A friend who saw my radio collection on facebook, gave me this absolute gem, which belonged to her hubby's grandfather, on condition, I take a video of it working for him.

I was hoping for an easy fix, but it seems I've had my share of those already.

I brought it home, knowing it apparently used to work, but no longer does,.so without plugging it in, I simply replaced all of the caps and all of the wires that all the rubber insulation looked crumbly. I then powered up, slight hum through speaker regardless of volume, all valves and dial lamps lit up, but no volume response or sound, no stations.

I checked voltages, about 278 from between the electros, down to the coils and at least 170v- 275v at, at least one of each valve pins. It has four valves.

I thought maybe the speaker transformer oc as my multi-meter didn't beep for continuity through the primary, just the secondary, however when I cracked the 9v battery over the primary I got a faint tick from the speaker and a delightful electric shock from the 9v battery as I had the bare wires in my fingers, like an induction coil effect! Not sure, I'll need to check all of the resistors next and try and obtain a schematic, once I find the model number! It's a real good looker, I'm sure it'll sound good too!!!

Photos?

Yes to Photo's. I consider it to be an exercise in poor methodology and a poor use of time to go through a radio and replace the old wax paper caps & not make a decent effort to check the resistors.

By not doing this you risk doing damage, & risk frustration, when you have to go back & replace the one or several that caused the set not to work. It's a reflexed set. Astor made a lot of them.

If this has a 6V6 then the grid resistors on them have an attrition rate & I normally buy 470K & 50K in big lots as that valve normally kills its & the Kriesler 11-20 I have on the bench is typical of them, where its going out with three original resistors, the rest were all out of spec. A new mains cable as well (Original 2 wire cloth rubber one was still on it... scary).

Not impressed with the previous serviceman's attempt. I didn't bother to power it when I got it. Did today, might get to sort out the cabinet screws (wrong ones) & put it back together by Friday. Chassis is finished.

Post war Astors are notorious for perished rubber-coated wiring. Sometimes you can get away with sleeving the wires with heatshrink.

All Astors have a model designation consisting of 2 or 3 letters followed by a serial number stamped somewhere on the chassis.

Having four valves would narrow it down to these models:

DL, GJ, GKM, HK, HQ, JJ, KL, KK, KM, LS, NJ & QK.

Schematics for these models (except GJ, GKM & KK) can all be found here:

http://www.kevinchant.com/astor1.html

Photo looks like model NS of 1951 with 6U7G, 6J8GA (or X61M), 6U7G, 6AV6, 6V6GT, 5Y3GT.

http://www.kevinchant.com/uploads/7/1/0/8/7108231/ns.pdf

Those Astors can be the very devil to get apart. The brown ring behind the knobs has to be undone and they can get stuck, and break easily. The dial lamps are in a spring that refuses to let the globe get removed without destroying both the globe and the spring. And so on. I detest them.

There's so many models with entirely different insides but use the same case. You could get AC models and also battery types.

Yes I noticed several different "innards" in ones I found pictures of trawling the net. Truthfully I admit I did just go for the lazy man's fix, hoping the resistors would be ok... Your not kidding about those brown bakelite screws behind the knobs, I managed fortunately to get them apart without any destruction, and was wondering what would be a suitable lubricant, I could put on the thread which would keep them easily removeable, I'm afraid to use grease etc in case it reacts with the bakelite... The dial lamps all work well, that's one good thing! Will post valve lineup as soon as I have another go at it, which will be soon. Just had a huge storm here phone lines are down, so will be swamped with RAA work (callouts) once the phones are back up and running! It truly is a lovely looking radio!

Not much will hurt Bakelite though I think silicon spray will be a better bet. When it dries it doesn't leave any residue but when grease dries it just cakes things up.

Thank's Brad, Silicone spray is good stuff, we have in workshop! There's rubber grease but grease does run and cake up over time.

Ok it's got NJ 2733 stamped on the chassis, I can confirm the valves are: 5Y3GT, 6V6GT/G, 6G8G, 6A8G So now I'll check out Kev Chant for a schematic, so I can do the resistors and follow the wiring and make sure everything goes where it should!

Ok I have replaced all of the resistors around the 6V6GT, these were all out of spec, but not too badly, the 50k was about 59, a 60k about 65, so yes, a bit on the high side, I did all of the ones around the volume pot, after that the ones I checked were in spec, I havn't checked every single one around the coils, as yet, but what I have by and large are fine, but still nothing out the speaker but a faint hum, regardless of volume, strangely whilst turning the tuning knob, the radio I was listening to while working on it started making "Cartoon radio noises" (If you know what I mean) at a certain spot when turning the knob. I have known good radio to do this when tuning another good radio in the same room as they arrect each other, so I'm guessing that this suggests the radio is working ok, and that the speaker transformer primary is in fact open circuit. In any case I have ordered another from Canada, check out the following link:

http://www.ebay.com.au/itm//201614272267

The only other thing is the possibility the 6V6 Valve is crook or an RF coil may be oc... Any thoughts welcome.

G'day Jamie,

The reason for the continuity test not beeping on the primary of the output transformer is the high resistance of the winding.
A measure of its resistance is a better test.

If you power up the radio, turn the volume control to about half way, place a small screwdriver blade on the centre lug of the volume
control, (The one which connects to the .05 capacitor), then put a finger on the shaft of the sdriver a good "blurt" from the speaker
gives an indication that the audio section is working but not maybe correctly.

The effect on your listening radio, (Cartoon noise), is an indication that the oscillator section of the 6A8 converter valve is working.

Do you have a copy of schematic? Kevin Chant has one on his web site and I have one I can mail to you if you like.


Cheers, Graham...

Thanks Graham, you understand what I mean by "cartoon" noise lol. Yes I have a schematic, which I have been using to trace the circuit and test and replace resistors, however I am sure I have got all of the bad ones fixed and done all of the caps, so I'm stumped if it's not the speaker transformer? Maybe a valve has failed? Voltages seem right everywhere they are supposed to be...

I'll try that screwdriver trick, next time I get to pull it apart, so long as I don't get a boot from it! I suppose the volume pot is a resistor it'self which my have failed too! Cheers Graham!

Finally got this beauty working, seems some clown forgot to replace a wire connecting pin 6 of the 6A8G to pin 4 of the 6B8G, (sheepish expression) after studying the schematic for hours and scratching my head checking voltages etc. I discovered and corrected my error, with wonderful results! Yay, first one I have not only replaced all of the caps, but half of the resistors too!!!