z63a USB ports not isolated?

Hi all. I've noticed something strange and I'd like your thoughts. This is especially of interest to me as I'm hoping to grab one of the last v6va IPSs... but I've got to know this problem is not a design flaw of the Asus', but rather something wrong with my specific unit.

When plugging in any USB device, the device powers up and runs just fine... for a while. Every so often, the device will disconnect and reconnect itself.

The second symptom is what really concerns me: if I have 2 devices powered from the same source (say the wall) and plug them both into any of the three USB ports, an over power situation seems to occur; the devices act at though they have too much power running thru them (I can explain this further if needed, but maybe its enough to trust I've had this verified by an electrical engineer). Unplug one of the two, and the problem goes away.

This makes me think there is no isolation between the USB ports. This is a bad thing for me as I connect to very delicate electrical devices all the time via USB.

I've never had this problem with any other laptop I've had. Is this a problem with my z63a? Is this a known issue with Asus? Can I expect the v6va to share the same issue?

Thanks in advance.

 

I've never heard or seen this before...... I'd see what's up with your unit first - maybe looking into running you computer stuff through a clean power surge protector from Monster or something as well.... something isn't right - but I can't say it's just on the computer side.

 

Thanks Justin. I'll do a bit more investigating. I almost found this out the really hard way; nearly popped a VERY expensive piece of equipment because of it. Can't let it happen again.


PS: I've held off on the BT install because of this. I don't want to send back a unit for repair after having cracked the case only to have them say "out of warranty".

 

USB spec is for a +5V VCD, Data +, Data -, and a Ground pin. The +5V line is good to 500mA for each plug. Devices requiring more then that need to use wall power.

I don't see how what you are describing could occur unless you have either a defective device or a defective laptop. Plugging in multiple devices shouldn't affect each other. The wall portion of the circuit for each device shouldn't be directly connected to the USB portion of the device. Since each plug is required by the specification to deliver 500mA on the +5V line, those would have to be seperately regulated.

I'd plug your devices into a good power conditioner - maybe go further then a simple surge protector and get a UPS with voltage conditioning, etc.

Is everything plugged into properly grounded outlets? Is the utility line grounded properly to begin with?

Can you explain the device behavior in more detail?

 

Yes. This is the first thing you need to check. Improper ground can cause all kinds of nasty things. Surge protectors will not work and will actually leak 120V AC at very low current into all ground cables witch are then connected to various parts of your computer. maybe even the USB connector.

 

Thanks for the responses fellas. Let me try and explain, as best a I can (cut me some slack here, I'm a software guy, not a hardware guy

1) I've got device A plugged into a 3 pronged outlet, in my office.

2) Device A has 2 DB9 ports: (1) for connecting a programming cable to a PC via USB (DB9 on the device end, USB on the PC end). (2) is for plugging in devices that support RS232, RS422, RS485, USS protocol ect... basically its a completely open port for any protocol I choose to use or write. (2) also has the handy advantage of providing 24v DC to power anything plugged into it if needed.

3) Device B is an interface (HMI) for device A. It also has two ports. #1 is a DB9 for programming via a USB cable, and #2 connects to A's #2 port (these communicate via a PPI protocol over 485). B does draw its power thru A's #2 port.

4) Take the z63a out of the picture for a moment... we've got 110v coming into A, A then provides 24v to B, via port #2. This works wonderfully, has been working for years and we've never had any issues.

5) Put the z63a in the picture... 110v into A, 24v from A into B via port #2, and now plug in the Asus via USB to port #1 on device A. Still no problem at all. Similarly, connect the z63a to B via port #1 and no issues.

6) The problem is when A is connected to B (via ports 2), the z63a is connected via USB to A, #1 AND B, #1. When this happens, B seems to overamp (we see this via the HMI backlight... looks way to bright like its going to burn out). Also, A just acts weird (hard to explain). Lastly, comm between A and B via #2 is intermittent.

Whew! Confused? I should also note it doesn't matter if the z63a is on battery power or wall power.

Any thoughts?

 

Sounds like a computer problem to me, not a power problem.

It does this while it's plugged in and on battery power?

If so then it's a computer problem.

Talk to your reseller.

Cheers,
Mike

 

Okay, now it makes a lot more sense that something weird might be going on.

When you say everything has worked beautifully for years, I assume you mean with the two USB connections plugged into another computer...

In which case, you have a computer problem, contact your reseller.

 

Shampoo: Yes, this problem presents itself on battery power or wall power.

Jumper: Yes. This setup works fine for any laptop I've plugged in, except the z63a. The same setup I have the problem with when the z63a is in, just yesterday was plugged into a Dell instead and it had zero issues.

I'm convinced this is a computer problem. But, my question is... is this just something that has gone wrong on my specific z63a or rather is this a design flaw in some way?

Also, I'll try talking to my reseller... but what am I going to say? My guess is they'll say there is nothing they can do since technically, everything seems to be working just fine.

 

The 110V is AC; the 24V provided from board 1 to board 2 is DC, correct?

It sounds like you've run into an unforseen design issue; I don't think they expected to have to deal with two separate USB devices that also have a common power supply, and now you're getting a current loop running through the laptop. You should get a multimeter and check the current passing through if you can... As jumper said, the boards should have been designed with a USB interface that was independent from the wall power circuit since USB power isn't likely being used anyways, but it seems they did not. It may very well be that the laptop's USB ports aren't isolated or filtered properly as you mentioned you've used all three USB ports, even on opposite sides...

One thing you could try is to get another independent 24V DC supply for your HMI board.

Edit: Obviously misread the stuff about the USB ports being used...

 

Although I didn't state so, I have tried all three in varying combos Mystic; all had the same result. And yes, the 24v is DC.

The independent 24v supply is a good idea, but unfortunately impractical. We'll be in the field all the time with this notebook, and the location (clean room) and constraints of the machine itself prevent any external supply usage. Still, it might be a good thing to try on a test bench... just to find out.

So lets say it is a design flaw. Is there any way to know if this is common to Asus boards? In other words, can I be reasonably confident I'll have a similar issue with a v6va?

 

I still don't see how this could happen if both devices and the laptop adhere to the USB specification. It just boggles my mind.

 

ok now I'm VERY curious about this thread, I was planning on replacing my dell 8600 with a z63a but I really don't want to toast a $5k router when going to program it. I will be using a few similar adapters but not the same power that you do.

 

There is the possibility that my devices don't comply, and that every laptop I've plugged in for the past few years (20+ laptops in 5 years?) has handled whatever issue the devices presented... I doubt it as again these are highly sensitive and widely adopted devices. I would think this would have shown itself way before I came on the scene with my Asus.

On the other hand, IMHO I find it far more likely the Asus either (1) has a failure of some kind that allows the devices to work normally, until two or more are plugged in, or (2) there is a design flaw on the z63a. If 2, it wouldn't surprise me to find this is a common issue to Asus boards.

 

I'm curious to know whether it is coming through the USB power lines or whether it's because there's a DC offset coming off of the data lines, actually... maybe you could d/c the 5V USB power line and see if something works. It's too bad... I'm not familiar enough with the USB standard to know exactly how things are supposed to go, though, so it's a pure guess.

Is the backlight purely power-on/off only or is there an additional controller that can adjust its brightness? Can you check the voltages entering the backlight?