A4000 Audio Problem

[beller]

I agree with countzero, you've got caps about to fail.  

My A4000's sound was failing along with the failure of the par: port.  I sent it to JJ at Amiga Center France and he fixed both problems which were, apparently, related.  Working fine now and I had him put in a coin style battery too...

Bob

[da9000]

spaceman88 wrote:
I tried cooling Paula and some audio parts with freeze spray, but no effect.

You obviously know your stuff ;-)

It's weird, how it behaves, but the time-factor seems indicative of something to do with caps and/or inductors, but then again...

Anyways, I agree with Countzero on the full replacement of all SMDs, so here's what I got from jameco.com for replacing *all* A4000 (desktop models) SMD caps (please double-check in case I typed something wrong):

Code: [Select]


Description              Jameco#      Item#  Quantity
Cap,Tantalum,100uf,6.3V  TM100-VP-R   33702  1
Cap,Tantalum,47uf,16V    TM47/16-VP   94124  10
Cap,Tantalum,22uf,16V    TM22/16-VP   94095  5
Cap,Tantalum,10uf,35V    TM10-VP-R    33691  1
Cap,Tantalum,4.7uf,35V   TM4.7-VP     33807  1
Cap,Tantalum,4.7uf,25V   TM4.7/25-VP  94044  1


[Tension]

I can`t believe it!!

I have the exact same problem for the last 5 years with my A4000D!!! I haven`t been able to print a thing in years, plus my sound is crap, and sometimes the computer acts as though the right mouse button is stuck down.

I noticed that fiddling with the monitor cable / audio connectors seemed to help with the sound and mouse problem, but since my printer (which works fine on peecee) has been printing nonsence for so long, it def does sound like my CIA`s are screwed.

Where can i send the MoBo off for repair and how much would it cost?

[da9000]

@Tension:

read the entire thread, it might not be a CIA problem...

[Tension]

@da9000

But do the CIAs not control the Parallel port as well? Thus both problems could be coming from the same point of failure.

[da9000]

@Tension:

my point was that we've not entirely sure of the exact cause - all these things we've talked about are theories so far. It could be the CIAs, it could be a custom chip, it could be the leaking/dying SMD caps, dry solder joints or a combination thereof. Thus, I'd wait for the OPs results before jumping to conclusions.

[spaceman88]

@da9000

Thanks for all the info. I'm going to order the caps and scrub the board. Hopefully it will make a change in performance (for the better I mean :-)).

Len

[QuikSanz]

BTW, just checked. Still have a JPEG of the schematic for the audio if you need it.

Chris

[da9000]

@spaceman88:

No prob. Good luck with the project. BTW, if you're going to order from jameco.com or similar you might want to look at their catalogue, since they have so many goodies :-)  I've no personally tried to, but you might want to see if you can locate a plug similar to that used by the A4000 PSU, so that you can create your own PC PSU -> A4000 PSU hack, just in case the problem is with the power supply or for having a 2nd PSU for the future. Just a thought. I also picked up some Schotcky  diodes and coin-holder for doing the lithium battery hack.


QuikSanz: post a link, not sure which ones they are, but won't hurt to have'em around.