Hi,
I’m at the calibration phase and I have the same issue as in some of the other posts that when I power on the green led flashes in the 2 4 2 sequence. I tried the troubleshooting from the other posts and have disconnected the bypass switch. When checking the resistance between pin 4 on microcontroller and bypass round pad it measures 1.5. Any suggestions?
Nicholas,
Unfortunately, this sounds like the microcontroller may have been damaged. But when you measure the resistance between pin 4 on the micro and the round pad of “Tap sw”, you get 1.5 what? What units? What about when you measure the continuity between pin 4 of the micro and the square pad of the “tap sw”…are they connected?
-Brach
Hi Brach,
Thank you for your reply. Checked continuity. I have continuity between pin 3 and round pad of bypass switch and between pin 4 and tap switch. Had faulty multimeter so disregard previous readings. Resistance between both pins an pads is 0.5 ohms. I have been using an antistatic mat during assembly to make sure the chip didn’t get damaged. Been servicing pcb’s on our studer A820 MCH for last while and haven’t had a chip fail yet. Slightly perplexed
Bummer. So, i guess you need a new microcontroller, or you can try to re-flash it (via our updater app and an USBtiny ISP, if you have access to one). That is too bad. I’m perplexed too about why that pin is so fragile….i’m sorry. I know it has something to do with the internal architecture of the chip. Anyway, contact us via email about getting a new IC. Our address is info “at” zeppelindesignlabs “dot” com.
Once again, I’m sorry about this fragile IC.
-Brach