alexconway Posted October 12, 2021 Share Posted October 12, 2021 Hi there, I have an AD2 which just stopped working. Windows complains "device descriptor request failed". I looked around the board and have found a cracked compoment under the USB connector. It looks like a ferrite bead. Does anyone know what I could replace it with? Thanks, Alex Link to comment Share on other sites More sharing options...
0 attila Posted October 12, 2021 Share Posted October 12, 2021 Hi @alexconway First, to see if the board is alive you could short it. For more detail see the following post: Link to comment Share on other sites More sharing options...
0 alexconway Posted October 12, 2021 Author Share Posted October 12, 2021 (edited) Hi @attila I shorted it and now windows doesn't even register an error for it. There is definitely 5V getting to it. When I unplug it and measure resistance from Vbus to GND I get a reading of 64Ohms. And pin 2 of the USB Micro B connector measures 1Ohm to GND, but pin 2 is open. Are there any other protection devices that might be shorted? Otherwise it looks like the USB receiver is busted. And, to add to my misery, the port on the USB hub I was using no longer works. Thanks Alex Edited October 14, 2021 by alexconway more info Link to comment Share on other sites More sharing options...
0 alexconway Posted October 20, 2021 Author Share Posted October 20, 2021 (edited) I have now replaced the FT232H, and it appears as a RS232 COM port on device manager, VID 0403, PID 6014 I started up Waveforms and tried to use the Device Fix, but it fails with the message "FT_EE_Program failed (12)" Is there any info about what error 12 is? I have checked that the EEPROM (the 6 pin SOT23 in my photo) has 3V3 power going to it: all pins are at 3V3 except the gnd pin and clk (which I have checked is not shorted to GND) Any pointers?... Thanks Alex Edited October 20, 2021 by alexconway spelling Link to comment Share on other sites More sharing options...
0 attila Posted October 20, 2021 Share Posted October 20, 2021 Hi @alexconway The error is FT_EEPROM_WRITE_FAILED = 12 Unfortunately I don't think it worth to continue the troubleshooting, likely other ICs are damaged as well. Link to comment Share on other sites More sharing options...
0 alexconway Posted October 21, 2021 Author Share Posted October 21, 2021 (edited) I have probed the Eeprom and at power up there is activity on Chip select, but clk and data both remain high - not due to being shorted to 3V3 but because of the 10k pull-ups. This is on the pins of the FT232HQ and the Eeprom. It's tantilisingly close... As to how I broke it: I was using the analog inputs set to 100mV/div, differentially measuring two dc voltage outputs that were 0.25V - 1V. The AD2 GND was also connected to the GND of the test circuit. The circuit generating these outputs was powered from 18V bench supply - with a fair amount of transient current ability and a floating output, so GND was connecting thru the AD2. I accidentally shorted something to something - I think I left it powered and put my grounded soldering iron on the 18V. Effectively I forced the 18V of the bench supply to be GND and the GND to try and be -18V. The result was as above. I'm guessing that at 100mV/div there is still attenuation in the analog input circuit, so I don't think the current flowed there, so it must have been between the AD2 input GND and the soldering iron GND, thru the powered and grounded USB hub. Cheers Alex Edited October 21, 2021 by alexconway spelling, clarification Link to comment Share on other sites More sharing options...
0 alexconway Posted November 9, 2022 Author Share Posted November 9, 2022 One year later and I can now buy geniune FT232H, rather than take a chance with one desoldered from an Ebay hobby board. And a replacement genuine FT232H fixes it, as far as I can tell at the moment... Cheers Alex Link to comment Share on other sites More sharing options...
0 attila Posted November 10, 2022 Share Posted November 10, 2022 Hi @alexconway I'm glad to hear that. Thank you for the update. Link to comment Share on other sites More sharing options...
Question
alexconway
Hi there,
I have an AD2 which just stopped working. Windows complains "device descriptor request failed".
I looked around the board and have found a cracked compoment under the USB connector.
It looks like a ferrite bead. Does anyone know what I could replace it with?
Thanks,
Alex
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