Dead V2 on USB only

[DURAtotheMAX]

Plugged my V2 in today to USB, and one of the lights came on, but the screen did not come on...windows said "unrecognized device, or there is a problem with the device".

Worked fine yesterday.

If you plug it into an OBD port, it powers up fine, but still wont communicate with a PC in pass-thru mode...so there is something wrong with the USB section.

I opened up the V2 and did some probing around, looks like the ground pin on the USB connector doesnt have a very good ground connection with the ground plane on the V2's circuit board. The ground pins on the RJ45 connector for the OBD port have 0 ohms to the ground plane on the PCB, so thats fine, but the USB connector shows about ~40 ohms pin to ground plane. I tested all of the pins/connections on the "data line protection" chip, the ST USB61, since it was the first thing that goes to the USB connector. I looked up the datasheet for the USB61 and figured out what readings should be...and it looks like something is wrong with the trace between the USB connector and the GND pin on the USB61.

Also, I was only reading about 3.9-4.0v on the V2 (probing the Vcc pins of various chips on the board) when powered up via USB. I assume the thing works on 5v and not 3.3v.

I wasnt sure if there was supposed to be any resistance, if there was some capacitor or something in the USB ground to V2 ground plane...but since the RJ45 ground from the OBD port is tied right to the internal ground plane of the V2, I figured there was a problem with the USB connector.

So I figured I had nothing to lose (my V2 is probably 8+ years out of warranty) so I shorted the USB ground pin directly to the V2's ground plane, plugged it in, and now it works perfectly!!

So my next step is to desolder that USB61 chip and see if theres some bad connections, or a bad trace where it passes underneath the USB61.

Ill report back my findings, but I figured I would post up my temporary "fix" if someone else is having a similar problem. Obviously do this at your own risk, and dont do it if you dont have soldering experience and electronic circuit design knowledge... I just needed my V2 today for important work and dont have time to send it off to be fixed.

Ben

[joecar]

The USB socket's ground pin solder has probably cracked from many insert/remove cycles.

[DURAtotheMAX]

The USB socket's ground pin solder has probably cracked from many insert/remove cycles.

Nope. Tried reflowing it, no dice.

There is zero ohms between the pin on the USB port and the pad on that little "USB62" SOIC-8 chip, so there is nothing wrong with the USB port itself.

I used my hot air rework station to lift that little USB6B1 chip off of the board and see if anything was wrong underneath it.

I think the USB6B1 chip is fried. I looked up the datasheet and basically its just a bunch of fast-acting diodes setup in a bridge across the data lines, Vcc and Gnd to protect against spikes and transients.

Theres 0 ohms across Vcc (+5v), Data line 1, Data line 2, but Gnd in to Gnd out has ~40ohms resistance. From looking at the datasheet, it should be a straight passthrough, so something is wrong there.

Ill order another USB6B1, solder it in, and see what happens.

Ben

[DURAtotheMAX]

I absolutely NEED my V2 tonight to tune a customers truck, so I made a temporary fix that was a little less precarious than my original wire jumper.

Found a via on the board that tied to the ground plane and was close to the USB port Gnd pin, and soldered a little jumper from the USB port pin to that ground via.

Works fine. But obviously Ill be replacing it with a proper USB6B1 chip when I get the chip in.

I stupidly lost that little capacitor that goes from the "I/O 2" pin to ground...but it looks like that was an afterthought anyways (soldered onto the pins, so it obviously wasnt incorporated into the original V2 PCB layout/design), so hopefully it will work ok for the time being without that capacitor in there.

I know its a long shot, but would anyone happen to know the value of that little 0603 SMD capacitor?

Thanks
Ben

[joecar]

Google should locate a spec sheet for that cap.

[DURAtotheMAX]

Google should locate a spec sheet for that cap.

There are thousands of different capacitor values...unless someone on the internet posted the V2 PCB schematic, I doubt Im going to find it.

[DURAtotheMAX]

There was some "crap" under/around the pins of that USB6B1 chip...as shown in the picture, when I removed it from the PCB.

Ive never gotten my V2 wet, but Im guessing after leaving the V2 in the truck, exposing it to temperature swings, etc...over the years, condensation must have gotten to it.

Do the newer V2's have the PCB's coated/encapsulated? Mine is old old, I got it when the V2's first came out.

Ben

[joecar]

Leaving anything in vehicle cab overnight will allow it to see condensation (on the inside of the cab).