Philips B4X92A (1957)

The Model

This is a tabletop radio manufactured and sold by Philips Belgium in 1959/1960.

It receives Long/Medium/Short Wave AM plus FM.

The Object

Like most of my radios, I found it at the Het Goed thrift store in Eindhoven. It cost 15 euros in February 2022.

The cabinet had the usual scratches and stains in the wood, but nothing too bad. The grill cloth was torn, showing the speaker behind it, but the speaker itself was undamaged. It was also missing the two front "feet", which makes it tilt frontwards. The dial pointer was stuck, but everything else was in good condition.

The Restoration

Restoration started in April 2022. A little bit of lubrication took care of releasing the dial pointer. The radio had a number of electrolytics and "bumblebee" caps that begged replacement. The EM84 "magic eye" tube was spent, and I swapped in a new one. At this point the radio played normally.

However, the magic eye worked only when the AM bands were selected. On FM it just kept open. When FM is selected, the grid of the EM84 tube is fed via the FM detector/discriminator (using two diodes from the EABC80 tube), and was supposed to measure voltages up to -22V (although in practice I observe max around -7V in other radios, but still enough to close the eye), but in this radio it measured at max -0.3V, even with strong stations.

I even tried asking about this problem in the Netherlands Forum for Old Radios, but unfortunately could never work out what was causing it. I've tried replacing many capacitors/resistors, the EABC80 tube, the 470k capacitor on the EM84 base, tune the IF transformer, all to no avail.

Philips B4X92A (1957)

The Model

The Object

The Restoration

The Result