Regulated vs. Non-regulated Power

[Cloudschatze]

Here is a random sampling of the DC output from a few Roland, 9-volt power-supplies:

12.47V
12.39V
14.54V

I realize that variance is to be expected, but a 5.5V deviation seems a bit high. At what point should the purchase of a regulated adapter be considered, in lieu of possibly needing to replace a voltage-regulator later on?

[Alistair]

Here is a random sampling of the DC output from a few Roland, 9-volt power-supplies:

12.47V
12.39V
14.54V

I realize that variance is to be expected, but a 5.5V deviation seems a bit high. At what point should the purchase of a regulated adapter be considered, in lieu of possibly needing to replace a voltage-regulator later on?

Eric,

Is it possible that such variances would lead to electrical interference or damage to equipment?

I'm worried about my adaptors now. how'd you sample it exactly?

- Alistair

[mace]

Actually, I suspect you have tested them without load. Is this correct?

Older power adapters, the ones using plain transformer technology, have a higher voltage output when not under load.
I suggest you put a heavy duty wirewound resistor between the poles and then test again, you will find the voltage will drop.

Newer switching type voltage supplies do not have this fluke (I won't say problem because it isn't)
They simply give off the correct voltage and if they are left without load, they tend to oscillate and then the voltage drops.

Neither is problematic, the only problems arise when the voltage isn't within spec when the supply is under load (i.e. normal use)

[Laust]

The standard 78xx voltage regulator can handle input voltages beyond 30V, so I don't see why it should break if the input voltage is slightly over what Roland recommends. And as mace points out, measurements from an unloaded non-switching power supply really don't mean anything.

[Cloudschatze]

I appreciate the explanation, and yes, these were no-load measurements (taken with a basic multimeter).

I found this article too, which describes the goings-on fairly well.

[Patrick Chang]

Here is a random sampling of the DC output from a few Roland, 9-volt power-supplies:

12.47V
12.39V
14.54V

I realize that variance is to be expected, but a 5.5V deviation seems a bit high. At what point should the purchase of a regulated adapter be considered, in lieu of possibly needing to replace a voltage-regulator later on?

Well Cloud, I don't know if the following link would answer your question. It's a list of Roland & Boss Power Supply Compatibility Guide. Please select "Adapter Guide" on the bookmarks to find out recommended Power Supply for ya Roland musical equipment.

http://media.musicalplanet.com/pdf/ROL147.PDF

I am quite surprised to find out my CM-500's original power supply isn't on the roland's compatibility list.   

PC.

[Cloudschatze]

Hi Patrick,

Thank-you. Mace and Laust had pretty-much answered the question, but I appreciate the link you provided, and it should be helpful to others.