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Old 27th Nov 2018, 7:41 pm   #1
David G4EBT
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Default A new lease of life for a KB FB10 'Toaster'.

Over the years, at events such as the NVCF, Golborne Swapmeets etc, for nominal sums I’ve bought a number of KB FB10 ‘spares or repair ‘Toaster’ radios with damaged Bakelite cabinets, have restored the electrics and repaired and re-sprayed the cabinets in various colours. At the recent Golborne event, on Mike’s ‘A fiver or less’ pile I found yet another Toaster with a damaged cabinet. Knobs, dial and base were all intact, and at a fiver, it’s not much of a gamble even if it’s a non-worker.

The earlier MW/LW FB10 had a frame aerial – the FB10 MK2 (from Serial Number 110,001) had a ferrite rod aerial and a different valve line-up but they also seem to have variations in the valve line-up with a mixture of B9, Octal and B7G valves. This one has a ferrite rod aerial, so is a MK2, the valve-line up of which is stated as:

V1: 6BE6 (B7G)
V2: 6BJ6 (B7G)
V3: 6AT6 (B7G
V4: 6BW6 (B9A)
V5: 6V4 (B9A)

The line up of the earlier version was:

V1: 6BE6 (B7G)
V2: 6BA6 (B7G)
V3: 6AT6 (B7G)
V4 6V6GT (Octal)
V5 6X5GT (Octal)

The set had no serial number and the line-up was a mixture, in that V1, V2 & V3 were MK2 valves, but V4 was as the earlier version - a 6BW6. V5 initially posed a mystery as it had an octal valve-holder on the chassis, but had a neatly made adaptor consisting of an Octal plug and a B9A holder, plugged into the holder, presumably fashioned by a former ‘custodian’ of the radio. The B9A valve that was plugged into the adaptor had lost its markings so was something of a mystery. I checked the cross-wiring of the adaptor which seemed to indicate that the B9A valve was a 6V4. It worked fine so I left it in place. (I assume that the octal valve would have originally been a 6X5GT).

The adaptor reminded me of one that I’d made some years ago when I couldn’t find a genuine EBL31 valve (double diode-pentode) to fit into my Ekco A22. I made an adaptor to enable an EL84 to be used along with two germanium detector diodes till a genuine EBL31 came along.

All but one of the waxy caps had been replaced, so I replaced that one. Everything looked in order so I tried the set on my lamp limiter and it worked fine. I switched it to be powered direct from the mains, checked the voltages and all were close to spec. The alignment was spot on.

A neat feature of this compact set is that it uses an auto-transformer rather than a dropper, so it keeps the heat down, but of course it means that the chassis may be live, so live chassis precautions needs to be taken. One oddity was that the two parallel resistors from the auto-transformer to the rectifier anodes are stated on the service data as being 150 Ohms each, (hence, 75 Ohms in parallel) but the markings on them clearly show that they’re 330 Ohms each, (165 Ohms in parallel). They actually only measure 65 Ohms. Rather unusual for carbon composition resistors to reduce in valve with age, but it does mean that they’re close to the stated spec, so I left them in place. They appear to be 5 Watt resistors, so share the load to the rectifier anodes, (which are strapped together).

The ferrite rod aerial was lathered in a thick coat of wax to such an extent that anyone could be forgiven for mistaking it for a mains dropper.

I filled the crack on the cabinet with epoxy car body filler, sanded the cabinet with 220G wet and dry, primed it with acid etch primer, and finished it in Wlko ‘Duck-Egg’ blue gloss. Excellent paint at only £4.00 for a 400 mL aerosol can, which comes in a range of colours:

https://www.wilko.com/en-uk/wilko-en...00ml/p/0466173

Sadly, with FB10s, the bright green silk speaker fabric fades over time and looks shabby, so I found a piece which didn’t look out of place as a replacement.

Total expenditure was £9.00 – a fiver for the radio, £4.00 for the paint (lots left in the can).

A little bit of effort, a lot of fun and a nice end result. (The last one I restered was given a red ‘overcoat’).

Pic 1 below is a rear view of the set as found, showing the V5 adaptor in place, and the ferrite rod aerial looking rather like a mains dropper.
The small autotransformer is below the aerial, and to the right, are the two carbon composition (5 Watt?) resistors, R14 & R15 in parallel.

Pic 2 is a close-up of the neatly fashioned octal/B9A adaptor.
Pic 3 is a sketch of the cross-wiring of the plug and socket of the adaptor.
Pic 4 shows R14 & 15, clearly marked as 330 Ohms each.
Pic 5 is of the faded speaker fabric.

I'll attach some pics of the cabinet in another post

Hope that’s of interest.
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Old 27th Nov 2018, 8:02 pm   #2
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Default Re: A new lease of life for a KW FB10 'Toaster'.

A few more pictures of the 'rehabilitated' Toaster.

Pic 1 is the crack that needed to be filled.
Pic 2 is after filling and sanding.
Pic 3 is the cabinet primed.
Pic 4 is the finished radio sprayed Wilko 'duck-egg' blue.

Pic 5 - Hunts waxy paper cap on test:

I mentioned in my earlier post that I'd changed the last remaining paper waxy cap that had been left in the set. I know there are two schools of thought on whether the blanket replacement of waxy caps with no diagnosis is the correct approach, but given that sets such as this one and the DAC90A are now close on 70 years old, and knowing the problems that can be caused if the leak in the electrical sense (audio coupling caps passing DC overdriving the output valve and stressing the output transformer), I share the view it makes sense to change them on sight.

Not everyone is able to check the insulation of caps at their rated voltage and putting a multi-meter across them gives no indication as to how they'll perform at their working voltage. I checked this one out of curiosity on my Victor VC60B insulation tester to see how it held up when subjected to 250 Volts and at its rated voltage of 500V DC. It measured 23 meg Ohms, so quite a high resistance, and unlikely to have caused a problem if left in circuit, but it's had a good life and for the sake of a new cap and a few minutes work, why skimp?

Charming little sets and well thought out. When released in September 1950 they cost £8. 17s. 1d plus purchase tax, so maybe £12.00 in total. When adjust for inflation, that equates to £400 in 2018. How times change - £400 would by a large screen internet enable colour TV. If I'm not mistaken, 1950 was the year that the Queen Mary was converted back from being a troop ship to being an ocean liner, and KB gained a lot of welcome publicity from fitting radios in all the cabins.

Hope that's of interest.
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Old 27th Nov 2018, 8:33 pm   #3
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Default Re: A new lease of life for a KW FB10 'Toaster'.

A very interesting post, and a lovely little set saved! I’ve still not got one of these, but maybe I’ll pick one up at next years NVCF.

I never thought of making an adapter with diodes in the base to fit a more easily available valve. I e got an Ekco U29 that would benefit from such an adapter.

Regards
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Old 27th Nov 2018, 8:44 pm   #4
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Beautiful restoration and as ever, a lovely write-up, David.

Thanks for sharing!
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Old 27th Nov 2018, 8:56 pm   #5
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Excellent work David, well done.

I'm also very impressed with your technique for repairing the cabinet, taking your time to make a well supported and crafted repair really does shine in the end result. These are indeed very attractive little sets and well worth restoring. The cabinets do appear to be prone to damage and its good to see them restored and brought back into use.

Many thanks for sharing with us, gives me some incentive to dig out the one I have lurking in the attic!
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Old 27th Nov 2018, 9:05 pm   #6
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Hi David,
I was similarly puzzled by the parallel droppers.

https://www.vintage-radio.net/forum/...d.php?t=139158

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Old 27th Nov 2018, 10:18 pm   #7
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Hi,

A very good write up with comprehensive information and a well restored set which would possibly have ended up in a skip or been stripped of its valves; excellent job David as usual and I've been privileged to see others you've pulled back from the brink. Your cabinet crack filling works a treat; the crack was a nasty one but who would know now you've worked your magic on it.

Given the age of these sets I too used to change all the waxy caps on sight and many times too the electrolytics curing lots of problems in one go.

The pictures tell the story even better than the text; another set you've saved I wonder what will be next?

Kind regards, Col.
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Old 28th Nov 2018, 8:20 am   #8
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Nice result David.
I have in the past removed the speaker baffle card, and if it is not stained with glue, turn it 180 degrees and the green stripes should then align with the slots in the cabinet.

I have found it common for hard worked vintage low value carbon resistors to drop in value. For that reason it is always a good idea to check any cathode resistors on the OP valve to ensure the bias is still correct.

On my website you can find the 4 different circuits for the FB10, the original 1950, 53, 54 & 55 updates, and also the 1955 FB10/2 service manual.
The 6v4 was used on the FB10 May 1955 circuit and on the FB10/2 and the ferrite aerial was a smaller diameter (5/16") so it would seem that your one is a variation of the FB10.
The fatter ferrite rod, like yours, appears to have been introduced in the July 1953 service amendments.
But to be honest any of these changes can be found mixed and matched as KB changed from one design to another.

This design of radio had quite a long production life and it remains THE MOST common and most popular of all the KB radios.

Another one saved and looking good.

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Old 28th Nov 2018, 9:53 am   #9
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Quote:
Originally Posted by Lloyd 1985 View Post
A very interesting post, and a lovely little set saved! I’ve still not got one of these, but maybe I’ll pick one up at next years NVCF.

I never thought of making an adapter with diodes in the base to fit a more easily available valve. I e got an Ekco U29 that would benefit from such an adapter.

Regards
Lloyd
https://www.vintage-radio.net/forum/...ad.php?t=44574

At the link above, the second pic shows the adaptor I made, which incorporates a couple of OA91 diodes built into an Octal valvebase removed from a duff Octal donor valve and cross wired to a B9A valveholder.

This adaptor enables an EL84 valve to be plugged into the adaptor, and in turn, the adaptor to be plugged into the octal valveholder on the radio chassis without any alterations to the original valveholder wiring, thus enabling the EL84 to be used as a substitute until perhaps an EBL31 comes along.

There was another post here:

https://www.vintage-radio.net/forum/...ad.php?t=44574

It was also covered in an article in Summer 2010 BVWS Bulletin.

As the EBL31 has a top cap and the EL84 doesn’t, it was necessary to provide a “top cap” on the adaptor onto which the top-cap clip could be clipped. I then cross-wired the pins from the octal valve base to the correct pins on the B9A valve-holder, housing the two OA91 diodes inside the adaptor.

The EBL31, being a double diode pentode with a top cap, was a bit more involved than the he FB10 adaptor, (6X5GT - 6V4 rectifier), but I'm sure there are many valves that lend themselves to this treatment, particularly if the original valve is rare or expensive and a more common/cheaper valve is available. An adaptor has the merit of not requiring a re-wire of the valve-holder on the chassis. Where rectifier valves are concerned, there's also the option of making an adaptor by using silicon diodes, and I'm sure I won't have been the first to mention that.
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Old 28th Nov 2018, 9:54 am   #10
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Quote:
Originally Posted by G4_Pete View Post
Hi David,
I was similarly puzzled by the parallel droppers.

https://www.vintage-radio.net/forum/...d.php?t=139158

Pete
Thanks for the link Pete - I'd not spotted it before.
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Old 28th Nov 2018, 10:29 am   #11
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Default Re: A new lease of life for a KW FB10 'Toaster'.

Quote:
Originally Posted by crackle View Post
Nice result David.

Mike
Thanks for your informative post Mike, and for your excellent website.

This 1950 advert shows just what a major player KB was in its heyday:

http://kbmuseum.org.uk/kb_1950_catalogue.htm

I'm always in awe of the designers, engineers and pattern makers and how that blended the technical & functional aspects of radios with the aesthetics to reflect the tastes of the era. It must have been hugely expensive to design and produce Bakelite cabinets, and would need a long production run to get into profit. One of the key selling features of the FB10 will have been that it was compact, transportable, and light enough to take from room to room in an era when radios were too expensive to have several in one household.

I do have an original undamaged set that I bought from a 'junk shop' back in 1980, but all of the others have been damaged in one way or another, so were all under a tenner. I've attached a few pics below:

Pic 1: A wire 'armature' made from a paper clip to help bridge a gap and provide support and strength to the filler.
Pic 2: Gap filled and sanded ready for priming.
Pic 3: Finished set sprayed red.
Pic 4: A pink one (at my daughter in law's request!).
Pic 5: A simple chassis 'cradle' to support the chassis whilst replacing components and carrying out voltage tests.

We're hobbyists and not under the time pressures of radio service engineers of a bygone age. They repaired faults on radios in half an hour and went on their way, whereas we, for the most part, restore them, taking several hours over days or weeks. I've seen examples of people balancing a DAC90A chassis on bits of wood or anything that comes to hand, while they try to replace several components and carry out tests on a live chassis radio on a cluttered workbench. To my mind, that's asking for trouble and makes no sense to me.

Thanks to everyone else for their kind and encouraging comments.
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Old 28th Nov 2018, 11:29 am   #12
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Default Re: A new lease of life for a KB FB10 'Toaster'.

Hi David,

What's your technique for removing the tuning scale spring clip retainers? I've restored three of these sets ..... and struggled every time - usually breaking off the tiny lugs and necessitating a subsequent blob of epoxy resin.
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Old 28th Nov 2018, 11:52 am   #13
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Default Re: A new lease of life for a KB FB10 'Toaster'.

You have to prise them up from the centre, but you are correct they do normally snap off. There is a set of duplicate posts to use when you refit the tuning scale.

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Old 28th Nov 2018, 12:20 pm   #14
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Default Re: A new lease of life for a KB FB10 'Toaster'.

On the subject of dials I know there are many cheaper ways to reproduce dial glasses but I worked with radiodaze and got the following put on their catalogue.
They re drew a dial from a shattered one this is a new graphic file printed on glass (from underneath) it is not a photographed image reproduction.

http://www.radiodaze.com/kolster-bra...-glass-dg-403/

Last edited by G4_Pete; 28th Nov 2018 at 12:22 pm. Reason: added printed from underneath
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Old 28th Nov 2018, 12:52 pm   #15
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Default Re: A new lease of life for a KB FB10 'Toaster'.

Another excellent job plus write up.
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Old 28th Nov 2018, 6:06 pm   #16
David G4EBT
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Default Re: A new lease of life for a KB FB10 'Toaster'.

Quote:
Originally Posted by Tractionist View Post
Hi David,

What's your technique for removing the tuning scale spring clip retainers? I've restored three of these sets ..... and struggled every time - usually breaking off the tiny lugs and necessitating a subsequent blob of epoxy resin.
I made a pair of 'hook tools' which I hook under the clip on either side to prise the clip open and pop it off. The tip of each tool is sharpened and bent to get right to where the clip is digging into the Bakelite peg and the clip is easily levered off with the two tools. The attached rather crude sketch might make it clearer.

I claim no originality for the tool - I've no doubt that others have done something similar. I used 2mm 'piano wire' but you might just get away with coat hanger wire.
The tool needs to be fitted with a handle or it will just spin round in your hand which you try to prise off the clip.

On sets that have previously been got at by the phantom 'Bakelite peg snapper offer', I've secured the dial using a hot melt glue gun.

I did know the name of those clips, but it eludes me.

Hope that helps a bit.
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Old 28th Nov 2018, 6:50 pm   #17
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Default Re: A new lease of life for a KB FB10 'Toaster'.

Spire clips I think. I just mangle the clip bit with small pliers until they are loose, easy to "rebend" the clip afterwards. Your method is somewhat more elegant though! I too must get one of these toasters, an iconic set to go with the A22 and DAC90A on the kitchen display.
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Old 28th Nov 2018, 7:50 pm   #18
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Default Re: A new lease of life for a KB FB10 'Toaster'.

Yes they do fit well in the kitchen. This is my R4 radio in the mornings.
Pete
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Old 28th Nov 2018, 7:53 pm   #19
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Default Re: A new lease of life for a KB FB10 'Toaster'.

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Spire clips I think.
I was on the verge of calling them that but when I googled it, all I could find with that description was these, which are often used on washing machine panels and the like, to accept self tapping screws:

http://www.skyparts.co.uk/product-ca...s/spire-clips/

Someone will know!

Can't really got to Screwfix and say: "Have you got any of those clip thingies in stock that hold the dial in place on a KB FB10 Toaster radio?"

They'd probably wonder why I'd been allowed out without a carer!
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Old 28th Nov 2018, 7:54 pm   #20
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Default Re: A new lease of life for a KB FB10 'Toaster'.

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Originally Posted by G4_Pete View Post
Yes they do fit well in the kitchen. This is my R4 radio in the mornings.
Pete
Just need to remember which toaster to put your bread in!
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