HP 50g & SD Cards: Performance, Format, Notes
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09-03-2016, 10:33 PM
Post: #90
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RE: HP 50g & SD Cards: Performance, Format, Notes
(09-03-2016 10:08 PM)JDW Wrote: Gentlemen, thank you for your replies.Here are my findings as an image. I did though that you might need some reference for your measurements. I hope I didn't make any fools mistake on this. The R67 did to me seem to be somesort of pulldown resistor, since the trace branches to throught the board connecting hole and I have not taken the board off. I'll leave the further measurement to you. (09-03-2016 10:08 PM)JDW Wrote: You mention 17:50 in my video, but that is the point at which I showed my continuity check between R68 and the SD card metal frame. Please explain what specific "interesting text on the PCB" that you were talking about.That didn't actually relate to the current problem at all. The board have markings that indicates that same PCB is used for 50g, 39g and 40g from "current" production. (09-03-2016 10:08 PM)JDW Wrote: As to whether the resistors are faulty, I need to of course verify that on Monday, but in my years of experience, I would say "it's unlikely." I see no burn marks nor smell any evidence of component burning, which is usually what causes resistors to fail. (Another common reason for non-burned resistors to fail are solder balls or other soldering defects at the time of manufacture, which are not present in my calculator from what I can see.) Moreover, those resistors are there as simple protection mechanisms since the SD card interfaces with the outside world. You want to use resistors like that to prevent a dead short which could otherwise harm the MCU.Hopefully you find the reason for the problem. |
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