A dusty relic arrives....

Boater Sam said
I've taped the yellow perils and dipped them in underseal before, they look very authentic.

Yellow rubber cable does seem to degrade worse than any other colour.   

Again, another good idea... at least it is similar to the original tar.

I've ordered some black wax from ebay, so will be experimenting. Lets see what happens if I try placing a new capacitor in a small tube and then pour in molten wax around it. Hopefully, I can remove the tube and hey presto, a nice black wax encased capacitor !   

But....I'm being rather negative here, because I have not even tested the set as yet to see if there are any faults, and we all know the Philips black tar capacitors will be perfect and not leaky whatsoever, don't we......

The Radiospares electrolytic is proving rather stubborn in re-forming. The leakage has come down considerably, but very slowly. At first, I had to keep stopping to allow the can to cool. At least leakage is low enough now so the can remains sensibly cool, and it can be left on.

To aid cooling, I popped it in the freezer for a few mins each time.

One to keep an eye on, I think I would have replaced or stuffed it like the reservoir cap.

Well this evening, whilst awaiting the reformation process with said capacitor, I took a look at the rather tired mechanics of the chassis, namely the tuning drive. 

This consists of a "device" that acts as a slow motion drive over one turn of the tuning knob and a faster movement at the end stops. Needless to say, it was filthy and had a horrible movement. I removed the tuning cord and then the "device". I managed to carefully bend back the lugs and remove the shaft and bearings. Any grease had become a black solid mess and was all cleaned away. I used a thick consistency gear-grease and re-assembled the shaft and bearings. The movement was now silky smooth. The rest of the "device" relies upon sprung pressure applied to the outer edges of the large section to provide a damped feel to the faster movement. There are pressure pads under the sprung metal leaves. It is all rather convoluted, but works nicely.

The "device" re-assembled and re-lubricated

Back in situ.

This is the grease I used, it is of a nice high viscosity and great for volume pot shafts and anything that is good to have a nice slow smooth rotation on. It is meant for model cars and suchlike, but very suitable for other things too.

PYE625 said
This is the grease I used, it is of a nice high viscosity and great for volume pot shafts and anything that is good to have a nice slow smooth rotation on. It is meant for model cars and suchlike, but very suitable for other things too.

  

That's a handy product to remember 

Maybe it should be made a 'sticky'....... OK don't all groan at once 

Marc.

marc said 

 That's a handy product to remember 

Maybe it should be made a 'sticky'....... OK don't all groan at once 

Marc.  

 Dear oh dear  

Well I've come to a sticky end because one of the little leaf springs pictured below had a hairline crack and has now snapped in half....

That's a pain but fortunately not a show stopper for the radio working. 

Would a piece of old clock spring work?

nuvistor said
That's a pain but fortunately not a show stopper for the radio working. 

Would a piece of old clock spring work?  

Yeah, a pain lol.

It is the same material, but has cut outs to fit the fixing support.

marc said
Maybe it should be made a 'sticky'

Marc.  

Probably not appropriate to make this whole thread a sticky but I do think your suggestion has merit.

Perhaps someone should start a thread in the workshop section, the thread could be titled some like, "Useful/essential Products ". This new thread could then be made a sticky and members add products they find useful that others might also.

This gear oil would make a good start. I can think of a fair few I'm sure others will too.

marc said

PYE625 said
This is the grease I used, it is of a nice high viscosity and great for volume pot shafts and anything that is good to have a nice slow smooth rotation on. It is meant for model cars and suchlike, but very suitable for other things too.

  

That's a handy product to remember 

Maybe it should be made a 'sticky'....... OK don't all groan at once 

Marc.  

About twenty-odd years ago I used a compound from Farnell which did exactly this job: I used it for the same job on potentiometers, but also on the drag clutch that operates the muting/ATC defeat switches on the tuning control of the Murphy A40C.

Must have it still, but getting to it...

ETA: this is the stuff - https://www.rocol.com/products/kilopoise-high-viscosity-damping-grease

Chris said

Perhaps someone should start a thread in the workshop section, the thread could be titled some like, "Useful/essential Products ". This new thread could then be made a sticky and members add products they find useful that others might also.

I was taught from my first day in the workshop as a young lad was the most important thing in the workshop is the kettle.

nuvistor said

Chris said

Perhaps someone should start a thread in the workshop section, the thread could be titled some like, "Useful/essential Products ". This new thread could then be made a sticky and members add products they find useful that others might also.

I was taught from my first day in the workshop as a young lad was the most important thing in the workshop is the kettle.  

I believe it was once said of BBC transmitter engineers that whilst the sights and sounds of an approaching thunderstorm would get them down the mast PDQ, the click of a kettle being switched on got them down even faster...

nuvistor said

I was taught from my first day in the workshop as a young lad was the most important thing in the workshop is the kettle.

In our workshop I soon learned it was the flipping teaspoon that was the most important thing, well you couldn't loose the kettle as it was tied to the wall with it's lead. 

Marc.

I have made a slight modification to the tuning slow-motion device.....

Remember the sprung piece that broke? Well I made use of a valve spring clip retainer and fitted that to secure the friction drum.

I re-assembled the tuning mechanism but whilst the slow-motion movement was nice and smooth, the non-geared rotation was not, and even though the tuning was faster, it felt rough and a bit crude. Probably due to the reliance on friction of a less than smooth outer drum pressing against card strips, as can be seen above. Not a nice way of doing it.

So, this is where the modification bit comes in. I decided to see if I could alter the assembly to provide continual slow-motion drive over the whole tuning range. It was quite easy, I just bent the metal lug further back to avoid the rod on the tuning shaft, thus enabling continual rotation of the gears. The lug can be seen at the rear of the drum in the picture below.

There was a tapped out screw hole in the chassis and I made use of it by finding a small metal plate with a hole for the lug. It only just fits and stops the outer drum from slipping.

Only Philips could come up with such a complicated and fiddly arrangement.

PYE625 said
I have made a slight modification to the tuning slow-motion device.....

Only Philips could come up with such a complicated and fiddly arrangement.  

Better the modification than it not working, and this is perhaps one of Philips simpler designs, they did produce so interesting drive cord arrangements.

nuvistor said

Better the modification than it not working, and this is perhaps one of Philips simpler designs, they did produce so interesting drive cord arrangements.  

Well it worked, just not very nicely. Even with the now permanent slow-motion drive, the tuning speed feels like a normal radio tuner. Furthermore,  the drive cord goes around the tuning drum on an inner circle and the pointer drive cord is on the outer circumference which results in the pointer movement being geared up a little anyway.  

Haven't done anything else as it has been too hot and I've been too lazy. 

The Radiospares capacitor leakage has come right down now and will be fine. I was worried because it was taking so long, but a few hours on the re-former each evening this week has worked wonders.

On and off today and this evening, I have dismantled, cleaned and re-assembled the tuning pointer mechanism and scale assembly. It is quite complex but very well made. Two scale lamps shine onto a painted piece of glass and this provides a nice back-light to the scale. Wire is used in place of drive-cord and thank goodness it was unbroken. Was rather fiddly getting everything back into place.

I have also cleaned the rest of the chassis and re-fitted the valves. So....does it work?  Well yes, very well indeed pulling in many stations on all bands with ease. After a short time however, the sound starts to become distorted and I suspect capacitor leakage as a possibility. I have not undertaken any measurements today, but will start to have a look around the circuit tomorrow.

Oh, I forgot to fit the magic eye  

The scale is in fantastic condition.

I suspect some of these are leaky.

After testing the chassis yesterday, as I said there was audio distortion that increased after a short time it was switched on. I was assuming this was due to a coupling capacitor to the grid of the output valve. For a quick test to eliminate the audio output stage, I fed a signal into the Gram input. No distortion. So, conditions must be changing further back in the set.

This would make sense as there low voltages around the coupling capacitor to the output stage...it is not coupled from an anode of a previous valve as is usually found in other sets, so the grid is not becoming more and more positive as can happen when this capacitor is leaky.