Fan replacement amiga 2000

[Elahrairah]

Hi guys and girls

So I did a fan replacement on my old Amiga 2000, noctua fan, the one recommended, 12v Noctua NF-A8 ULN. I did the wiring and when I test it the fan spins, low noise, perfect.
But when I connect the motherboard to the power supply the Amiga boots for a few seconds and then stops. No picture, nothing. All cards (I don't haved any) and floppy are removed.
Tried the old fan and everything works again. Amiga boots and works fine.
What am I doing wrong?
Also maybe good to mention the metasl psu cover has small (ventilation?) holes. It's not like the Amiga 2000 psu I've seen online. Maybe this type of psu doesn't support it?

edit: I just realized that this post probably should be in the Mod section. Sorry guys! I will move it to the mods section. Moderators you can remove this post.

[Malakie]

Just noticed your post being I had the same exact problem. Some A2000 power supplies (cannot remember make or model name) monitor the fan draw power level. I replaced my fan with the same identical fan you did, and poof.. same result.. powers on then just shuts down. Replacing the old fan makes it work again.

I came here hoping someone might have a solution for the A2000 power supply to fool it into thinking the fan is pulling enough power so it does not shut down.

If anyone else reads this and happens to know, it would be a great bit of information for everyone.

While I have worked extensively on Amiga boards and parts, I never really dug into the power supplies themselves. Until now. If someone has the schematics or knows how we might be able to fool the power supply into thinking the new fan is drawing enough power to be on, would be a great help!

For now, I will go back to the old, noisy vibrating fan.. which is a bummer since I will then have to pull this thing apart again.

[atalante]

I suppose some kind of resistor could help. Did You tried to connect fan via low noise adapter that was with noctua?

[Malakie]

Originally Posted by atalante

I suppose some kind of resistor could help. Did You tried to connect fan via low noise adapter that was with noctua?

Adapter? It came with was the fan, screws, rubber mounts and the 3 wire connection as well as the low noise wire connector. Using the low noise wire would have drawn even less power, which is the problem.

The Noctua fan is 12v but only pulls .6 watts and .05 amps of power. The power supply trips under .08 amps (forgot what the watts was). So to get around it, I installed a second identical noctua fan to the same connector and have that mounted blowing across the processer unit and custom chips even though they don't really need it. The combined pull of the two fans is enough to keep the power supply happy.

I have another system I am restoring with the same power supply only for that unit, I replaced the fan with another noctua but instead of a second fan, I am actually adding a couple 12v blue LEDs internally to backlight the drives and one 12v white LED with a toggle switch internal so if the case is open and the machine powered on, it lights up the internals to help see things a bit. That also was enough draw to keep that power supply running. This machine I am keeping, not restoring for someone else.

A 3rd A2000 I am restoring I plan on adding LEDs again only I am going to set them so they backlight the front bezel of the case depending on what is happening on the machine. For example, the activity LED only works with with the primary drive of the unit, whether IDE or SCSI for example. What I am going to do is have the main unit activity drive light for the boot device. Then have another LED that lights when say a SCSI device is active (probably yellow). And a 3rd LED for when the SCSI2CF unit is active (probably blue). A fourth LED that is a subdued white that will again be used internally if the case is open to let someone see inside easier if the unit is running for testing or whatever.

The internal LED (white) I use to draw power on the same connector as the fan, the others I draw the same way the original LED's are powered but depending on which device I want it to monitor of course.