Well after recapping etc I turned it on (firstly with test lamp in series ). I was greeted to a deafening silence I found the little dial light globe that I had spoken about was open circuit,ok I was going to remove it down the track anyway so I got rid of it. Powered it up again and more deafening silence. Speaker output transformer o/c also. I have removed the speaker and will hunt around for another transformer , so I have the cone to repair and the output transformer to replace they will be jobs for another day.
Still no comments on silastic there must be a logical reason you are opposed to it it is flexible and can be applied thinner than coffee filter paper. Do you all use this paper or is there a thinner more flexible alternative I just don't like it, however I trust your comments and judgement . On the upside I received Carl's very nice power leads today so I can replace the old lead it will look so much better even if the radio chooses to remain silent.
Regards Jimb.

I try and use tissue paper with the PVA.
The type used with dope, ie aero modelling. Hard to find these days.
As far as the O/C speaker transformer goes, I always carefully pull apart the winding covering and inspect with a magnifier.
Quite often a repair is possible. Broken at the termination or very close to it.
JJ

Thanks JJ I will have a look when I remove it from the speaker.

A141 is in AORSM's the only globe in it is for the dial. If you use 6V6 wire as for the others as 141A is the only one to use 6AG6.

Watch the grid leak & first Cap of the filter they go to CT as the choke is the back bias resistance, with 6V6 OP Transformer is 5K primary.

It has a shielded transformer: Ground the chassis. That fancy new suicide cable will be three wire (one hopes).

Marc

Hi Marc, the "gorilla snot" is in a plain 5L plastic bottle, I guess it was a bulk item at the speaker factory in Taiwan.
Takes overnight to cure going from a cream colour, consistancy of custard, to a smooth slightly sticky clear coat.
Will accept anther coat on top.
Penetrates into the base material and you cannot peel off.
It sticks like , well, um, Gorilla Snot!
Twenty year stable and very flexible.
A blob of it will stretch many times size when pulled apart, before snapping.
I restore rotted cone surrounds by painting on two coats.
I glue in tissue pieces to fill holes in cones and paint the whole cone with a layer.
You wind up with a shiny speaker and takes mist flat black spray can over the top to hide repairs.

Jim, Silastic was a NO NO for speaker repairs, cures hard after a time, peels off under vibration.
Great for outside rusted gutters and pipes!

I used to repair car and guitar speakers, (100's watts) the main adhesive was 2 pack epoxy where the joint could be rock hard like voice coil to cone.
Snot was used on the flexible bits like the suspension. Windings were epoxied.

Re the circuit, I have only the "model 141" where they show a 6V6 with grounded cathode and the centre tap giving bias to the grid resisitor. In practice it does not matter how the bias is derived as long as it is there. There is a difference between laboratory conditions and the real world! The factory may have changed the design around to suit whatever valves and bits they had in stock. Hence the 141A.

The dial lamp is run off the heater supply. Lots of radios put dial lamps in series to run at red colour with 3 volt to reduce the glare and make them last forever. Sticking the bulb in the choke circuit probably did the same thing. I would not have a bulb there in a million years! Bulb goes open and the set stops, stupid!

Fred.

A tip I read about in the HRSA magazine for the use of neutral cure silicone for repairing speakers is to thin it with acetone (but steer clear of nail polish remover which is acetone but may have oil in it) and paint it on. It works quite well but takes quite a bit of stirring to get the silicone to dissolve. Then you need to be pretty smart painting it on as the acetone evaporates pretty quickly.
The main point of thinning the silicone is to reduce the thickness of the repair to maintain the flexibility and lightness of the cone so it can react quickly to the force of the voice coil and produce a good sound.
Neutral cure silicone must be used because conserving a speaker cone is like conserving an old book and acid attacks the paper.
This works especially well for the threadbare areas of the suspension corrugations at the edge. It can also be used to glue on pieces of paper to patch larger holes that can't be bridged with silicon. The suspension gets the most flexing and I have avoided patching with paper here and have used muslin type fabric painted with the silicon.
It is surprising how well speakers can work with quite big holes as long as the voice coil isn't rubbing on the magnet or there isn't rubbish in this space. So the repairs don't seem to need to be super strong. After all the wattage is low so they are not pumping air like a doof-doof car.

Hi all thank you again for your informative comments.
I have no idea where you can by the gorilla snot glue from. A while ago I did buy some glue which was supposed to be for speaker repairs however it is white and looks exactly like PVA glue.
Kind regards Jimb.

If you can get the maker & an MSDS, depending on the level of data other than what they are forced to quote, it may give an idea of what is in it.

Acetone (Ketone group) will also attack plastics & Araldite and Metho: Acrylic, and Nitro cellulose finish. You can use it to identify enamel paint & Acrylic as it does not attack the enamel.

Back bias: You will note that where back bias is used to to set a reference bias, this sees the centre tap floating above the chassis & why you often see the first and sometimes second filter cap, insulated from the ground / chassis. Sometimes that back bias resistance is tapped or more than one resistor.

Normally all cathode current passes through it and the bias voltage is developed by that current. That is why the grid leak of 6V6 goes to the Centre tap. The 12.6 V or so grid bias is developed there eliminating the cathode resistors. The other tube only uses -6V hence the cathode resistor.

This may be related to a Wartime valve shortage or someone getting a "good deal" on surplus. Plenty of that went on; Grey of Fergusson TE-20 series is ex Royal Navy. The stray globe may be someone's idea of a barretter? I have used them for that.

Marc

Thank you all once again. Well ! All's well that ends well so they say . It is now up and running and working very well.
I will down the track give it back to the guy.I left him with the case to clean up.I don't trust myself with things that can be dropped and broken. I have a half built AM modulator surplus to my requirements I will complete this first then I will give it all back to him.I may include one of those little Bluetooth devices I bought another 4,waiting,on there delivery. Very happy with the one I initially received a great addition to use in conjunction with the AM modulator..
Kind regards Jimb.