English Amiga Board


Go Back   English Amiga Board > Support > support.Hardware

 
 
Thread Tools
Old 15 September 2003, 10:57   #1
manicx
Junior Member
manicx's Avatar
 
Join Date: Oct 2002
Location: Athens, Greece
Posts: 986
Unhappy Amiga 4000 Sound Problem

Okay guys, sad day for me. In the last few months, my Amiga 4000 was packed in the box due to lack of space in my wee flat. I was just taking it out when I wanted to do something with a real computer.

After a point I noticed some noise coming out of the speakers. In the beginning, this was very random and I always thought it may be the cheap speakers. On saturday, we had the Greek Championships in Kick Off 2 and my A4K was on for 7 hours. After a point the noise was constant and very disturbing. I decided to investigate the problem.

I noticed that the noise was also coming out through other speakers too of much higher quality. I took the mobo out, cleaned the sockets and the dust. Nothing, noise still there.

Here's what I hear:

http://users.hol.gr/~manicx/Downloads/noise.mp3

One thing that makes me feel suspicious is that I used to have an external scandoubler that was sqeezing the left audio port a bit. I am not sure if this noise is due to the dated RCA sockets. Sound is coming through the sound chip so I assume it is a problem with the output. I am not sure if this is due to RCAs or a capacitor.

Here's a picture of the right socket:



When I tried to insert a screwdriver in 1, I got the same noise. In 2, you see the CD audio output that mixes with the Amiga output. I took this off and noise is still there. The card you see on the top is a scan doubler and has a safe distance from everything else.

On a second test, I noticed that the noise is coming out from the left speaker. When I unplugged the left RCA socket, the noise passed to the right one. This is 80% certified test, I just leave 20% in doubt because I was a bit confused last night.

What do you think guys? Could this be a RCA socket problem? Is it a capacitor? Is it something else? What do you recommend me doing. I 'm feeling crap but I am prepared to fix that because I love my Amiga 4000. BTW, does anyone know where I can find the scematics of a Rev B A4000 motherboard. I found them only to (several) IFFs but I prefer a single image that I can print and take it to an electric engineer in case that my Amiga needs a surgery. Hope I didn't forget anything.
manicx is offline  
Old 15 September 2003, 14:03   #2
Severin
Registered User
Severin's Avatar
 
Join Date: Dec 2002
Location: Gloucester / UK
Posts: 700
Send a message via ICQ to Severin
Sounds like a dry capacitor to me, the 'unplug the left' test means nothing on an A4k, when only one lead is attached the output is automatically onverted to mono (for old monitors)....

now your mp3 has finished dl'ing.. it does sound like a capacitor...
Severin is offline  
Old 15 September 2003, 14:30   #3
manicx
Junior Member
manicx's Avatar
 
Join Date: Oct 2002
Location: Athens, Greece
Posts: 986
Thanks for your help. A friend of mine who is an electric engineer said that the most likely cause of this is a capacitor. I already made a cool picture of the scematics of A4k's audio. I am not sure though if the guy who is going to look after my mobo needs a full picture of the whole mobo or just the audio system. If anyone has a full image of the A4000 (Rev B) scematics, I would appreciate any help with it.

EDIT:

How safe is to do things with the A4k mobo? Is it safe to try to remove a capacitor (if it is a capacitor) or am I going to blew everything up?

Last edited by manicx; 15 September 2003 at 14:59.
manicx is offline  
Old 15 September 2003, 22:43   #4
Severin
Registered User
Severin's Avatar
 
Join Date: Dec 2002
Location: Gloucester / UK
Posts: 700
Send a message via ICQ to Severin
It shouldn't be too much of a problem as long as you have a decent soldering iron, 17w or thermostatically controlled to avoid excess heat dissipation through the MoBo, DON'T use a 15w iron, they just heat the MoBo up before the solder melts

Use a decent desolder tool, 'blob & bang' is not a good idea here
Severin is offline  
 


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Amiga 4000 Sound Distorted and low virge support.Hardware 28 15 July 2018 19:18
sound issues on Amiga 4000 sovietconscript support.Hardware 10 13 November 2012 15:07
AMIGA 500 - Sound Problem sebmacfly support.Hardware 35 18 June 2009 06:24
Strange sound problems (distortion once again) - Amiga 4000 viddi support.Hardware 6 10 February 2008 18:09
Amiga 4000 HD LED Problem CU_AMiGA support.Hardware 7 19 January 2007 02:35

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +2. The time now is 03:06.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Page generated in 0.06276 seconds with 13 queries