Ooops!, Has that blown it?

[Tim]

Last night, being tired, I plugged a 13.5v DC cable from my power supply into the supply socket for my USB hub, which normally takes a 5v 100ma DC adapter.

After this, the Shoestring Astronomy GPUSB adapter and also the reciever for my wireless gamepad no longer work. The USB hub itself is fine.

Are they fried? I'm not so concerned about the gamepad, but the gpusb cost me a nights imaging last night, as I couldnt get the guidehead I have to focus through my off axis guider, not to mention I was trying to learn to use Maxim on the fly, which didnt go well....

The electronics in the GPUSB seem pretty simple, what would be most likely to have gone, a little cheap resistor perchance?

A new GPUSB is 75 quid, and it seems such a shame if there isn't too much wrong with the old one, that a soldering iron cant fix....

Anybody got any ideas?

Thanks in advance

TJ

[arad85]

Are they fried?

If you can trace the fault to when you plugged in 12+V, then in all likelihood - yes. It's like asking your 230V hair-dryer to accept 600V and still work....

The reason for that is the hub is likely to filter the voltage for itself, but pass the voltage to the USB ports directly.

[Mikea]

I think if you are hoping a cheap resistor is the only problem, you are asking a lot! I have no idea what's inside one of these things. Do you have a photo of its insides?

[barkis]

That is bad luck mate. Easy done when the old Sandman is rubbing your eyes. I would change the plug sizes to prevent a recurrence.

Ron.

[barkis]

Possibly blown a track on the pcb. Living in hopes mind you, but worth a look. If you find a break, bridge it by soldering a link to the first soldered connection either side of the break.

It's a wing and a prayer job though.

Ron.

[jgs001]

It's a tough one TJ. I hope you're able to fix it.

[Beyond_Vision]

It will most likely have knackerd any IC's within the GPUSB as they would run directly off of the 5v supply. It is unlikely that there is any sort of regulation in the device which would offer any protection.

Regards

Kevin

[blinky]

Yep I agree with Kev - pretty sure an IC will have blown. I would check the part numbers of them all (IC's that is) and replace them.

[steve51450]

tj

if you can pop over to mine the weekend you can lend my gpusb for the weekend so you can guide and check the wiring against yours. I am pulse guiding at the moment so its just a backup.

I can give you some maxim tips as well if that helps

[Tim]

Cheers Steve, I might just do that, i'll give you a call if so.

Here's a pic of the PCB, it's pretty simple. A few small resistors, couple of round things, and a couple of what I only know as "microchips".

What is most likely to be damaged? I have a multimeter I can test with if needs be.

Thanks for the help, much appreciated.

Tim

[Psychobilly]

If the Pics dead .... and I reckon its a fair bet that it is... Well your ...in a bit of a fix... as its a progammable micro controller... Shoestring would be your only hope of a spare... you can buy a replacement pic ... but it useless untill its been programmed with the "GPUSB" code...

Peter...

[Tim]

oh, so its not a simple as whacking a new bit in then. Darn.

I'll contact shoestring and see what they say.

[Psychobilly]

The pic on it's own is cheap... Sorry Tim

Peter...

[Tim]

Just had a thought.

I use EQMOD via EQDIR. This controls the mount, so would it also control it for autoguiding? I guess it would be selected as ASCOM in the PHD mount selection?

Cheers

[SteveL]

yes, and select EQMOD in the ASCOM chooser. EQMOD allows multiple applications to connect to it at the same time.

[MikeP]

You'll also need to enable pulse guiding in EQMOD.

Mike

[Mikea]

I concur with peter: I checked the Microchip PIC16C745 datasheet (clever little beast has 165 pages of data!). Absolute max VDD is 7.5V, so 13.5V would almost certainly have toasted it. The white object, top left on pcb, is an optocoupler and would probably have blown its little socks off too. Sorry TJ.