NP-41 Emulator (may be)
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12-22-2017, 01:46 PM
Post: #351
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RE: NP-41 Emulator (may be)
(12-22-2017 02:15 AM)Egan Ford Wrote:Hi Egan,(12-21-2017 04:17 AM)Chris Chung Wrote: Egan, may try to reinsert battery, and press X key if display is blank. If the charge pump failed, the X key in key test mode will toggle charge pump on and off. Toggle off charge pump makes the unit to use Vcc for LCD biasing. Only other thing you can try is to bootload firmware, although I think it's more of hardware issues based on the fact that the cold-start screen also does not show. If you have USB-Serial please try new firmware. Otherwise I can only do a refund or a replacement unit. For a replacement unit, there will be a longer wait. For the new 2 units I assembled (Dec 12 and 18th) one of them already failed and I had to re-flow the chip to fix it. And It now got a problem which one of the 1st match had. I.e. locked up / freeze at MEMORY RESET, which is due to FRAM corruption. I had bootload firmware again to make it work. But this is not acceptable. I had some clues now but no solution. For some reason the internal Vcc voltage measured is way less than my multimeter tells me. I.e. 2.88V vs 2.05V on battery. This somehow leads to FRAM corruption. My good unit have the internal Vcc voltage close to the real voltage. I suspect some of the units failing have the same symptom. A temporary fix would be to bootload firmware again. This has to be investigated. I may not be able to deliver good units in 1 / 2 weeks, as if they are not reliable, it benefits no one except the postman. Even the working order units may fail sometime. Please let me know if you are able to wait longer for a replacement (say 5-6 weeks) or you want to have a refund. I am ordering (hopefully today) new PCBs which should help the current problem. After studying design notes and such. I am moving the charge pump capacitor close to the chip and add ground plates around it. On the top side, the PCB will have a lot of ground plates to help w/ noise. Also reduce optional component to reduce trace (say bias resistors for external contrast control). We will see if this can eliminate the stability problem. Also working on firmware for FRAM protection and problem detection. |
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