Oceanic 'Trafic' transistor radio

serial number 666153 

Oceanic Trafic Medium [PO] and three short [CO] wave band portable transistor radio in blue Rexine covered wooden case and cream plastic fascia. Six transistors: osc and 2 IF stages, and driver and two push pull output. Sockets for earphone and external aerial for medium waveband. It has a round 4 ohm, 4 inch loudspeaker. This dirty little radio was one of three purchased at auction for 5 in 2012. When it was acquired the exterior was very dirty, the inside full of dust, the scale was wrinkled and caught on the pointer, the carrying handle was missing and the output was weak and distorted. Oceanic Paris, France 1961/2

Inside view, showing years of dust and wrinkled scale

I established that the front end of the set was OK by feeding the signal across the volume control into a separate amplifier and loudspeaker. I found that DC potential on the output capacitor was only 3 volts [should be at half the supply voltage] and suspected that one of the output transistors may be at fault. These were removed, tested and found to be OK. Without the transistors in place the potential was correct. I surmised that the fault must therefore lie in in the transformer. Not knowing which terminations were which I traced out the tracks on the printed circuit and established that one secondary section of the transformer was open circuit. Fortunately, this was due to a break in the external connection between the circuit board and the winding so readily repaired. C21, the output capacitor was replaced as it only measured 25 mFd when tested.

oceanicscale.jpgI was not able to flatten the scale sufficiently so I scanned it and made a paper reproduction which was glued in its place.

The radio is built as three separate sub assemblies

This unusual battery pack with 4 pin connector is slightly smaller than a modern PP9 battery.

Enlarged version of schematic diagram stuck to the inside of the wooden case.

My little sketch of the amplifier module