[julie_m]

Originally Posted by indigo.girl

I started to trouble-shoot before your posts Julie and Lawrence....this is what I found...

Excellent stuff! Just don't be afraid to stop and ask, if you get out of your depth.

Originally Posted by indigo.girl

To start with the lamp limiter bulb didn't glow at all suggesting no current was getting through to the radio at all. So I checked the on/off switch that's part of the volume pot. I could measure 85V AC across the L and N going into the switch but zero volts coming out no matter how I turned the dial. So I presume that switch is broken.

A reasonable assumption so far ..... Sometimes they come to life with a bit of exercise; but for now, bypassing it is fine. 85V sounds a little bit low, though; it would leave 145V for the bulb, which would light it quite brightly though obviously not full-on. Never mind; perhaps that's an error.

Originally Posted by indigo.girl

I decided then to bypass the switch and so I connected the switch outputs to the mains input. Still nothing but the lamp limiter bulb does faintly glow now.

That's a good sign. It means some power is going into the set. What wattage bulb are you using?

Originally Posted by indigo.girl

There are lots of wires connected into the transformer that I can't identify but there are two output wires than connect directly to a small bulb that illuminates the wavelength selector screen.

There will be various connections to the primary windings, which can be rearranged so as to give different turns ratios to suit different supply voltages. The Manufacturers' data shows the connections for each voltage setting, but you need only go there if you suspect a transformer fault.

Originally Posted by indigo.girl

I measured across here and there is zero voltage across these outputs which at first suggested to me that there was something wrong with the transformer since I was not getting an output. However, I can now see that all three valves are beginning to glow. (AZ31 the rectifier is not) so something must be getting through.

Probably just a bad connection of one of the meter probes, or something. It happens sometimes. All you can do is keep trying.

Originally Posted by indigo.girl

EDIT: Upon further testing I can now measure 4V AC across the screen bulbs - no glow but I'm wondering if thats because 4V AC is too low and perhaps the bulbs may work when I remove the lamp limiter (Not going to do that yet until I'm sure its OK to do so).

Or it's quite possible the bulbs are just dead, or not making good contact ..... They should light, even if a bit dimly, at 4V.

The AZ31 (rectifier) valve has its own separate winding on the transformer for its filament, which will be at HT potential when the rectifier has warmed up. Carefully remove this valve and measure the resistance between pins 2 and 8. (Should be very low, 1 Ω or even dead short.) With the rectifier still out, switch your to AC 20V range, put your probes on pins 2 and 8 of the rectifier's socket and power up the set. Nothing much will happen (since it's not going to get any HT) but you should measure 4V AC there.

If the rectifier filament is open-circuit, don't worry too much; there is a "cheat" we can do in the meantime while waiting for a new one to arrive, which will allow you to continue testing the set.