Over the lifetime of the BK series, we’ve had some issues dealing with the display, and temperature readout. There would be an intermittent fluctuation of the temperature both on the display, and in the heater portion. I had not determined the root causes for some time, and it seems my predecessor had not either. After discussing with my manager that our European partner Circuitspecialists.eu had not experienced this issue, a light bulb went off. The one thing I hadn’t thought of, nor tried was to clean the contacts and reseat the ATMega16 on it’s socket, that controls the unit. I attempted this fix on a unit currently under repair, and it does seem to have fixed the issue. Please contact me if this isn’t a fix after all.
To perform the fix, remove the four front screws holding the front panel.
Next is to remove the screws on the backside of the board, desolder the two points of wire, and disconnect the JST connectors.
Next it to remove the MCU from it’s socket.
Once you’ve done this, use a good solvent such as our contact cleaner from Mg Chemicals and clean the socket contacts then reseat the MCU firmly back into its socket. Reassemble and you’re done. Please let me know if this doesn’t fix the issue and still remains.
I also dumped the binary for the MCU in case anyone needs to reprogram it. You can find it on our GitHub at https://github.com/circuit-specialists/BK8K.