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Improving front USB reliability

My PC's front USB assembly is very unreliable. It looks like this:

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Basically it's just a straight connection. USB devices attached to it tend to disappear and reappear at random. I had a look at an Asus backplate USB assembly that works much better and tried to draw a schematic out of it:
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Though I'm unsure about some of the values. L1 and L2 are SMD parts and are marked "4.3" and "100" respectively. C1, C2 and C3 are SMD too but they have no markings and I tried measuring them with a lousy multimeter.

Do you think the circuit I drew might do? Can I use a 4.7uH coil instead of 4.3? What would you do if you should start from scratch? Thanks.

Reply to
Slater
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The connectors tend to get flakey after a lot of cycles.

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John Larkin Highland Technology Inc

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jlarkin at highlandtechnology dot com

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

Reply to
John Larkin

Flip it over and resolder all the connections. Never mind if the connection looks good. Just hit everything with a soldering iron.

Shine a flashlight through the PCB. The one in the photo is phenolic, which cracks easily. Look for breaks in the copper traces.

Sometimes the crimps on the wires are bad. Pull on each wire, one at a time. If the wire falls out of the crimp, there's the problem.

Just fix it. No need to redesign it.

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Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply to
Jeff Liebermann

Pull on all the crimp pins.

If its loose, its broke !

Reply to
hamilton

He could have a motherboard that's about to fail. If the elecrolytics are going high ESR, the noise on the power rails can cause problems.

Reply to
Michael A. Terrell

I have a different problem. We put together 3 new quad core PCs. If you use the front connectors ESD freezes the PC.

Reply to
Raveninghorde

I'm not surprised. Ribbon cable for USB 2.0? How long is the cable? I wouldn't connect any USB 2.0 device to that.

Reply to
JW

Just guessing, Did you check the connector pinouts actually match the mainboards headers?

Reply to
Johann Klammer

It's about half a meter, although mine has tinfoil-like shiled and a plastic jacket around it. The tinfoil isn't connected to ground, though.

Reply to
Slater

Does it work OK with USB 1.1 devices (keyboards and mice)? If it does, and gets flaky with 2.0 devices, I would bet on the cable not being apropos for USB 2.0.

Reply to
JW

I can no longer test it because I installed a better and shorter cable with proper shielding and it's working perfectly!

Reply to
Slater

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