, accelerator, removing expansion cards, removing Zorro expansion daughter board), my dealer and I found the problem with the help of his son's girlfriend (she works on electronic stuff all the time).  It was as simple as the -12 volt and its associated ground wire not making proper contact in the main 6-pin motherboard power connector. Prior to the capacitor change, I had done some other work on my A4000T.  In the process of putting it back together after that work, the -12 volt line and its associated ground wire got pushed out of the connector somehow so they weren't making good contact in the main power connector for the motherboard.  The op-amps (operational amplifiers) that produce sound on the Amiga require both +12 volt and -12 volt lines and their associated grounds in order to function properly.  Without either one, the sound output is very bad because they are unable to generate full waveforms.  We connected the main power connector and then wiggled and pushed in all of the wires with a pair of needle-nosed pliers.  After that, perfect sound from my system!