hi @badger2 -- glad this thread was helpful, and i hope you were able to figure out your issue with the buttons.
i do have another update -- shortly after putting the dehydrator back in service (the reassembly was a pain), it stopped working again, same symptoms. i had had my son learn about soldering in replacing the D7 diode, and he'd cooked the PCB a bit too much, so i'd had to scrape some of the insulative sheath off the trace and solder to that, then glue it in place -- i assumed this had been a weak connection and had failed.
however, i pulled it all apart again, only to find that the replaced D7 diode and its connections tested fine. instead, the previous diode in the voltage-reduction chain was blown (ie. D6). so i replaced this one as well, this time using the long legs of the diode to jumper over the traces to add redundancy, and put it back together -- and it didn't work, no life in the control panel.
so i started testing voltages -- it was the full 15VDC after the FWB, but then dropped 10V over the next diode (D5), so that by the time it came out the end (D9) it was around 3V, which i'm assuming is just about too low to activate the control panel.
however, while i was poking around checking voltages, the board suddenly lit up. now it's working fully as expected. voltage drop across the series of diodes is about 3.5VDC. each is ~650mV.
so... any ideas what might be going on?
is this a sign that all the diodes in that chain are on their last legs and should be replaced? (but do diodes have a failure warning mode like that? i thought they didn't...)
or is it a sign that there's some other problem somewhere that's causing diodes to blow? (like maybe spikes of voltage from something?)
or could it be that my hackish soldering job is causing intermittent problems? (like maybe a poor connection that was adding to voltage loss?)
any thoughts very welcome!
i'm going to try running it for a while and seeing what happens...
i do have another update -- shortly after putting the dehydrator back in service (the reassembly was a pain), it stopped working again, same symptoms. i had had my son learn about soldering in replacing the D7 diode, and he'd cooked the PCB a bit too much, so i'd had to scrape some of the insulative sheath off the trace and solder to that, then glue it in place -- i assumed this had been a weak connection and had failed.
however, i pulled it all apart again, only to find that the replaced D7 diode and its connections tested fine. instead, the previous diode in the voltage-reduction chain was blown (ie. D6). so i replaced this one as well, this time using the long legs of the diode to jumper over the traces to add redundancy, and put it back together -- and it didn't work, no life in the control panel.
so i started testing voltages -- it was the full 15VDC after the FWB, but then dropped 10V over the next diode (D5), so that by the time it came out the end (D9) it was around 3V, which i'm assuming is just about too low to activate the control panel.
however, while i was poking around checking voltages, the board suddenly lit up. now it's working fully as expected. voltage drop across the series of diodes is about 3.5VDC. each is ~650mV.
so... any ideas what might be going on?
is this a sign that all the diodes in that chain are on their last legs and should be replaced? (but do diodes have a failure warning mode like that? i thought they didn't...)
or is it a sign that there's some other problem somewhere that's causing diodes to blow? (like maybe spikes of voltage from something?)
or could it be that my hackish soldering job is causing intermittent problems? (like maybe a poor connection that was adding to voltage loss?)
any thoughts very welcome!
i'm going to try running it for a while and seeing what happens...