alfista wrote: > Sorry for being vague, shouldn't have formulated a question before my > first cup of coffee. I was thinking of the model of the memory device. > But from your answer I can deduce roughly what kind of Flash it is. > Flash of that generation usually have pretty much no data retention > problems, but heat can accelerate the process so maybe using a hotplate > for soldering could potentially be an issue. > Never had a problem with data loss in normal circumstances, some 15 > years ago I came across a few memories where single bits had been > flipped, but that was on outdoor equipment where we suspected lightning > could have been involved.
Ah, all right. So what Logitech used here, as far as I found on my bench, is either Spansion S29AL016D90TFI02 or AMD AM29LV160DB (-90EC) Both are 16 megabit CMOS 3V 48-pin TSOP and probably interchangeable. Infineon has another model that might also be compatible but I have never checked, so you are on your own trying, the model is Cypress S29AL016J. What I think might be the reason is not the memory chip itself or its exposure to outside influence during the repair but rather a malfunction somewhere in the OS. I mean the Squeezeboxes are capable of downloading and flashing their EEPROM themselves, and store configuration data dynamically (e.g. the Wi-Fi SSID, the WPA password, the LMS server's host name if an LMS is being used, and some local config like display-related stuff). The part that is dedicated to writing to the Flash EEPROM for these purposes might be kicking in at some unexpected moment and go rogue. Just a tiny fraction of that would be enough to brick the device. Which also means this issue might come back at any time. What is interesting though is that a device bricking itself is happening only after years of flawless operation. I would not suggest that the Squeezeboxes were timebombed though. Logitech does not have anything better to offer nowadays so it wouldn't serve them to have the previous generation of devices kill itself. Could be just a glitch somewhere in the firmware that was overlooked. Another theory is that the Flash is written too frequently so the flash cells get weaker. Unlike SSDs with SMART capabilities, these chips don't monitor themselves and there is no way of knowing how reliable the memory cells are. Also, there is no load balancing to ensure that all cells are used so they all age at the same rate. There may be test equipment to find out detail but I guess nobody has something at hand that can evaluate the quality of a Flash chip, and not destroy it any further along the way. In case of an aged chip I would expect that reflashing has issues, for instance, verifying a freshly written image should result in some errors if cells don't accept the new data as they should. But maybe the cells recover (at least for a time) when they are erased and then completely reflashed. It's too early now to say that reflashing the original EEPROM is the cure forever. If the chip is aged, the device might just be on the edge of dying again soon. I will keep watching this. At least this might explain why the devices fail this way only after more than 10 years. I believe the Squeezeboxes write to Flash whenever something is changed about the basic configuration (which requires to go to the Settings menu or even to the setup menu), and also when there are changes about display brightness, "now playing" info screen, volume etc. Of course these are all assumptions but if I were the developer dedicated to storing dynamic configuration values to Flash memory, I would try to do that as rarely as possible, for instance when the device changes mode from on to standby. In that moment, I would collect all config data that is relevant for permanent storage, compare it to the values being in the config storage already, and only writing the difference. But who knows if the Squeezebox firmware is actually that smart. Unfortunately, the address where the config is held is always the same so, assuming there is no wear balancing, the same Flash cells are written over and over again, which might actually be a problem. Maybe the designers didn't care much about Flash memory wearing at all. If so, how could they have known that these systems get so popular and will be in use for so long? I remember Tesla was in the news about Flash memory in their cars which ages rapidly because of the permanent camera surveillance and everything being recorded. It seems that they forgot that Flash isn't lasting forever, and over-used it heavily. But that's a different amount of data and bandwidth. Squeezeboxes are doing nothing in comparison. Still, it's a thought. >From that perspective it might be best to use entirely new chips instead of reusing the original ones... But let's keep discussing here. It's very interesting to include your opinions on this, guys. I'm far from being an expert here. PN me if your Boom / Classic / Transporter display has issues! Blog: https://www.blogger.com/blogger.g?rinli=1&pli=1&blogID=5053304027701850753#allposts ------------------------------------------------------------------------ JoeMuc2009's Profile: http://forums.slimdevices.com/member.php?userid=23131 View this thread: http://forums.slimdevices.com/showthread.php?t=117140 _______________________________________________ discuss mailing list discuss@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/discuss
