Is my PSU working correctly?

[richard]

I think my PSU isnt working too well.

When I check the pinout the 12v and -12v seem a bit low. They both read about 11.73v.

Will this cause problems or doesnt it matter.


I have a A500+ with a GVP HD8+

Thanks

[Druideck]

doesn't matter, unless it don't work at all.  :-D

[Doobrey]

I wouldn`t be worried about seeing 11.73v instead of 12v.
 How accurate is the meter you measured it at?

[odin]

@druideck:

Actually a half working psu can be quite annoying. My peecee PSU quit working at irregular intervals :-D.

[unclewilli-amigalover]

is your 500 doing anything strange / weird reboots, light getting real dim smell something burning? can't hardly trust some meters.

[that_punk_guy]

11.73 volts is absolutely fine. The components in your computer will tolerate slight variations in voltage (if you can get hold of any data sheets they probably have the figures on there).

[KapitanKlystron]

Yes thats less than 2.5 % variation. Even ####uming that your meter is that accurate. Besides, depending on the number of ohms per volt of your meter it couldbe loading down your supply.

[Floid]

that_punk_guy wrote:
11.73 volts is absolutely fine. The components in your computer will tolerate slight variations in voltage (if you can get hold of any data sheets they probably have the figures on there).

To elaborate, most 'modern' electronics (where 'modern' is somewhere between 1975 and 1990) have voltage regulators onboard.  These are little semiconductor devices that help clean up the power on the way to points important, though my knowledge of the physics is rusty, so I won't pretend to know how they work.  It's only when you exceed the tolerances for these and related components that bad voltage becomes an issue.

Other fun things to try:

-Compare 'opposite' voltages and see if the skews even out.  (Okay, you did, nevermind.)

-Compare data ground to chassis/electrical ground.

What you really want to watch out for are things like fluctuation or waver; those can indicate an underpowered or failing supply.

[richard]

Thanks for all the help.

The only thing strange that my computer does, is that the serial port stopped working.

[JimS]

The Serial data goes thru the Paula chip, and the contol lines come from one of the 8520s. If you've got a spare Paula, swap it out & see what happens.. You can swap the 8520's since there are 2 in the machine.  However, the serial port is buffered through a set of driver/reciever chips which are soldered in.   Incidentally, this is one place where the 12v is used.
There ought to be a way to do a "loopback" test by jumpering transmit data (pin2) to recieve data (pin 3) and using a terminal program in half duplex... Off hand, I don't remember if any of the other pins need to be connected for this..