Hi,
 
Just a thought. I like silent computing and my Amiga 4000 has a power supply fan blowing air the wrong way. It's a known problem that quite a few A4000s are constructed this way, the fan is blowing hot air into the power supply and not out of the chassis.
 
Now, my questione is this: is it a very bad idea to just remove the fan completly? This A4000 is quite cold, the CPU is a 68060 (CyberStorm MK2) clocked at 50 Mhz. What risk would I be running? I guess the 68060 wouldn't overheat, but what about the power supply?

These old computers have enough trouble as it is, use a fan to move a little air atleast.

Get a near silent fan for a PC and just wire it in.  Some of them are 5v instead of 12v, so make sure before you wire it up.

I did this to mine when I put in a small atx power supply and it's effectively silent.

Hi,
 
Just a thought. I like silent computing and my Amiga 4000 has a power supply fan blowing air the wrong way.

Back when they came out, that was a big problem for people in some regions. I remember usenet posts from people in Australia that could not use their new A4000D's in the summer! If you are in Norway, could be a different situation. I know Sweden had to retrofit the coastal patrol submarines they exported to middle eastern countries to add air conditioning - they had never even thought about AC when using them off Sweden, they needed heating.

The stock A4000D ps CBM bought is junk, although many are still running. LoadWB is right - the only limitation is form factor, there is only so much room inside the case. I mounted my replacement -behind- the case, behind where the ps normally goes, and used a cantilever system to support it. This consists of, on top, two steel bolts with curved hooks on one end to catch the back of the ps, and the threads and nuts on the other tensioning (is that a word?) it unto the case. The ps fan still draws air through the case, and now I can use just about any supply I can find. I should post a picture.

Years ago, when I had too much time on my hands, I made my A4000D totally silent. I got a bunch of surplus Linear DC power supplies, one for each needed voltage, probably from old minicomputers. Each one was half as big as my A4000D, and twice (or more) as heavy, and I needed three (+5V, +12V, -12V). Put them on a shelf below and used automotive starter cable (big as your finger or thumb) to get the power to the motherboard. These supplies had big fins for passive cooling , no moving parts! Left the case off the Amy Was wonderful, but when time came to move, I could not take the beast of a setup  Went back to ATX setup described above.

I found the picture of my ATX PSU.

http://www.amiga.org/gallery/index.php?n=2720

One more question. The A4000 PSU fan has only two connectors, right? New fans have three: red, black and yellow (ground?). What to do with the last connection, just ignore it?

Thanks everybody for the help. I think the way to go is to replace my PSU fan. Just to get this right, this should be a 120 mm x 120 mm 12 V fan? You can easyly find fans like this that only do 15 dB!

The A4000D fan is an 80mm fan.  I bookmarked some really quiet fans at home, and will try to remember to post them here.  I found the fans in this very forum somewhere, after digging around for a few hours.

slaapliedje

I removed the fans in both of my A4000 PSU's (liteon and skynet) and replaced them with SWiF2-800's with rubber grommits which made them almost silent with "almost" the same CFM airflow as the original.

http://www.quietpc.com/cl-swif2-800

I was a bit worried that the airflow might be less with them being so much quieter but I've not had problems.

cool link still works for these quit fans:)

Back when they came out, that was a big problem for people in some regions. I remember usenet posts from people in Australia that could not use their new A4000D's in the summer! If you are in Norway, could be a different situation. I know Sweden had to retrofit the coastal patrol submarines they exported to middle eastern countries to add air conditioning - they had never even thought about AC when using them off Sweden, they needed heating.

The stock A4000D ps CBM bought is junk, although many are still running. LoadWB is right - the only limitation is form factor, there is only so much room inside the case. I mounted my replacement -behind- the case, behind where the ps normally goes, and used a cantilever system to support it. This consists of, on top, two steel bolts with curved hooks on one end to catch the back of the ps, and the threads and nuts on the other tensioning (is that a word?) it unto the case. The ps fan still draws air through the case, and now I can use just about any supply I can find. I should post a picture.

Years ago, when I had too much time on my hands, I made my A4000D totally silent. I got a bunch of surplus Linear DC power supplies, one for each needed voltage, probably from old minicomputers. Each one was half as big as my A4000D, and twice (or more) as heavy, and I needed three (+5V, +12V, -12V). Put them on a shelf below and used automotive starter cable (big as your finger or thumb) to get the power to the motherboard. These supplies had big fins for passive cooling , no moving parts! Left the case off the Amy Was wonderful, but when time came to move, I could not take the beast of a setup  Went back to ATX setup described above.

The stock 4k psu's are not junk, as a matter of fact they have the exact same switching topology as modern psu's and of AT ones of the day. I do prefer the skynets to the liteon versions(easier to recap at least) however, both work exactly the same way as any switching psu.The fast that most of these psu's made it 15-20 years is pretty amazing.  If you want to see junk go thru most of todays atx,itx etc. very poor caps, little to no filtering,high ripple and poor +5 regulation. this is so common now its not funny, even some of the so called name brand 80+ certified atx psu's bomb. put a high quality fan with more cfm than the stock one and most all problems go away.