#42 to 6F6 is only a socket change. The only difference is the base; it is the same valve envelope & content. As said I reverse engineered the other one. You may have to do same. Its not that difficult.

Several numbered tubes like 2A7, 57, 58, went for a long time with base, heater and number changes only. So it is feasible to have all the valves, heater voltages and sockets changed without any need to alter the rest of the circuit.

Marc

You might even find that the octal socket was added later by someone who couldn't obtain a 42.

Well guys my next little idea for this one is to see if I can get one of my young friends to 3D print the old caps in this baby and also photo shop the labels for me so I can make some hollow blanks and cleanly stuff the new caps into the blanks. Then I may see what the viability of making numbers of blanks incase any other collectors want to do this. I am also thinking of lifting or masking off the components on top of the chassis so I can freshen up the top with a coat of paint. I am really thinking of going the extra mile with this one.

Ok I know this may sound like a stupid question but can I move the tag board underneath the transformer or is it likely to be solidly attached. The reason why I ask is because it fouls the pot in front of it.

Would an alternative to removing the tag board be to put spacers between the transformer and chassis to to raise the transformer and hence lower the tag board as seen under the chassis? Presupposing there is enough clearance between the tag board and the underneath of the chassis.

The aerial wire runs past the transformer terminals to its hole in the chassis. Perhaps this wire should have spaghetti tube over it.

Despite the fact that the image pixelates to virtually unreadable. It looks like the offending piece is marked "E" If so that is the internal shield & can be proven by the fact that if it is un-wired it will have no commonality with any other winding. It is also a reason for a grounded cable.

That transformer looks more like a Henderson than an EMMCO. You will not remove that plate. I would consider carefully knocking off the corner, whilst being careful not to damage the pot. You can always wire to the inside part of the terminal and use the good Araldite (not 5min) to secure the terminal or remove it & splice to the HT common as it looks like its grounded & not back biased.

Marc

Marcc by any chance would you remember what the value of the pots were on the EMMCO you worked on .

Hi Carl

If the volume pot is in the cathode of the IF amp with 100 ohm in series it'll be 5 or 10k. You may be able to find a smaller diameter one to clear the power transformer lug. But there is enough current there to mandate a wirewound pot.

It was common practice to ground the slider and connect the other end of the pot to the antenna. That way, if your signal was really hot, you could shunt it to ground at minimum volume. No AGC in those days of course.

If the original Tone pot is in the 6F6 plate circuit it'll probably also be 5K.

Regards the paper caps, after taking pics and cutting them out, here's what I do:

1. Hang them by a pigtail in an oven at 200 degrees with a pan underneath.
2. Either the paper shell will drop off or you can remove it easily while it's hot with kitchen tongs.
3. Put the new cap inside the old sleeve. You may need to solder some longer wires onto them.
4. Seal the ends with hot-melt glue.

Easy-peasy and looks completely authentic.

For the power connector, try this link:

http://au.element14.com/webapp/wcs/stores/servlet/Search?pageSize=25&st=Neutrik+PowerCon&catalogId=15001...

These professional connectors are ultra-safe and very rugged. Avoid the bright colours though!

Regards refinishing the chassis, I have done this to three Airzone Radiostars:

1. Drill out the valve socket rivets
2. Disconnect the IFT, mains transformer etc. wires (after taking pics of course)
3. Withdraw the entire wiring loom from the chassis
4. Remove other parts from the chassis
5. Sandblast the bare metal, or use a wire brush, whatever's appropriate.
6. Paint or electroplate (I use zinc) the bare chassis to match original.
7. Reassemble using pop rivets for the valve sockets.

Ok my next question is about the wire wound resistor between the dial lamp and ground ( I think ) its wire on a flat biscuit about 10mm by about 50mm. it seems that I may have to either rewind it or hide a new resistor behind it. What would its value be please ? Or what wire can I rewind it with . The resistor is actually in parallel with one of the power wires to the Lamp.

I will look at pots, don't have to remember, circuit was in Silicon Chip & I am sure I sent Kevin Chant a copy; I will have what I drew: Will look

Marc

Volume is in the cathode circuit and antenna coil primary 200 Ohm series cathode side, wiper grounded. I have it marked as 10K WW 3W.

Tone on plate 250K in series with 104 (0.1mfd)

Transformer 380-0-380 That to me spells 600V filter caps.

IF's are bottom trimmers.

Marc

Thanks for that Marcc I only ever use 600 volt electros , the info on the pots is invaluable thank you very much.

I also decided to use a cable gland on this one and am most impressed with the way it holds the cable. I managed to apply power to the transformer with all the valves pulled out. I can honestly say there is no short circuits and no indication of excess heat. So I will perform a full recap and replace all resistors on the valve sockets.

I have been using glands for years as knots are a No No. You can put the pointy end inside in many cases and it also stops the cable twisting off.

On many Consoles, in particular, the wire can go out the side of the chassis. I will only replace resistors 10% out, or worse, & that's irrespective of where they are.

Marcc or any of the other guys can you help me with the values of two of the resistors in the photo please. There is one below the technico capacitor with a orange dot on it , it looks to be burnt out , I think its brown ,brown orange. and there is a wire wound one connected to the pot near the transformer it looks like brown , brown, black to me . I have no issues with the others as they are easy to work out. I am going to replace all of these as they are all high value and are all at least 82 years old .