Using YC USB jack for low power led lamp?

[obxa]

Anyone else do this?

 

When using the late great Kurzweil PC2,  I always plugged a single laptop type led lamp  into it's USB A when the Kurz was my bottom board.  Worked great for pit band and dark stages and never had a problem.

 

Wanted to do the same with the YC73's USB A port.  With the YC under my Nord,  tested perfect with simple LED gooseneck on low setting to illuminate the A/B section volume/filter knobs. Will help me avoid more cable clutter.

 

I know manufacturers warn about charging your phone and the like, but is there any real risk in leaving one of these plugged in for a couple hours on a gig?  Is it technically any worse than if you left a USB stick in ?    Hard to get exact specs; the lamp purchased on Amazon just says  it's "5 v"  which also seems to be what most Thumb drives are?  Reached out to Yamaha, for what the jack actually supports and continuous  risk factor,  but haven't heard back. 

 

Thanks in advance for any insight.

[Coker]

I’ve been doing that, but only for a couple months. All USB power is at 5V. What will matter is how many milliamps (mA) your device draws.  The manual warns not to use any device over 500mA or “the instrument” could be damaged. 

[obxa]

This is why I reach to those who know better than me.... and I'm way out my jurisdiction here.

 

More specs  found on the LED light:

SPECIFICATIONS
Power: 1W
Input: 5V / 0.5-2A
 

So how does one determine?  Used an online converter of watts to mA, simple enough: 1w=1000 mA.  (1000x1) Which would be way over.    Or is the stated lamp wattage in these kind of specs actually a milliwatt ( .001)?

 

Thanks!

[Coker]

 

 

It looks like your device exceeds the 500mA (0.5A) limit stated in the manual. I would not plug that light into the YC.  I double checked my light and found that its power requirements also exceed 0.5A, so I thank you for bringing this possibility to my attention.

 

I have added a “Y” to the power cord for the YC so there is a 110V outlet at the keyboard end.  I now plan to plug in a USB multiblock there so I can plug my light in. 

[CyberGene]

11 hours ago, obxa said:

So how does one determine

Electrical power = Voltage X Current

 

500mA = 0.5A

USB voltage is 5V

 

Hence, the most power the piano can safely provide is 0.5 X 5 = 2.5W. It should be more than enough to power that 1W LED lamp. 

 

More than 500mA can damage it (according to what’s posted by Cocker) but I guess there’s some protection inside the piano. Or, you can use a 10 Ohm resistor to make sure current is limited at 500mA. 

[Reezekeys]

Don't some of these little gooseneck LED lamps run on one or two AAA or AA batteries? I don't think those could provide "0.5 - 2A" for very long.

[Coker]

I think the issue may relate more to current drawn when charging the light's battery, not how much the led uses 

[obxa]

4 hours ago, Coker said:

I now plan to plug in a USB multiblock there so I can plug my light in. 

That's a good idea.  I currently have a multi on the floor going to two ipads,  plus a BT midi thru box which also needs usb power.  If brought up to keyboard level might cut down on the fugly factor. 

 

Thanks all.    Funny- Yamaha has "escalated" my inquiry to a senior tech. I'll keep ya posted if they go beyond the standard "don't charge your phone" response. 

[stoken6]

3 hours ago, Reezekeys said:

Don't some of these little gooseneck LED lamps run on one or two AAA or AA batteries? I don't think those could provide "0.5 - 2A" for very long.

Quite right. "0.5 - 2A" is I think a reference to the typical kinds of power output available on a USB A socket. (500mA comes out of a normal USB port on your computer, and 2A is I think the original iPad charger). LEDs are efficient, so I would be surprised if it's actually drawing more than 250mA out of that socket to fulfil its 1W power output, with a bit of overhead.

 

Cheers, Mike.

[obxa]

So Yamaha basically said, "just try it, worst case it won't work.."  I also reached out to the led vendor to see if they had any additional specs. 

 

As mentioned  did this forever on my Kurzweil with a 1st gen LED- never had a problem.  As Stoken mentioned, these new ones are much more efficient.  So much that even on lowest setting,  needed  a piece of painters tape covering the lens to knock it down a bit to not PO any LDs.  I'll have to ask for a scrap of old-school gel paper on the gig.