NI GPIB-USB-HS repair attempt

[matthuszagh]

This is a short post intended to document my so far unsuccessful attempt to repair a cheap Ebay NI GPIB-USB-HS adapter.

The first failure symptom was that it started to stall during an HP 3048A calibration attempt. Then, when I unplugged it and plugged it back in it would no longer show up as normal in the NI MAX application. The device manager and the NI MAX app both presented it as "usb\vid_3923&pid_709b".

The inside of the unit looks slightly different than some of the others I've seen posted online.



In particular, there is no part number on the IC that is normally labelled as an NI part. Additionally the pictures I've seen show a conductive shielding paint on the inside of the case. This unit doesn't have that.

A MAX604 chip regulates the 5V USB voltage to 3.3V for the USB controller (CY7C68013A), RAM (CY7C1399B), probably I2C EEPROM (24LC256) and possibly the NI IC as well, though I didn't check this. Probing the MAX604 showed 5V at the input and output. The next step was to determine if that failure caused any other devices to fail. So, I removed the MAX604, connected the USB cord (maybe some devices require the 5V) and powered the 3.3V rail from an external supply. No luck. The device now completely fails to enumerate. 3.3V current draw was about 40mA.

At this point I could continue to troubleshoot, but considering the fairly low cost of these knockoff clones, it might not be worth it. Also, I'm concerned that the 5V on the 3.3V rail could have taken out multiple devices.

I may just order another one of these, though I'd be interested to hear if anyone's had luck with other options (especially Ethernet-GPIB adapters). I'm not especially impressed with the durability of this unit considering the minimal use/wear it received. It also makes me nervous to connect it to more valued HP equipment.

[syau]

My unit failed in a similar matter and fixed by replacing the RAM CY7C1399B.

The failure mode  is a ! next to the usb device in window device manager.