x68000 xvi power supply repair

[pstriolo]

Hi all,

I just received a x68000 XVI from japan with what i supposed to be a faulty power supply. The unit doesn't fire up (only the 16 Mhz led turning to green and nothing more). I just test the power supply inside and found only 2V on a 5V line going to the motherboard, and -10V instead of -12V. I think that some components are dead inside the power supply.

I would like to repair the power supply by changing to an external ATX power supply.

I found on lawrence's page on the web, a schematic using a 74Ls04 circuit. The question is : is it obliged to use such trick or connecting directly the 5V from the ATX power supply is sufficient ?

Thanks for your help.

Philippe

[NFG]

1. Getting low voltages on a live system is normal, that doesn't really mean anything.

2. A dead PSU will generally not work AT ALL, no lights no nothing.

3. an XVI with a more serious fault will do what you describe.  I've seen that happen several times.

4. The 7404 chip is required, do you think it's there to make the system look better?  

[pstriolo]

Hello,

I just finished to make a new power supply with an ATX power supply and the 74ls04 chip with the help of the web page from lawrence.

It just work now fine and i'm terribly happy. My xvi HD is returned to life. :lol:

I will now try to take some times to find what was wrong inside the original power supply. One thing that was pretty curious is that the power supply started when i just turn the on/off switch on it and without the power switch from the x68000. It normally don't start this way and only the red led should appear. But in my cas it started. :blink:

Thanks a lot lawrence for your help.

Philippe