I was wondering if some one could help work out what this radio record player make is that I am restoring and I am trying to find the circuit, the valve line up with the valves that I can make out is audio transformer is stamper 12th JAN 1959.

5Y3, 6U7G, 6F6G, 6A8G, ?,

The 6A8G I have deduced from other radio diagrams that I can make out from the inside of the glass envelope as it was cracked, there is one other valve with a 6 pin base that looks very much like a 75 valve double diode triode but not sure.

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The chassis looks very much like the one featured in silicon chip Armstrong C5 dual-wave console but might not be.

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That valve line-up, with 6B6G added, was quite popular over many brands/models between 1938 and 1947.

Radiomuseum lists lots of models, but I haven't checked each individual one for radiogram or not.

The only quick references to single band radiograms I can find in my data are:

AWA 310 (1939)
Hotpoint A65MG (1940)
Hotpoint A45MG (1941)

I have had a look, the wild card is the 6 pin valve that looks like a 75 valve most other radio's use 8 pin valves before the amp I have not found many valves that are six pin in the other radio set line ups that use similar valves.

Sets that old are certainly not my specialty but I would expect a chassis with a 75 to have an 80 rectifier and a 42.

Marcc may be able to pick it.

Could the 6A8G be in fact a 6K8G?
There are 3 models of National circuits with that valve line-up including the oddball 75. The models are all D/W including 9/41 (mantle) 9/41 (console) and 9/46S (unknown). The schematics for these are in the AORSM Volume 3. Unfortunately I don't have a copy of that volume.

EDIT. Also look at Eclipse 588, AORSM Vol. 2. Valve line-up: 6K8G, 6D6 or 6U7G, 75 or 6B6G, 42 or 6F6 and 80 or 5Y3G. And Peter Pan 587, AORSM Vol. 2. Valve line-up: 6K8G, 6U7G, 75, 6F6G & 80.

National/Eclipse/Peter Pan are all related.

I have AORSM '37, '38, '39, 40/41. Nominate what is wanted and will scan.

Thanks guys I think we are on the right track now I will have to trace the circuit when I get a chance, I have the AORSM vol 3 not in the best of condition but I might scan and clean it up at some point.

I have found the national 9/46s and 9/41 they seam to be close to the mark including the 3 pos tone switch and the first valve might be a 6K8G as the only visible identifier on the valve was a 6 and a 8g and would explain the 75 valve.

But if someone has the circuit for the Eclipse 588 or Peter Pan 587 I would like to compare thanks.

I'll send the Croyden/Eclipse/Peter Pan 588 schematic to be uploaded here at lunchtime. I think this may be a base circuit for various generic Eclipse made D/W chassis'.

Click on circuit diagram for larger resolution

Thanks Monochrome625 I will get to work on it.

Watch that PSU circuit, those confuse the yanks repeatedly.

It is back biased, but the trap lies in the field / choke being in the B- rail not B+. That means that both filter positives end up on B+ (Big pins on 80) (2 or 8 on 5Y3) and first cap neg. goes to the floating CT the other to chassis. I normally use a minimum of 500V on those rectifiers.

350VAC should give around 330VDC CT to B+ under load possibly a 250V B+ chassis to screen of OP valve.

Do check circuit against what you have.

I did notice the choke on the negative rail, but here is a problem in itself, there is no choke in this set at all some one has replaced the power transformer at some stage,
You can tell as there are for holes that where obviously from a bigger transformer.

I am still trying to work out where the HV side center tap was originally connected on this set it was terminated at the negative end of a 24μF electro and that's all some one has done a bit of a job on the set I know the 5Y3 works with the HV tap to ground I get 280 volts DC and have replaced all the paper and electro caps,

The 6F6G tube needs replacing as it gives a violet glow from the center around the grid and there must be a short as the grid glows orange as well when I get the replacement I should be able to at least test the audio section and work from there.

Are the chokes in the HV supply section like small transformers? This set shows no signs of ever having had one.

This is why I said check the circuit. I will never power an unknown radio until such time as I consider it safe to do so and that may not be until I have replaced several bits in it.

I note that this posted circuit shows no speaker transformer. Should you run it with out one you will, or have cooked the screen grid. If the plate is open it becomes the grid. and if the control grid is open you have a diode.

Circuit shows a choke of 1500 ohms going to the back bias resistors, 200R & 45R. If it has a choke it will look like a speaker transformer, have two wires only and most are topside, not in the pan.

If the choke is actually missing? The 1500R goes from CT to the two back bias resistors, then to ground. The negative of one electrolytic goes to the ct and B+, the other B+ & ground.

The circuit specifies 8mfd shorting CT to ground overloads the set & deprives the valves of proper grid bias... absolute No No. and too much (32mfd) will help kill the rectifier. Do not run the rectifier sideways

This set has the transformer mounted on the speaker itself and the speaker has a field coil not a permanent magnet.

I did come across a another forum where a guy talks about restoring a set much like mine and how they use the field coil as the HV choke that would explain why this set does not have one.

I am taking all this information on board and I thank you all for your help, I am learning working with valves is different from transistors and ICs.

I have already restored 4 radios but this one is challenging me a bit not only because some one has messed up the wiring before I got it, but they used different methods than you would expect but that's half the fun of electronics challenges you.

The speaker is electrodynamic and it's bobbin is the choke. That means three to five wires going to it.

As I said before, this is one of the odd ones. Most fields are in B+: This is not, and that confuses the hell out of a lot of people.

Study it carefully. One wire from the field will be on CT the other on the "Back bias" resistors and they take it to ground (B-): All logical.

Hi how did you go with the Unknown record player /radio? picked up very similar on eBay $5.00. Ticket in cabinet , says AUSTONE receiver No k5477.postal address is Eclipse Radio Ltd, South Melbourne. It's only a Terms of Guarantee ticket. No Valve line up. Embossed in radio chassis is the receiver number K5477.
But the valves are 80, 6F6G, 7? 6 pin (very similar to 75, not sure also),6U7G 6K8.

Speaker is rola K8 / 2.500.