Philips 470U (1938)
![470U-front.jpg](470U-front.jpg)
The "U" in the 470U stands for "universal" radio, i.e. suited for AC and DC mains. The 470A is suitable for AC mains, it has has a power transformer and uses a different set of valves. The 470U is a standard uncomplicated superheterodyne receiver with a single IF amplifier and no AF pre-amplifier. Its sensitivity is good enough, though. All the valves are types with a 200 mA heater. The heater voltages add up to 77V. The excess voltage in the heater chain is dropped over a ballast lamp. One has to replace the ballast lamp to change the mains voltage, there is no mains voltage switch. The valve line-up of the 470U is:
The case is in good condition.
The speaker cloth was really dirty (and smelly, too).
The inside, still filthy.
Chassis on work bench, suspended in service frame.
When I tried the radio, it came to life after some turning of the band switch. Incredible! The voltages and currents were well within specifications, so the valves still had ample emission. It got a hint as to why the valves were like new when I fiddled with the volume control. The volume pot cracked and caused the radio to become silent exactly in the range where you should get a decent living room volume. I took a look at the potmeter and saw there was some brown goo that had either leaked out of the pot or into it. It looked like soldering resin and was easy to remove using acetone. It seemed to come from one of the soldering lugs. I decided to take the pot apart and try to clean it. It turned out that an amount of resin had spread across the carbon strip inside the pot, causing an interruption. I cleaned the inside with acetone, too, and put the pot together again. Now the radio played like a sunshine! I think this defect explains the good condition of the case and valves. The pot must have had a drop of excess soldering resin on one of the soldering lugs when the radio left the factory. This must have melted and flowed into the potmeter, causing an annoying crack only shortly after the radio had been purchased. The first owner must have put the radio aside very early on in its lifetime. It may not have been used for 60 years or more, before I fixed it.
The chassis and baffle assembly, some work to do before return to its case.
Baffle with new speaker cloth
The frame is not built to stand on a workbench, so I mounted it in a pair of brackets to handle it. After I received the replacement cloth, I glued it to the baffle. Then I mounted the chassis to the baffle. The chassis is fixed to the baffle with two bolts and two diagonal brackets. Finally, I put the baffle back in place, fastened it with its 6 screws to the case and mounted the knobs. After this, the radio did not only play well, but it looked beautiful, too.
Before: dull dial, dirty bakelite and speaker cloth.
After: shiny case and dial, new speaker cloth.
Copyright © 2004, 2005 by Onno's E-page published 2005-03-18, last updated 2012-09-17