#A500 PS Problems?
4 messages in this thread
Hi all,
I have a small problem — I was getting lots of snow on my screen today (am
using an Amiga A500 with no peripherals connected, 1MB of RAM). I
disconnected the power supply (after turning everything off, of course),
and then plugged it into the wall and tested the output from the other end.
It read +6 volts for the +5 volt output, +13.5 volts for the +12, and -11
for the -12. I opened the little monster up and adjusted the -11 up to -12
(no load). Should this help the snow at all? The snow shows up whenever the
floppy is accessing, or in particular when the mouse use is heavy, and at
those points the power supply puts out a kind of high-pitched wheedling
sound (steady, quiet "wheeeeeee" tone). Could the snow be due to brownout
conditions (lots of air conditioners on in the building today). Should I
replace the brick with a third-party equivalent? Are the +6 and +13.5
voltages due to absence of load from the computer's circuits? Any help on
all this (fast!) would be muchly appreciated — thanks!
–steve w.
Steve,
Yes, the higher than normal voltages are due to testing under no
load conditions. Power supply output is rated under loaded conditions.
The sound you hear is probably the power supply being overloaded.
This could easily occur on the A500's power supply if you're running close
to it's rated limit and then have a brownout. As the voltage lowers during
a brownout…the power supply must work harder to keep up.
Yes..I'd strongly suggest you get one of hte higher powered
supplies that are available.
Don
Don,
Thanks! I'm always willing to live with the current situation as long as no
hardware damage is occurring — hmm, but maybe I'll order a third-party
"brick" just in case (my summer power supply?). 🙂
— steve
Steve,
I didn't say you couldn't do any damage.
Power supplies can blow one of two ways. They can die and stop
putting out power OR the regulators can short and put out too much
voltage. The first won't usually cause you any harm, the 2nd method can
also blow the computer.
Again…I strongly suggest a higher powered supply.
Don