Crystals wont oscillate
Posted: Tue Jun 06, 2017 12:58 pm
I have a setup where my FV-1 chip reside on a daughter-board together with the clk crystal, crystal cap and the decoupling capacitors. This board connects with header pins to a "main"-board which houses the power regulator (LM1117), more decoupling capacitors and all other necessary circuitry for my project (analog mixer, FV-1 associated pots and switches, etc.). The circuitry on both the main-PCB and daughter-PCB is verified as working. I've built 3 units and they all work as intended without any issue.
However... I built 9 daughter-boards in total of which just 4 are working. The FV-1 chips are sourced from ProFusion while the crystals are sourced from BitsBox and Tayda Electronics. The FV-1 chips were soldered using solder flux. The boards were then cleaned thoroughly using a Q-tip soaked in acetone. I've not been able to detect any broken connections of short-circuits on any of the daughter-boards. The daughter-boards were tested by connecting them to a verified main-board. When any of the non-functioning daughter-boards are connected the clip LED (mounted on the main PCB) is constantly lit, leading me to believe the issue could be related to the clk crystal not starting to oscillate.
Initially only 3 boards worked as intended. For one of the non-working boards I swapped the crystal (Tayda sourced) for another (BitsBox sourced) which solved the problem. However when I tried this fix on another non-functioning board the issue persisted. Two of the daughter-boards with crystals from Tayda initially worked, but when retested would not start up (???). Also the one board with a Tayda sourced crystal that does work takes about 2 seconds to start up, and one of the non-functioning ones sometimes starts up after 10-15 seconds. Generally speaking I feel the boards are acting unpredictably, and I feel very uncertain to what is the definite issue. I'd like to pin the malfunction on the Tayda sourced crystals, but as stated one of the boards with a BitsBox sourced crystal also isn't working.
Could the issue be that I haven't placed the crystal and 22pF cap close enough to the associated legs on the FV-1? There is approximately 5-6mm of copper separating the actual bodies of the crystal and the FV-1. Any suggestions? I'm about ready to pull my hair out..
Daughter-board schematic and PCB:
However... I built 9 daughter-boards in total of which just 4 are working. The FV-1 chips are sourced from ProFusion while the crystals are sourced from BitsBox and Tayda Electronics. The FV-1 chips were soldered using solder flux. The boards were then cleaned thoroughly using a Q-tip soaked in acetone. I've not been able to detect any broken connections of short-circuits on any of the daughter-boards. The daughter-boards were tested by connecting them to a verified main-board. When any of the non-functioning daughter-boards are connected the clip LED (mounted on the main PCB) is constantly lit, leading me to believe the issue could be related to the clk crystal not starting to oscillate.
Initially only 3 boards worked as intended. For one of the non-working boards I swapped the crystal (Tayda sourced) for another (BitsBox sourced) which solved the problem. However when I tried this fix on another non-functioning board the issue persisted. Two of the daughter-boards with crystals from Tayda initially worked, but when retested would not start up (???). Also the one board with a Tayda sourced crystal that does work takes about 2 seconds to start up, and one of the non-functioning ones sometimes starts up after 10-15 seconds. Generally speaking I feel the boards are acting unpredictably, and I feel very uncertain to what is the definite issue. I'd like to pin the malfunction on the Tayda sourced crystals, but as stated one of the boards with a BitsBox sourced crystal also isn't working.
Could the issue be that I haven't placed the crystal and 22pF cap close enough to the associated legs on the FV-1? There is approximately 5-6mm of copper separating the actual bodies of the crystal and the FV-1. Any suggestions? I'm about ready to pull my hair out..
Daughter-board schematic and PCB: