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WTB: Amiga 4000 motherboard

oblivion

oblivion

Veteran Member
Joined
Aug 28, 2010
Messages
1,003
Location
Apache Junction, AZ
I know this is a long shot but does anyone happen to have a working A4000 motherboard for sale? I don't need ram or any expansion cards or even the CPU daughterboard just the motherboard.

My motherboard has had sound issues and I've just sunk way to much into trying to correct the issue. Its to the point that Id just rather grab another MB to install as unlikely as find one will be. at least at a non insane price.
 
"Amiga 4000" and "non insane price" are 2 different things. In Germany these were quite popular so you got good chances here.

This auction is still "Under 250 Dollar", but personally I don't expect it to stay that way...

http://www.ebay.de/itm/Amiga-4000-D...145325?hash=item1c5fe852ad:g:6PMAAOSwKtlWm-mI


There is a "quite complete" set (minus scsi controller and keyboard) for 590 Euro... Nearly a "bargain" if you look at some crazy prices Amiga 4000 sold for...

http://www.ebay.de/itm/Amiga-4000-v...762889?hash=item5b1f46e189:g:zksAAOSwwPhWkXbX
 
kyodai said:
"Amiga 4000" and "non insane price" are 2 different things.
Click to expand...

+1! I was able to completely liquidate an Amiga 4000 system that was unworking and advertised it as such and it ended up well over $500. I probably could have got even more for it if I had accepted international bidders, but didn't want to take the chance on such a spendy item.

The prices on pretty much all the various Amiga models in the US are pretty expensive these days. I keep thinking I'd like to get an Amiga 1000 again (I've had three in the past) but I think I've been priced out.
 
Trixter said:
Funny, the MB I was going to offer you also has a sound issue. Sound in one channel is "fuzzy". We replaced some of the surface-mount capacitors but it didn't help.
Click to expand...

when I first got the machine the sound was extremely low and one channel went in and out. I had the board recapped and then whenever the machine was on I got a constant high pitched screeching sound. so then we figured maybe the caps used for the sound were not the correct one but even after replacing those with the origional type I still have the screeching...except on the guitare intro to elite plus...i just cant figure it out and i'm just tired of mailing it back and forth to people.

when you say fuzzy what do you mean?

heres an example of what it does. word of advice, turn your volume down before clicking. skip to :36 to see what I mean about Elite.

https://www.youtube.com/watch?v=8-o2GgpLC_A
 
oblivion said:
when you say fuzzy what do you mean?
Click to expand...

One channel sounds slightly muted and distorted. Since I needed it for a video capture project, that was unacceptable, so I got a rev c board to replace it. THAT board we couldn't use either because you can't use '060 accelerators with a rev c board (something about the timing crystal being on the board instead of the processor card). So I am the "proud" owner of two A4000s and two additional A4000 motherboards.

heres an example of what it does. word of advice, turn your volume down before clicking. skip to :36 to see what I mean about Elite.
Click to expand...

I can't comment on how to fix it, but it sounds/feels like the Paula is getting garbage information all the time, until you need to play a sound and then it stops. Very odd behavior.

gary2000 said:
What would the motherboard with sound issues go for? Mine is totally dead.
Click to expand...

I have no idea. The prices of Amiga gear are nutty and I have a lot of Amiga stuff that I want to go to good homes but I also don't want to get taken. ebay, international shipping, amibay? Single lot or piece it out? The prospect is so daunting that I usually give up after half an hour of research.
 
Its very likely other issues in the audio section besides the caps. The electrolyte has done more damage than one can visibly see. This guy did an advanced diagnoses and repair on a A4000 with audio problems that might help (he has other Amiga model repair videos too):
https://www.youtube.com/watch?v=Bc5HRF7zjiA
https://www.youtube.com/watch?v=3Y8VbfdwjXY

Chances are the other broken boards out there have the same problem. I got lucky and a simple recap brought the audio output on my board back to life.
 
njroadfan said:
Its very likely other issues in the audio section besides the caps. The electrolyte has done more damage than one can visibly see. This guy did an advanced diagnoses and repair on a A4000 with audio problems that might help (he has other Amiga model repair videos too):
https://www.youtube.com/watch?v=Bc5HRF7zjiA
https://www.youtube.com/watch?v=3Y8VbfdwjXY

Chances are the other broken boards out there have the same problem. I got lucky and a simple recap brought the audio output on my board back to life.
Click to expand...


If electrolyte or battery acid did damage or just "touch" the board then the first thing i would recommend (If no other visible or obvious problems can be located) is a short bath in dilluted formic acid, followed by denatured alcohol. Splattered electrolyte and battery acid can have funny results on electronics, some circuits are so close together that all kinds of residue and oxidation problems can be a problem, some smudge you can't even see but it changes the resistance of the circuits considerably. If i have no other components to suspect i use a warm bath with dilluted formic acid (around 3% is fine) for about 40 seconds, that eats away all oxydation products. Then put in 90% alcohol bath to get rid of the water and dissolve remaining smudge in alcohol. Carefully dry with a hair dryer. You would be surprised how many problems that seem impossible to explain can be fixed that way. At least if recapping didn't help and you run out of ideas then i would recommend this method.
 
kyodai said:
If electrolyte or battery acid did damage or just "touch" the board then the first thing i would recommend (If no other visible or obvious problems can be located) is a short bath in dilluted formic acid, followed by denatured alcohol. Splattered electrolyte and battery acid can have funny results on electronics, some circuits are so close together that all kinds of residue and oxidation problems can be a problem, some smudge you can't even see but it changes the resistance of the circuits considerably. If i have no other components to suspect i use a warm bath with dilluted formic acid (around 3% is fine) for about 40 seconds, that eats away all oxydation products. Then put in 90% alcohol bath to get rid of the water and dissolve remaining smudge in alcohol. Carefully dry with a hair dryer. You would be surprised how many problems that seem impossible to explain can be fixed that way. At least if recapping didn't help and you run out of ideas then i would recommend this method.
Click to expand...

hmm, thanks for the tip. maybe I'll give this board another go.
 
oblivion said:
hmm, thanks for the tip. maybe I'll give this board another go.
Click to expand...


On a side-note - if you can't get formic acid then vinegar will also do. I prefer formic acid as it contains less unwanted chemicals since vinegar is usually made naturally. But some white vinegar are quite clean regarding other unwanted organic substances. And the poor mans solution would probably replace the medical rubbing alcohol with Vodka. Just be sure to dry it really well and not too hot.
 
Out of curiosity, I normally use Scrubbing Bubbles - which is ammonia based - to eat away at corrosion and oxidation. Any thoughts on the comparison, or are we taking about totally different purposes?
 
raoulduke said:
Out of curiosity, I normally use Scrubbing Bubbles - which is ammonia based - to eat away at corrosion and oxidation. Any thoughts on the comparison, or are we taking about totally different purposes?
Click to expand...

From a chemical point alkali (like ammonia) are not suitable to dissolve oxidation products like rust. It is a good general cleaning agent as it will dissolve some types of smudge, but chemically speaking any alkali based formula would not defeat oxidation products.
 
I think for Amiga 4000 the vintage world is a bit upside down. There are just loads of people who don't care about how mint or original a system is, they just want a "maxed out" working system. I have seen so many "pimped" Amiga 4000 thatsold for much more than a machine in it's original state. I never understood why people would spend more than a grand for a 25 MHz computer for "using it". As much as I'd like to toy around with Amiga OS 3 or 4 I wouldn't spend so much for it. Well i probably would if there was a portable version with a monochrome screen. XD

To me it stopped losing fascination with the demise of Commodore, I can't help but feel that AmigaOS and Kickstarter developed more into mooching off nostalgic people. Especially the agressive hunting of "Abandonware" sites that had the Kickstart 1.3 ROM for download was ridiculous, even today they try to sell a nearly 30 years old ROM for like 10 dollars.

I ain't even gonna bitch about AmigaOne and other hardware. It's actually a nice System and AmigaOS 4.1 - sure a fun system and fun hardware, but to buy a rather obscure system that costs like 2500 Dollars in a configuration that reminds you more of a 300 dollar bargain PC from a department store 5 years ago? I still have my original Amiga 500 from the 1980s, but Amiga nerds of today? They are crazy AND rich if you ask me. Soooo if you look at the AmigaOne then the recapped 4000 board actually looks like a bargain. Depending on the point of view...
 
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