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COBRA 2000 HELP
- Thread starter BAGEBOY
- Start date
Do you know where the two bias-test jumper wires are? Don't have a picture handy.
Unplug the end of each of these where they plug into the circuit board.
See if keying the mike still causes this symptom with both wires unplugged.
Would tell us where to look next.
73
Unplug the end of each of these where they plug into the circuit board.
See if keying the mike still causes this symptom with both wires unplugged.
Would tell us where to look next.
73
I unplugged the purple wire and it stayed on when plugged back in it went back off when I key on ssb
Means the purple wire the section it goes to in the back, has a problem, from a blown final - dead short - onto a blown diode (bias type) open popped like a fuse - you need to investigate, look for soldering issues, else parts (possibly more than one since you can TX on AM but not SSB) needs to be replaced - the purple wire is a feed from the AM / SSB mode switch power branch - one side goes to the AM Regulator (TR41 and TR42) routes to the front panel - along with wires from the Power choke to that mode switch - then goes back to the power choke, using TP "stems" and routes from there to their Driver or Final sections.
IF work has been done previously - the section that purple wire affects, may need to be rebuilt or at least ohmed-out using a DVM in Continuity-setting for dead short checks as well as Ohmic and Voltage checks afterwards in AM mode - then in SSB - with the power off if necessary to prevent damage while checking for those shorts..
IF work has been done previously - the section that purple wire affects, may need to be rebuilt or at least ohmed-out using a DVM in Continuity-setting for dead short checks as well as Ohmic and Voltage checks afterwards in AM mode - then in SSB - with the power off if necessary to prevent damage while checking for those shorts..
