Working safely with equipment powered from a 9v ac supply plug pack

[mkofler]

I have a DJ pre-amp mixer which that does not seem to power up. The mixer runs from a 9v ac plug pack.
I have checked the main power caps on the mixer power supply with an ESR meter and they are fine. The mixer power supply uses a 7815 a jrc and a 7915a jrc. I would like to test if the mixer power supply is ok.
I have removed the mixer power supply and disconnected the main board and I would like to know the safest way to test the mixer power supply. Is it safe to test the mixer power supply while running it from the 9 v ac 1 amp plug pack? If not, what is the best way to test whether the mixer power supply is working correctly?
Thanks in advance.
Mark

[EEVblog]

Is it safe to test the mixer power supply while running it from the 9 v ac 1 amp plug pack?

Yes, completely safe. The plugpack ensures electrical isolation from the mains. It's safe to probe around with your meter or scope.
Make sure the mixer is disconnected from all other equipment though.

[Anks]

You sure you have the right plug pack

[Macbeth]

7815 and 7915 would imply a split rail 30V (+15,0,-15) supply needed for op amps. Surely your PSU would supply at least 24VAC (0.707*24*2) for 34VDC?

[mkofler]

Thanks for the advice.
Yes it is the right plug pack.
9v ac is labelled on the unit.
I also found the same unit on eBay and the labeling is the same.
So if anybody is happy to explain why a 9 v ac plug pack seems odd that would be great.
Thanks in advance.
Mark

[Macbeth]

Thanks for the advice.
Yes it is the right plug pack.
9v ac is labelled on the unit.
I also found the same unit on eBay and the labeling is the same.
So if anybody is happy to explain why a 9 v ac plug pack seems odd that would be great.
Thanks in advance.
Mark

Because you state that 2 x 15v regulators (30v) which will require even more volts (1.4v for the bridge rectifier, as you state it uses an AC supply) + the high drop out these old 78xx/79xx uses would demand a minimum voltage much greater than 9VAC. Of course, being an unregulated supply and the pre-amp not needing much current, maybe a 12V wall-wart over a 9V job would do the job, just. Also, why are you scared of playing with low voltage isolated DC?

Perhaps seeing as you know labels, model, and part numbers you could post them instead of appearing to be an obtuse troll?