Hi All, My EKCO PB506 has been in the workshop for a long while tucked away, Which is a shame because when it was working it was brilliant. It developed an intermittend fault whereby I wouldn't be able to pick up stations (just a mains hum)
I thought it would have been the EBL1 and ECH3 knowing how unreliable side-contact valves are but I am beginning to thing it isn't, It was mostly re-capped two years ago. I say mostly as the remaining waxies all measured fine!
The amp is certainly working, as I can feed sound into the gram sockets. I'd like to think there is some life in the IF as I can connect an aerial and get a small "click" but alas no stations on any bands... I don't think the oscilliator is alive as I did tune a MW radio nearby and got no oscillation noise. Ive also tried substituting the valves.
It has pushbuttons but i'm struggling to find any voltage on the pushbutton tuner! Of course, MR E.K.Cole decided he would not release a circuit diagram which subsequently never made it to the internet, So all I have is a rather vague traders sheet..
Definitely sounds like a dry solder joint around the mixer valve. Or possibly a problem with the valve base. I have only ever come across side contact valves in one radio, they did not seem very reliable, a very small contact area. Does wobbling the valve cause it to come and go? You could tap around all the solder joints under the chassis with a plastic stick to see if it crackles. Then I would go around and re-flow all the solder joints to make them nice and wet looking.
Mike
I have only ever come across side contact valves in one radio, they did not seem very reliable, a very small contact area.
...and that is the reason why a good many side contact valves were replaced with their octal equivalent...in your case an ECH35 and an EBL31 (which will also need a smaller top cap connector).
I say mostly as the remaining waxies all measured fine!
...measured how?
It's possible if they are in low voltage circuits that you may get away with not replacing them...cathode decouplers for example, but any used where there is a sniff of HT are probably breaking down under load.
Definitely sounds like a dry solder joint around the mixer valve. Or possibly a problem with the valve base. I have only ever come across side contact valves in one radio, they did not seem very reliable, a very small contact area. Does wobbling the valve cause it to come and go? You could tap around all the solder joints under the chassis with a plastic stick to see if it crackles. Then I would go around and re-flow all the solder joints to make them nice and wet looking.
Will do, no the valves have been moved every which way possible! I even found two paxolin washers to put under the valves to raise them up a bit and see if it was bad contact and nothing so I had best get the soldering iron out. Isn't it amazing to see how bad we all used to be at soldering and fitting components... this was one of my earlier sets... 
