Sharing a 5V power supply between 2 devices

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omnigate

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I'm new to the forum and hope this is the correct place and format for this question. One of my businesses is vending. I starting using Air-Vend devices that allows the user to swipe their CC for purchase and also to transmit inventory info. Recently, AV has been having issues with their devices crashing and not booting. I decided to open one of them up just because I was curious what components were inside.

The main board inside the device receives power from the vending machine and has an output connector that is labelled 5V. This cable attached to this connector then splits between a small tablet (people can get nutrition info) and a USB Hub. The power connector on the tablet reads 5V. I couldn't find anything on the USB hub but looked at my Belkin and it's rated at 5V too.

So my question is this - Should 2 devices rated at 5V be sharing a 5V connector? Or should there be two 5V connectors on the board - one for each 5V device?

Here are some pics I took - http://www.ond360.com/air-vend.php
 
I will allow this even tho the op is not in the trade as he is only asking a question

IMO, it has more to do with the device that gives the 5V and what it is rated. In theory you can have many devices run on 120V but the wattage adds up and if the device supplying the power is not rated for it then there will be an issue.

I have no idea why it is crashing but I don't the 2 connections are the issue
 
Do you know which USB power standard is being used? USB power or charging comes in two basic sizes of 500 ma max, and 2-amps. The current limit of the supply and the amount of current required by each device is going to dictate what can or cannot be done.
 
One of the problems with powered USB hubs is that the USB standard AFAIK does not say anything about the input power needed by a powered hub. But the hub should not require much more at the input than it is being required to supply at its output.
Unpowered USB hubs are usually not able to supply full USB power to all of their outputs from what is available at the computer port.

Sent from my XT1080 using Tapatalk
 
There's many uses for USB's, and styles and there's many applications.

If you click on one diagram they usually have several more behind them.

Diagram USB

I didn't drop anything in here because everything seems copyrighted! There are some
like diagrams that you question about after the first third of the page

If a board fails it's just that.

Hope this helps...
 
omnigate said:
Thanks very much for the replies, I will check into the rating for both Amperes and Wattage!
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The manual may contain the information on/in the specifications, if provided. In many cases, one way to determine the power required at DC power inputs is to glean it from "wall wart" power supplies that come with or sold as an accessory specifically for the equipment being researched. Short of that, you will have to consult manufacturer technical support... and I wish you good luck with that :p
 
omnigate said:
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So my question is this - Should 2 devices rated at 5V be sharing a 5V connector? Or should there be two 5V connectors on the board - one for each 5V device?

...
Click to expand...

One connector is fine. The power supply must be sized to accomodate the two loads plus there's likely other 5VDC circuits on that board. I'm sure whoever designed that circuit did the "load calculations" as they would call it on this forum. What happened though is load was added to the vending machine, but let's leave that off the table.


If you have an issue of crash and no reboot, that's a software issue. That device may receive software updates via the usb wireless adapter. If that's the case, I suggest you call them and ask them to roll back the software to that which previously worked.


Is that USB a wireless device dependant upon a local router, or is it a cell phone adapter?
 
Smart $ said:
It's a cell adapter (Verizon Pantech 4G LTE USB Modem).
Click to expand...

Your power question has been asked and answered. To diagnose this via a message board might take longer than you want but let's take a stab at it.

Please describe symptoms. I'm guessing you get a call where someone tells you your vending machine is not working? Is this occurring in areas where you know there's plenty of cell signal available? Have you ever seen it fail?

Most importantly have you called the company that makes it? Have you called whoever sold it to you? I would think both of them have an interest in it being a success for you. They should be able to call it- it uses a 10 digit phone number just like any other cell phone; I have several but not for vending machines.

Do you have this problem with just a single one of these? (how many do you own?) Or is it a problem with all of them? How long has this product been on the market?

Update: I just looked up Air-Vend. That's a band new company and this is brand new technology. They need to fix it! And I would think they would WANT to fix it. They don't want people running around on message boards saying their stuff doesn't work, and they want you to be happy with it and use it more, so get ahold of them. If they won't fix it, maybe that will tell you whether you should use their stuff.
 
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i can read the numbers on the ptc fuse just above the 5 volt jack on the board but i noticed there is a mini a usb port nearby. that means that the usb host controller and that dc bus may be on the same fuse that is a 1.1 amp fuse if there are two that i can see on that board in the psu input stage both are 1.1 amp hold 2.5 amp trip self resetting fuses. i use them in the pem sections of the servers when i build them.
the 7 pin package just to the right of fs1 is the dc/dc regulator that powers the entire airvend sbc board. this device when it gets to hot will shut down in overtemp mode and cause the board to crash, if you could post a clear photo of the entire board i can most likly solve the issue with the lockups. a temporary fix would be to obtain an externally powered usb hub and plug the tablet and rfid into that and just use the air-vend sbc to run the usb port the hub plugs into
 
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