Peculiarities of the KB FB10 'Toaster'.

[Paul Stenning]

Originally Posted by Richard_Newman

You will probably have to obtain several circuits from different sources and kind members of this forum to provide more info (I only have the trader sheet).

I also have the one from Radio and Television Servicing, but that looks like the same circuit as Trader (certainly it's the same valve lineup).

[Chris_C]

I have 2 R&TVS circuits for the FB10 1 is the same as the trader sheet with 6V6 o/p.
The 2nd is the FB10/2 with 6BW6 o/p and several component differences.

It's attached as a zipped pdf and it's quite large. I had to do this to get any decent quality.
Hope it helps

Cheers

[af024]

Thanks very much - I'll have a good look at that info (you just pipped me at the post).

Here's what I was going to say ..

Update

I looked really carefully at my set and yes, I was looking at the wrong resistor. R2 is hiding right behind R1 and is covered in black gunge (no doubt from an old waxy cap and several accumulated years of dust). My R2 is indeed as per the circuit – ie 220 ohm and R1 is 22k as per the circuit. So at least that’s one mystery solved (thanks goodness). So thanks for your info Paul.

I guess I’m not too worried about the R13 issue (although it would be nice to know what it should have been in this particular set), but the C2 and the Hunts 0.001uF capacitor issue is a mystery. I have sketched out the circuit (and judging from the pictures that have been kindly supplied) I suspect that this is what others have got also (although you probably didn’t know it).

The 70pF capacitor is connected to the first two tags on the switch (going clockwise from underneath starting at the 1 o’clock position). Pin number 1 is denoted S1 in my drawing, pin number 2 is the S1, S2 ‘pole’ and pin number 3 is S2.

It can be seen that in this configuration, a 70pF capacitor sits in parallel across L3 (when in LW) whereas in the Trader 969 sheet it does not. L3 is still shorted out when in MW however. When in LW, the 0.001uF capacitor (not mentioned in 969) is in circuit. Hopefully this configuration was one that KB actually used and not just the remains of someone’s botch or my bad eyesight.


Andy

[af024]

Sorry Chris but that doesn't seem to be the beast either. Thanks for your efforts all the same. I'll keep the data safe however (for when I brave another).

Regards,


Andy

[af024]

At last, the beast squeaks again! It's actually quite good. Thanks to everyone for their photos etc. I still can't understand the difference at the front end, but there you go. I've attached a photo of the chassis underside following my toils (using disguised of modern caps).

Those stupid wire wound cap trimmers located on the main vane variable cap drove me mad but I got there in the end. All stations are in their correct places and it's nicely sensitive. I'm really quite pleased. Interestingly the markings on the dial plastic don't seem to agree with the Trader sheet AND they don't look like those shown on other people's photos but at least it was sort of logical when I thought about it.

I have one final query if I may, can anyone please tell me what the band change slider is supposed to look like as regards the lettering? Mine has some remnants of white paint in between the letters (not on top). I can't believe that the entire slider was covered with white paint with only the lettering poking through in black. Surely it was the reverse wasn't it?

Thanks again.

Regards,



Andy

[Darren-UK]

Hi Andy,

On mine the wavechanger is brown bakelite with raised, moulded lettering. No sign of any paint having been on the lettering, but whether the lettering was highlighted with paint originally I just don't know. The words 'medium' and 'long' are in full.

[Ed_Dinning]

Hi Andy, one one of the many varients that I've has it was a speaker mute switch for when the output was fed to an external amp via sockets on the back. I don't think it's on all varients though

HTH

Ed

[af024]

Thanks for the info Darren. I think I'll pick out the remants of paint (which could be someone's previous botched attempt to change the look). Interestingly my control slider is in black whereas yours is brown. Mmmmm. Yet more differences.

Thanks too Ed for your info - I must confess I never knew that one.

As regards the caps, yes I did them myself. Actually when I started this particular set I didn't think that I would go the whole hog like this, but having found some caps that I'd done for other things previously, I thought I'd go for it.

Some time back I looked very closely at the TCC caps that were in a TV22 and a DAC90A and I carefully did some artwork on the computer to mimic the exact font, size, positioning and actual words. I measured up the original cap and made label strips that were the correct size (including the line down one side of course). I print them on creamish/brownish paper, wrap them round the modern cap (using Pritt Stick to fix it) until the diameter is correct (doesn't matter if the ends overhang the cap inside), then dunk it in wax (boiling up on the stove). Actually I found that the temperature of the wax is pretty critical. I seem to get good results if I put the pot of wax into a salt-saturated pot of water - just the ticket. 3-4 dips (alternating the vertical direction) does the job nicely. I use orangey-coloured wax (from the Pound shop) - smells a bit though 'cause it's scented!!

Thanks for your thanks though. It does take time and effort, but I think it's worth it.

Thanks again everyone. Just got to sort the case out now (it's got a crack in the rear and a chunk missing near the tuning knob). Not sure quite what to do with it just at the moment but no doubt I'll sort something out.

Regards,


Andy