One of the very first things I noticed when removing the valves was pin 3 on 6A8G had a solder “point” on it, so it appears a previous repair was done on it?

Pin 3 – Grid 1 (Mixing grid, connects to signal input), is this correct?

For a quick look at the original circuit LG on this site.
Go to special projects, scroll down to "1940's Little General".
Click on part 1.
In that doc I have the original circuit by John Moyle.
You will see the WW volume control hooked straight to the cathodes and chassis.
I'll bet a lot of little radio makers simply took Radio and Hobbies circuits and used those as a template.

Another tip about moving valves, look at the top cap connection!
Did the wire fracture from the clip but still held by the insulation?

Got to be something simple wrong.

Phenonix,
My suggestion is to fix the problem that is stopping it from working the way it was.
Do not start replacing parts or changing wiring!
Make it work, and then improve it if necessary.
Its a beaut little set and should work like a charm.

Fred.

For a quick look at the original circuit LG on this site.
Go to special projects, scroll down to "1940's Little General".
Click on part 1.
In that doc I have the original circuit by John Moyle.
You will see the WW volume control hooked straight to the cathodes and chassis.
I'll bet a lot of little radio makers simply took Radio and Hobbies circuits and used those as a template.

Another tip about moving valves, look at the top cap connection!
Did the wire fracture from the clip but still held by the insulation?

Got to be something simple wrong.

Phenonix,
My suggestion is to fix the problem that is stopping it from working the way it was.
Do not start replacing parts or changing wiring!
Make it work, and then improve it if necessary.
Its a beaut little set and should work like a charm.

Fred.

Thanks Fred, acknowledging your advice and reading now, very informative

Just did a test on the volume control
Probe on the centre lug that is soldered to the chassis, other probe on right hand side lug that has a wire routing to the cathode.
165 ohms when volume is turned to the lowest position, does not change as I turn it but then at the highest volume position it is showing 13 ohms
Knob turns ok but at the very last point slight crunching sound.
Maybe the volume control is faulty?

Additionally what is the orange thingy inline from the wire that routes to the cathode, there are 2 twisted together (one hidden) looks like RF choke?

Finally previously there was a crackling sound coming from the speaker when turning the knob that no longer happens , now complete silence only the hum if the radio

Volume pot is completely sealed , impossible to open, plus was rather rusted on the bottom part of it

Looking at the photo, the circuit looks quite simple. I'd suggest you draw out a schematic diagram, otherwise we are only guessing.

It appears that the previous restorer hasn't replaced any of the old resistors, which may no longer be working. Since there's so few, you may as well measure them all.

Hi Phenonix, don't get diverted by the volume control, its fine as it is.

I'll repeat, the set once worked with all the parts it has now.
THEN the valves were taken out and put back in.
During that exercise "something" was disturbed.
NOW the set wont work normally, from your description will not "tune in" any normal stations.
From your description, it does receive signals from a low frequency band.
That leads me to assume the convertor is passing signal, but no oscillating is taking pace so no conversion and no tuning of signals.
As I said before I believe the set is working as a straight "TRF" receiver forcing through the narrow band IF tuning coils..
That means 99% of the set is working but something around the convertor stage has changed.
Hence my statement the local oscillator is not running
Without any more detail known I would look carefully around the convertor stage and look for something broken or dislodged by handling.
This could be anything from a bad contact on the valve base/socket or a component lead fallen off.

Without proper testing by using signal injection and logical Measurment that's all you can do.
There is no reason to change any parts, or re-wire anything until the current fault is discovered and rectified.

Cheers, Fred.

That volume control is not sealed. You remove it and on the front will be lugs. Prise them back and the cap will come off. There is a minimum tube self bias point and a maximum. As I suggested there was likely to be a fixed cathode resistor in series to establish the lowest self bias point, which would be destroyed if the pot went to ground.

If you measure the voltage from pin 8 cathode to ground and its hundreds of volts the cathode is open circuit to ground which will the pot, or the resistor at fault, or a bad joint.

When removing top caps (signal grid on 6A8) it is quite easy to break the top cap from the tube. That can often be fixed, don't throw away the tube.

Where there is rubber insulated fly lead exiting from a can like EBF2; Old rubber wire often becomes brittle and it can crack, then short where it comes through the hole: I have had more than one with that issue lately and at the tube end it can short to shields (where fitted). That scenario can manifest when the tube is removed. That can often be fixed easily if the cover only can be removed.

ARTS&P label says it could be a commercially manufactured set and its colour & numbers might who and when.

Hi guys I have the set on my work bench now and it is going to be an interesting exercise to sort out.
The fact is the set did work in as much as receiving stations but after physical handling, failed to.

We suspected the audio side worked but the IF and convertor sections did not.
I guessed the local oscillator was not running in my posts and was correct.
The good news was that was an easy fix, the by pass on the plus feed to the plate supply was not connected giving low supply voltage.
The bad news is with that fixed and oscillator running there is still no conversion or IF signal!

I did inject SG IF signal into the 6A8G and EBF2G (octal base) circuits and found the IF transformers resonate at around 390Kc.
The trimmers on all four coils peak roughly on centre so the coils are active.
The coils do not resonate at any other frequency from 100KC to 2000Kc. IE not 175Kc or 1800kHz
I have a gut feeling that the gang tuning coil set has damage or non-matching parts.

At this point I was working with no circuit just poking around and guessing.
Time to stop guessing and draw the circuit out before I do anything else.

Question. Has anybody struck a set with IF's tuned at that odd frequency?
Possibly to suit some other oscillator coil?

Fred.
I

Believe Rodney Champness wrote something on IF frequencies. With the tubes in that set I would expect 455kHz or around 460kHz. The major odd ball was HMV at 457.5kHz ensuring Heterodynes landed off the stations.

One Stromberg Carlson was 392kHz See the Arthur Cushen's list (HRSA) and twice 175 is 350.

As I mentioned using 6J8 instead of 6A8 can compress the band spread and land it in amongst the NDB's. So has a problem developed that would change a coil resonance: Like water / CRC in a trimmer or a broken wafer? That also applies to some one messing with the coil factory Mica caps on them, or has one broken free cleaning.

Chasses like the big Midwest ones were apt to squirm & things badly soldered broke free. That also applies to IF's, as I have had some where internal caps have broken free, or off. (see Radio Waves recently).

You may have to determine what frequency the oscillator is actually running at? A loss of a capacitor generally sees the osc frequency go high & a higher capacity go low .

Do check the grid resistors on 6V6 rarely are they in spec.

It was a pleasure to meet Fred personally yesterday having dropped off the radio to him, being a complete novice myself on these matters it was a buzz for me to watch him in action.
I just want to say here thank you Fred for giving your time on this.

Hi Marc, thanks for the thoughts about IF.

Of course, the IF frequency can be whatever you like, if ignoring a lot of technical reasons.
When you look at the collection of horrors trying to be resistors and capacitors in this chassis it's a wonder anything works.
I'll trace the circuit and then have a closer look at the tuning and oscillator running frequencies and see if this matches up with the IF setting.
All the coils look like misfits from various sources, not a matched set like you would see from Kingsley or RCS.

The ARTSP label is stuck on an IF can, but that can may have come from some other set!!
I have not seen IF coils quite like these, i'll get a can off one and see what the coils look like inside.
The size and measured inductance of the coils will give us a clue as to what frequency they should be.

More later.

Fred.

392kHz puts it in the NDB Band so that may explain that and the issue is in the antenna section?

So, I agree on trace out the circuit, I have over time found that tedious but necessary, to the point I have an AutoCad just for that, on a computer that just wiped out the PSU module and need a new one.

Watch 6A8; it and it derivatives are even bagged by RCA, its never unusual for one of them to short. If there is no spare? 6J8 will provide a conclusion to the 6A8 being faulty.

I too have a feeling its a bitsa, & it will be interesting to see if tracks properly. It seems to have a lot of wire wound resistors and they tend to cause havoc if in the RF section.

I got the set going and did an article about it.

I'll close this thread off and present the article and put follow up comment in the Special Projects section.


Fred.