Anybody feel like discussing Old Mopar/Motorola hybrid AM radios?
Sorry for the delay, Darthomas. Here is the cover page from the service manual, the schematic of the deluxe model that has an RF amplifier stage, and the top and bottom views of the chassis.
I'll pull the radio out of my car and start troubleshooting it soon. If any of the space-charge tubes are bad, I wonder if I will have any problem finding them? For that matter, I wonder if I have the proper cards for my cardmatic tube tester in order to test these tubes? (Haven't checked yet.) It might be pretty hard to find a tube tester that will test these if I can't use my cardmatic.
Darthomas, what do you make of this "placir chassis" stuff; i.e., is this any different from the usual practice with circuit boards that devote one side of the board to a ground plane?
"Plated Chassis Board Description - Motorola's placir chassis has plating on both sides of the chassis board. The exposed side contains the actual circuit connections while the plating on the component side of the chassis board provides a convenient chassis B- (ground) return for components and circuit wiring. Plating on the component side also provides shielding between the top and bottom of the unit similar to a metal chassis which incorporates hand wiring. All B- connections are carried through the placir chassis in multiple paths to the B- side. This insures a good low resistance return path. Four separate and independent paths are provided to ground. Refer to "Plated Circuit Chassis Servicing Techniques" manual (Motorola Part No. 68P636536 for information pertaining to servicing the plated chassis board."
Sorry for the delay, Darthomas. Here is the cover page from the service manual, the schematic of the deluxe model that has an RF amplifier stage, and the top and bottom views of the chassis.
I'll pull the radio out of my car and start troubleshooting it soon. If any of the space-charge tubes are bad, I wonder if I will have any problem finding them? For that matter, I wonder if I have the proper cards for my cardmatic tube tester in order to test these tubes? (Haven't checked yet.) It might be pretty hard to find a tube tester that will test these if I can't use my cardmatic.
Darthomas, what do you make of this "placir chassis" stuff; i.e., is this any different from the usual practice with circuit boards that devote one side of the board to a ground plane?
"Plated Chassis Board Description - Motorola's placir chassis has plating on both sides of the chassis board. The exposed side contains the actual circuit connections while the plating on the component side of the chassis board provides a convenient chassis B- (ground) return for components and circuit wiring. Plating on the component side also provides shielding between the top and bottom of the unit similar to a metal chassis which incorporates hand wiring. All B- connections are carried through the placir chassis in multiple paths to the B- side. This insures a good low resistance return path. Four separate and independent paths are provided to ground. Refer to "Plated Circuit Chassis Servicing Techniques" manual (Motorola Part No. 68P636536 for information pertaining to servicing the plated chassis board."