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Required Tools for Assembling a USB7

If your USB7 doesn't work perfectly, here are some troubleshooting tips:

Symptom Cause
Display doesn't power on, or USB over-current warnings, or diodes are very hot. Using your multimeter on 'continuity', check for a short circuit between the cathode of D2 (where it says D2) and ground. Also check for shorts between the bottom two pins of the USB connector. If your meter shows a short, find and solve it.

Make sure both diodes are installed in the correct orientation.

Check all solder joints.
USB device is not recognized but the display shows '000000' Check the 68Ω resistors and make sure the D+ and D- pins of the USB connector are correctly soldered.
USB device is not recognized and the display shows gibberish. Make sure the Atmega168 is securely seated in its socket and all the pins are well soldered. Check the resonator, check the electrolytic capacitor.
A single segment on a single digit does not illuminate. Check the soldering on that digit's pins.
The same segment on every digit does not illuminate. Check the soldering of the 82Ω resistors. Make sure the Atmega168 is securely seated in its socket and all the pins are well soldered.
A single digit does not illuminate. Check the soldering of the 1KΩ resistors, and the transistors. Make sure the Atmega168 is securely seated in its socket and all the pins are well soldered.
If you use the same character more than twice in a row, it doesn't always appear. This is a weirdo HyperTerminal error. Follow these steps to resolve: From the 'Call' menu choose 'Disconnect'. From the 'File' menu choose 'Properties'. Click 'Configure'. Click 'OK', then 'OK' again. From the 'Call' menu choose 'Call'.