This is the continuing story of my R4B that drifts and wiggles in frequency and stops oscillating. My last installment I found a solder joint that was not soldered to the ground plane.
After that the PTO would still wiggle and stop oscillating and when I pressed on the end of the PTO cover the PTO would start oscillating again.
Taking the cover off and pressing the PTO circuit board I could make PTO stop and start oscillating. Moving the circuit board and measuring the ground at the 6.8K ohm resister, I found that the ground was at 10.0 volts when the PTO stopped oscillating.
I followed the ground to the front of the PTO and there is a small jumper wire between the main PTO circuit board and the vertical PTO circuit board. I found that measuring the ground connection on the vertical PTO circuit board would not change when I pressed on the PTO circuit board but when I measured the ground on the main PTO board it would. On closer inspection the ground solder connection on the main circuit looked like that the solder had not made complete contact with the wire or had come lose.
I re-soldered and inspected the joint again and the solder had rapped round the short ground jumper.
I gently pressed on the circuit and the PTO continued to oscillate. I have put the receiver back together. The PTO is stable and continues to oscillate.
Lee KI6OY P.S. I hope that this helps someone else. _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
