Weak valves in 30s' Philips - UK Vintage Radio Repair and Restoration Discussion Forum

Oskar.B · 24th Apr 2006, 5:59 pm

Newest addition to the collection is a Philips 2534 from 1930, 31. Some links:

Circuit
Outside
Inside

I did some basic work, capacitors in the oven etc

. Checked all resistors and the audio interstage transformer and all seemed fine, so time for testing! Results were not encouraging. HF stage behaved well, detector stage did not. Lots of signal in, not much out. Output valve seemed OK, but HT was reeeally low, only 130 volts. I figured the rectifier must be duff, so I sent all valves to my valve supplier (more of a good friend than supplier actually) for testing. All but the output valve were weak. The detector, replaced by a strange Tungsram valve was useless giving allmost no emission. The HF valve was ok, but not much more. Rectifier was also completly duff, as suspected.

I used to belive sets of this vintage did not see much use. They were quickly made obsolete by new and better designs and I thought these things were played more occasionally, not all day long. This specimen has obviously been played _a lot_. Or did the 30s' valves weaken faster?

I just find it a bit strange. I have never had to replace a lot of valves in the radios I repaired. In fact, the only one I remember replacing is a EL84 with a severe heater cathode leak. Something else usually gives in before the valves.

Anywhay, I have a new rectifier and a good, used, detector valve (Philips original E424) on their way. Will be exciting to see how the radio will perform with fresh valves!

/Oskar

24th Apr 2006, 5:59 pm	#1
Oskar.B Pentode Join Date: Oct 2005 Location: Gargnäs, north of Sweden Posts: 105	Weak valves in 30s' Philips Newest addition to the collection is a Philips 2534 from 1930, 31. Some links: Circuit Outside Inside I did some basic work, capacitors in the oven etc . Checked all resistors and the audio interstage transformer and all seemed fine, so time for testing! Results were not encouraging. HF stage behaved well, detector stage did not. Lots of signal in, not much out. Output valve seemed OK, but HT was reeeally low, only 130 volts. I figured the rectifier must be duff, so I sent all valves to my valve supplier (more of a good friend than supplier actually) for testing. All but the output valve were weak. The detector, replaced by a strange Tungsram valve was useless giving allmost no emission. The HF valve was ok, but not much more. Rectifier was also completly duff, as suspected. I used to belive sets of this vintage did not see much use. They were quickly made obsolete by new and better designs and I thought these things were played more occasionally, not all day long. This specimen has obviously been played _a lot_. Or did the 30s' valves weaken faster? I just find it a bit strange. I have never had to replace a lot of valves in the radios I repaired. In fact, the only one I remember replacing is a EL84 with a severe heater cathode leak. Something else usually gives in before the valves. Anywhay, I have a new rectifier and a good, used, detector valve (Philips original E424) on their way. Will be exciting to see how the radio will perform with fresh valves! /Oskar __________________ Old electronics smell better! http://gargnas.net