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HP 50g & SD Cards: Performance, Format, Notes
09-03-2016, 10:33 PM
Post: #90
RE: HP 50g & SD Cards: Performance, Format, Notes
(09-03-2016 10:08 PM)JDW Wrote:  Gentlemen, thank you for your replies.

My 50g is at the office, where I have my tools, so I cannot touch it until Monday, Japan time. For now, I would like to reply to Vtile regarding the "CSV" data. I copied that text and pasted it in TextWrangler, then saved it as a *.csv file, but when I open that file in Excel, it appears simply as imported text that looks exactly the same as the mess we see in your post here. So could you please open Excel on your computer, then take a screen shot, then post that screen shot? I ask this because I cannot make sense of the data you presented, nor can I tell if in your test you discovered that R67 is truly the WP line or not. (I did not test R67 when I made my video.)
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.

So, Vtile, if you answer the questions above, I will be well equipped to perform further checks on my 50g this Monday, at which time I will report back here.
Hopefully you find the reason for the problem.
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RE: HP 50g & SD Cards: Performance, Format, Notes - Vtile - 09-03-2016 10:33 PM

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