Vintage Cassette Radio Recorder – National Panasonic RQ 432S schematic, layout and dial cord setting.
The main fault that can occur to this set is the tuning drift as climatic change. The inductance of TR54 and or TR56 changes. Replace them if this type of fault occurs.
At the amplifier stage, C19 and C20 [capacitors connected between collector base of the output transistors] may get leak. Resulting distorted audio output. They have used steroflex capacitors there. I’ve replaced both of them with disc ceramic [250VDC] type, and going fine.
The C34 [1000MFD-10V] should be checked for its capacitance. It is best to replace it. Sound distortion can occur if this capacitor is damaged.
C32 [220MFD 10V] can also be problematic. Replace it.
I own this model set, which bought at mid of 70s, I presume, is working fine till time. There is no more problems can occur to this set.
Amplifier section schematic
