Amiga 600 Power Supply

[SteveSJB]

Hey all,

Last night, just as I was about to have a night of passion with my 600, she decided I just wasn't right for her and left me.

After 2 hours of having her in bits, multiple visits to websites and trying all the tricks I know - eg. reseating rom, cables, cleaning - She still decides not to come back.

I will never throw her away - i'll keep her as spares and just buy another 600 off ebay.

However, before I do that, there is one thing I have not tested, the power supply.  When it comes to testing electrical components with a multi-meter - I am an absolute novice.  As such I have a couple of questions about it - please be aware though since I am such a beginner with testing, I need things explained simply and in detail. (I don't really want to blow myself up :-) )

After looking at websites, I understand that there are 5 pins - 1=  +5v 2=  Shield Ground 3= +12v 4= Signal Ground 5= -12v

1. I take it the power supply needs to be plugged in and switched on?
2. Do I start with the NEG meter terminal on pin Ground and POS on pin +5v and see if it reads around 5v
3. Same, but with the POS on +12v and make sure it reads around 12v

Anything else you can add would be very appreciated.

Many thanks in advance.

-Steve

[amiman99]

Hold the Negative lead against the Shield GND and use the Positive lead to do the measurements.
I get 11.7V, -11.58, and 5.05V on mine.

Good luck.

[SteveSJB]

Many thanks for a response, I will try what you suggest and will probably print the results here to see if they are ok.

thanks again

[SteveSJB]

Ok the results I get are:-

 14.28V
-14.39V
  5.14V

Are these results ok?

Many thanks

[amiman99]

Looks like +/-12V is a little too high. According to this site http://www.ianstedman.co.uk/Amiga/amiga_hacks/Amiga_Power_supplies/body_amiga_power_supplies.html max 12V line s/b 12.6V not 14.3V like you have.
Verify it again to be sure, maybe from the 0V pin not the shield. I have one A500 PS that does not measure anything if I use the shield as 0V GND.
Do you have another PS to cross reference your results?

[SteveSJB]

Yeah I forgot to say I had no luck when using the Shield GND, had to put the NEG probe on 0V GND instead.

Retested and got the following results:-

13.80v
-14.25v
5.29v

Unfortunately, I don't have a spare PS to check

[nscaleworld]

Yeah I forgot to say I had no luck when using the Shield GND, had to put the NEG probe on 0V GND instead.
 
Retested and got the following results:-
 
13.80v
-14.25v
5.29v
 
Unfortunately, I don't have a spare PS to check

The 5 volts is fine.  The 12 volt lines are too high, especially the -12 line.  I have an Amiga 600 power supply that I could send to you.  An Amiga 500 psu would be better, because they are higher quality and put out more wattage.

[SteveSJB]

Hi, ty for a response.

I take it then that trying to repair a power supply is too advanced?

Thank you for the offer of another 600 PS, how much would you want for it?

Many thanks.

[duga]

An Amiga 500 psu would be better, because they are higher quality and put out more wattage.

Please, don't spread that myth.

Old, heavy A500 PSU: 2.5A@5V - avoid if possible
Newer, light weight A500 PSU: 4.5A@5V
Light weight A500/A600 PSU: 3.0A@5V (the same as the A600/A1200 PSU)

[duga]

Yeah I forgot to say I had no luck when using the Shield GND, had to put the NEG probe on 0V GND instead.

Retested and got the following results:-

13.80v
-14.25v
5.29v

Unfortunately, I don't have a spare PS to check

It should read +/- 5%. That is:

11,4 - 12,6 volt
-11,4 - -12,6 volt
4,75 - 5,25 volt

Get another A500/A600/A1200 PSU.

[nscaleworld]

Please, don't spread that myth.
 
Old, heavy A500 PSU: 2.5A@5V - avoid if possible
Newer, light weight A500 PSU: 4.5A@5V
Light weight A500/A600 PSU: 3.0A@5V (the same as the A600/A1200 PSU)

Not a myth.  Why do you think Amiga 1200 owners buy Amiga 500 power supplies?

[duga]

Not a myth.  Why do you think Amiga 1200 owners buy Amiga 500 power supplies?

You wrote: "An Amiga 500 psu would be better, because they are higher quality and put out more wattage."

Not all, but _some_ A500 psu:s put out more wattage on the 5 volt line. You have to make sure you get the right model, that's my point.

2.5A x 5V = 12.5 W
3.0A x 5V = 15 W
4.5A x 5V = 22.5 W

[SteveSJB]

Just to give you all a quick update, I received a new (2nd hand) Amiga 600 today in the post.

New Amiga + New Power Supply = Working
New Amiga + Old Power Supply = WORKING!
Old Amiga + New Power Supply = FAULTY!

Very strange, that means that there was a problem with the Amiga all along and the power supply was fine!

Many thanks

[nscaleworld]

Now you see why I hate the "surface mount" Amiga models.  Nothing but problems with the pieces of crap.  This includes the Amiga 1200 and 4000 models.

[Tenacious]

Yeah I forgot to say I had no luck when using the Shield GND, had to put the NEG probe on 0V GND instead.

Retested and got the following results:-

13.80v
-14.25v
5.29v

Unfortunately, I don't have a spare PS to check

Its too late now, but, switching power supplies should always be measured while LOADED.  That is, connected to, and powering the computer they are designed to run.  You may have to read the rails (+5V, +12V, -12V, etc) inside the Amiga, since the connector will be plugged in.  The rails should be within say, 5%, and most importantly, not drift very much.