Restoration started Spot on Time.

[Boater Sam]

Wanted one for a long time, the only radio made by a vacuum cleaner manufacturer? The S.25 Goblin Time Spot Made by the British Vacuum Cleaner and Engineering Company Ltd. 1946 production?

Bought a fair condition one recently for a good price. Obvious faults are a small veneer chip on top back corner, a scratch on one end, only 2 correct knobs and its a bit mucky.

On examination the tone control, no knob, has a shaft that is too short! Oddly it looks to be original but there is no way the correct knob will fasten on.
The chassis is unmolested apart from a new double capacitor can, dated December 1957, a U50 instead of 5Z4G rectifier, EBC33 instead of 6Q7G, 6V6GT instead of 6V6G.
One dial lamp missing. Wavechange and on/off switches a bit stiff. Tuning cord drive is by a bit of green garden twine, incorrectly fitted and useless. The slow motion drive doesn't work in slow, its gummed up with grease as is the pointer drive shaft for some daft reason.
Mains cable cut off, shame because it was a nice black fabric one with a white tracer.
The blue sticky tape over the IF transformer adjusting holes has been pierced so the twiddler may have been here.


Now the good points, the hand set knob on the back is present, the mains and output transformers check out with an ohm meter as do the loudspeaker energising and hum bucking coils. The loudspeaker cone though full of dust and fluff moves freely and quietly. Both back panels are good, one corner a bit soft, pva will sort that.
All valves have heaters and are holding a vacuum ( should do seeing who made it! )
No rust! The clock runs, I can hear it, and the fingers move. It will need stripping and cleaning.

Unsolder the loudspeaker. Remove all valves and brush and blow the loudspeaker and chassis, generally clean it all up.
Fitted a new fabric mains cable with a zip tie strain relief rather than a knot, run it up briefly on the lamp limiter, no dramas, HT comes up, all valves lit. Smoothing can staying cold. Speaker crackles when changing wave band, enough power for now.

Grease the switch ball bearings, change the tone control for a reclaimed one with a longer spindle. Clean all the old grease off the mechanical bits, oil the slow motion drive and it works fine.
There are 3 Sprague capacitors in plastic sleeves that are sweating an oily substance, the AVC capacitor, audio coupling capacitor and mixer cathode decoupler. All out of spec, gone high which means that they are leaky. The other 3 Spragues are naked, dry and test OK, very odd as these capacitors are usually fine. I suspect its the plastic sleeves oozing plasticiser and not the capacitors leaking oil. Another thread on here about these capacitors.
Restuff the 3 sticky ones and refit. The sleeves will have to go back on for originality.
Check all possible resistors without disconnecting them all, the valve bases are the nasty paxolin ones that have solder tags that break off easily, all are within tolerance.

Replace the 2 wrong colour HT wires on the new smoothing can that the last repairer fitted, badly and tidy the soldering. I'll restring the tuning drive tomorrow.

More later.

Sam.

[Tractionist]

Busy Boy! Keep us informed eh? Looking forward to hearing how it performs.

[kalee20]

I'll watch with interest, as I have one too! Bought but not started or powered-up.

Mine may need the motor rewinding, though.

[vidjoman]

Don’t forget that the grille cloth is actually woven brown paper.

[Boater Sam]

Short day today.

Output valve (6V6G) cathode capacitor, 10uf, thinks it is a resistor. Now this is an Ilford cardboard cased job about 3" long, 3/4" in diameter with a CE number! No, its CE for something else.
Opened one end, warmed it up and pulled the innards out. Drilled both end rivets, new capacitor inserted, about 10mm by 4mm, how things have shrunk.
Thread wires through holes, solder to existing leads and refit.

The tuning mechanism is very simple but restringing is complicated by having to remove the pointer, held with a screw and shakeproof washer on the end of the spindle, and scale, two more screws into hank bushes.
Then the mounting panel held by two 4BA nuts and bolts, tricky to get at, I'll glue the bolts into the frame before refitting.

Remove the green string, it wasn't wrapped round the spindle, just under it. Replace with my usual red bead cord. Now it works well and is very controllable.

A bit more cleaning now that there is access to behind the tuning scale.
I think tomorrow I'll remove the clock and see what that needs.

Very soon it will be power up time - at last.

Sam.

[Phil G4SPZ]

Nice to see you're still busy with radios, Sam! I've replied to your PM regarding the clock, and I'll keep an eye on this thread to see how it progresses.

[Boater Sam]

Today's challenge, the clock.

Not renowned for my expertise with clocks, previous attempts with spring driven ones are best not talked about.
But an electric one should be simpler.
The hands, 4 of them, all just pull off, thankfully, and the dial is just 2 screws. Interesting to note that the mounting plate is the same as the one for the tuning dial with the exception of a bracket welded on the opposite way round.
Again getting to the screws and nuts holding it onto the chassis are a bit of a fiddle to get at.
3 wires to disconnect and the extension for the hand set which unscrews, left hand thread, and its off.
3 screws hold the movement to the frame, the alarm set gear just pulls off the spindle assembly.
One screw holding the can and the movement is exposed.

There is thick brown grease on the motor pinion and the first 2 gear trains, and the contarotation cam is also greased to death. Probably original, it appears never to have been opened before.
I've cleaned almost all of it of and lubricated with fine oil as in the other thread and it works well.
Reassemble the clock with its dial and fingers, put it to one side because its now time before tea to give the chassis some power, exciting stuff.

Tack the loudspeaker leads back on, fit the valves and a dial bulb so I know when its on. Dummy wavechange knob fitted, make sure that the mains switch is in the permanent on position, not clock, and power up on the lamp limiter, which is fed from the isolation transformer.

We have reception! Even on the lamp. Give it the beans and we have good reception on all wavebands.
Check that the IF transformers are about right, they are, good, the twiddler hasn't mucked it up.
Sensible set this, all the aerial and oscillator coils are by Wearite, trimmed with trimmer capacitors and the IF transformers similarly are capacitor tuned. There are no coil cores at all to worry about.

Let it run for a while, nothing getting distressed. The tuning doesn't drift either. Radio Stoke and Gold received at good volume, not a lot wrong with this chassis, it will get a final alignment later.

And that closes a satisfying day, time for dinner.

Getting ever closer to having to tackle the cabinet and that delicate speaker fret, its like a Lloyd loom chair, made from paper. I wonder what colour it should be?

The indicator numbers on the volume control are needing replacing, will try to print a new wrap on paper and laminate it.

Sam

[Boater Sam]

Today I printed a new wrap for the volume control. Got the type face right, the spacing of the numbers is very slightly too close but the next font size up was way too wide so it will suffice, it runs from 0 to 12.

Reassembled the clock onto the chassis, replaced the tuning dial frame and scale. Set the pointer and touched up the red paint. 2 new dial lamps to brighten the day.

Stations tune in close to the correct frequency, er, wavelength on the dial, final alignment will get it better.

There is a problem, 2 actually.
The clock sometimes starts in reverse. I do not understand what I can do to avoid this, the contrarotator mechanism is weird and I cannot think what I can do to correct it. It consists of a brass wheel with hooked teeth running inside a hole in a paxolin lever which has or had a tooth in it. I thought it was OK apart for the grease but on reflection I am not sure.

Secondly, the radios runs as designed, for 2 hours after the clock turns it on, but as it turns off after 2 hours, it trips the workshop rcd.
I cannot understand why. The switch in the clock is a simple single pole micro switch, the neutral is not connected to the switch and its insulation to ground is fine. Once it has turned the radio off, the rcd will reset without a hitch.

The radio works well, HT is 40V low, the U50 rectifier is probably not at its best and I can't find the 5Z4G that my stock list says is somewhere.

Made a start on the cabinet whilst I pondered the rcd behaviour.
Cut and fitted a piece of veneer to patch the chipped top back corner. The existing veneer is thick, its curved over the top, so I had to back the piece up with 2 layers of paper to get the surface level. I will trim and touch in this repair in a couple of days when it has set fully.
I am avoiding stripping and refinishing the whole cabinet, the scratch on the side needed filling with wax, hopefully it will blend in acceptably. I suppose a 70+ year old radio should have the od blemish to be authentic.

The celluloid windows are good, not yellowed, and will polish up well I hope. I will try to avoid removing them as they are held by a fragile metal ring with just 2 screws at the top, if they got twisted I don't think they would straighten properly.

The delaminating damaged corners of the lower back panel have set solid after being soaked in pva and left clamped in a vice between 2 sheets of polythene for 2 days.

So, nearing the end with just 2 niggles to attend to and check on the alignment, With no coil cores, just 13 ceramic trimmers to adjust, it should be a pleasant job.

Sam,

[Phil G4SPZ]

The anti reverse rotation mechanism should have some sort of cam which stops the motor and 'bounces' it back into the correct direction. It's possible this has broken away.

Regarding the RCD tripping, is the chassis earthed? I wonder if the microswitch is internally arcing down to earth briefly as its contacts open. You could try an R-C snubber network across its contacts, or replacing the microswitch itself.

Otherwise it sounds like you have a nice set there!

[Boater Sam]

There is nothing broken in the mechanism but I suspect that the single tooth in the paxolin may be worn. It is beyond me to disassemble this mechanism, it would involve totally dismantling the clock and how to recreate a paxolin part would be another matter.
Perhaps I should redose it with thick grease!

I'm going to try a snubber across the micro switch, it will have to go inside the clock else it will show. But it takes 2 hours to test every time!

Sam.

[Boater Sam]

The clock not always starting in the right direction I will have to live with unfortunately. I'm ashamed to admit it has beaten me.

The rcd trip problem is resolved, I fitted a snubber of a period resistor and an X2 capacitor across the microswitch. There is not sufficient room inside the clock can to hide these extra parts, so I hid the capacitor behind the mains switch and used an old dog bone resistor under the switch so at least it looks in period.
Tried it this afternoon and it doesn't trip.
Cleaned down the cabinet and touched in the veneer patch.
Replaced the chassis and loudspeaker in the cabinet and fixed the back panels.
I have had a kind offer of 2 knobs from another member, 12jslater, they are in the post, thank you, so then it will be finished.
I'll get the camera out next time.

Sam.

[Phil G4SPZ]

I'm pleased that the snubber idea fixed the tripping problem. Don't be ashamed about the clock, either leave it plugged in, or just be aware of its behaviour and check every time you plug it in that it's going clockwise.

None of my electric clocks are self-starting, but it's been months since I had to restart one. The mains is pretty reliable here. Anyway, most clock motor rotors have a spring-coupled flywheel which enables the rotor to keep turning through a short power interruption (a few cycles) and re-synchronise quickly afterwards.

[Boater Sam]

Thanks Phil.
Its just annoying knowing what is wrong but realising that the chance of a successful repair is unlikely.
Is 72 years a reasonable period for a clock to work? Is the guarantee expired do you think?

I think it was the inductance of the mains transformer collapsing on power down that upset the rcd, they are fickle things. Perhaps the mechanical action of the micro switch is a little slow, it was never designed to work through an rcd after all. Insulation to earth is good, I checked.

Sam.

[Phil G4SPZ]

I agree it could have been that. The RCD might have seen the back EMF as an imbalance between the currents in the line and neutral. Strange that it presumably didn't trip when switching the radio off normally. One to file away for future reference!

[Boater Sam]

Had an offer of some knobs from member 12jslater, I consider that to be lucky, very grateful. Thank you.
Once they arrive I may have another go at the clock and see if I can induce the ratchet to work every time.
Hate being beaten.

[Phil G4SPZ]

Originally Posted by Boater Sam

I may have another go at the clock and see if I can induce the ratchet to work every time. Hate being beaten...

Next time you're chugging past Dudley on your boat, just bring it into Gripton's one Tuesday and our veteran wireless engineer and self-taught amateur clockmaker will happily take a look at it for you!

[Boater Sam]

Now that's an offer not to be sniffed at.
I assume the modest multiskilled engineer you be a certain volunteering Bewdley resident?
Thanks Phil. It will be a while and just the clock, no room on the boat for the whole radio.

Sam.

[Phil G4SPZ]

You might think that, Sam; I couldn't possibly comment! As you know, you're always welcome. I'll make sure I have a couple of complimentary tickets to hand.