22-12-2013, 07:20 PM
Ok, I think this has been mentioned before but you need to check the RF tuning coils and their coupling coils to the mixer, check out MW first.
First of all, according to the schematic when MW is selected both the MW RF tuning coil and the LW RF tuning coil are connected together in parallel, you need to verify that neither of those coils has gone high resistance or open circuit and that they are indeed being connected in parallel when MW is selected, if that checks out ok then the next step is to check for continuity between both ends of those two RF tuning coils and the chassis, you should normally get a very low resistance reading from either end of those RF tuning coils when MW is selected.
If that checks out ok then the next thing is to check the continuity of the MW coupling coil to the mixer when MW is selected, this can be checked by measuring between the switch side of C3 and the chassis, again it should be a very low resistance reading. If you can do that then report back with the results to give us all an idea.
Lawrence.
First of all, according to the schematic when MW is selected both the MW RF tuning coil and the LW RF tuning coil are connected together in parallel, you need to verify that neither of those coils has gone high resistance or open circuit and that they are indeed being connected in parallel when MW is selected, if that checks out ok then the next step is to check for continuity between both ends of those two RF tuning coils and the chassis, you should normally get a very low resistance reading from either end of those RF tuning coils when MW is selected.
If that checks out ok then the next thing is to check the continuity of the MW coupling coil to the mixer when MW is selected, this can be checked by measuring between the switch side of C3 and the chassis, again it should be a very low resistance reading. If you can do that then report back with the results to give us all an idea.
Lawrence.
