I am hoping you kind people on this forum can help me figure out what i need to repair a very expensive and out of warranty piece of equipment. It is an EEG amplifier which connects to the computer via a USB cable. When plugged in, it is not being recognized by the computer. Ive narrowed it down to a fault in the USB data circuit (see troubleshooting1.jpg and a blown up version in troubleshooting4.png). This is my first time opening this up, but it seems at some point someone really did a number on the trace (D- or D+) exiting the USB terminal.

I wanted to bypass this broken circuit with a jumper cable attached to the other side of the board. I dont trust my ability to fix the broken trace. I want to know what the black component is on the bottom half of troubleshooting4. A naive search led me to "transient voltage suppression diode", but i have no idea what kind. Seems important.

In case it is relevant, after the data lines pass through this component, they go to the D-/D+ terminals of this chip CY7C68013A-100AXC | USB 2.0 Peripheral controller with 16K RAM, 40 GPIOs, serial debug, 100-pin TQFP for non-battery powered applications - Infineon Technologies

I really appreciate any help you can give!
-Andrew

 

Welcome to AAC!

Unsolder that black component so that you can clearly see how the PCB tracks are routed.
For now, just jumper across the gaps with fine wire-wrap wire.

Show us a photo of the first IC connected to the two tracks.

 

side shows windings so it is some sort of inductive device, most likely common mode choke.
for example:
https://www.digikey.ca/en/products/...VskT_AR3HRhHFEAQYBCABEgICcPD_BwE&gclsrc=aw.ds

 

Welcome to AAC!

Unsolder that black component so that you can clearly see how the PCB tracks are routed.
For now, just jumper across the gaps with fine wire-wrap wire.

Show us a photo of the first IC connected to the two tracks.

Hopefully this is what youre looking for? My potential solution was to jumper 4 (good - has multimeter continuity from the USB connector pin) to 4 (bad - does not have multimeter continuity from the USB connector pin)

 

Well i removed the component and immediately lost it after my tweezers flung it across the room. The component was bridging the disconnect in the two parallel lines. I connected those traces with two wires, confirmed that they were connected and not bridging one another. It has not resolved my issue though. I still dont get the amplifier showing up as a USB device when plugged into the computer. I have another amplifier that works, and confirmed it is not a cable or computer port issue.

Ive attached images of my wiring attempt (you see why i was hesitant to do this), and more images of the component on the working amplifier. The notches on the ruler in the last picture are 0.5mm

 

side shows windings so it is some sort of inductive device, most likely common mode choke.

Perhaps maybe this? Looks to be the right shape and size. No idea which variant
1206 USB 2.0 Common Mode Choke

 

Even if choke is defective, i would not bother with it until confirming that IC is ok. So for the time being, i would simply bypass it if needed.

 

It seems I am way out of my comfort zone then. I'm not sure how to check if the IC is ok. There is no heating or discoloration. All the contacts appear good. I am able to confirm the chip is getting 3.3V of power. I also checked the crystal oscillator is producing a 24MHz sine. Id appreciate any advice for what to check on the CY768013A chip.