14-11-2011, 07:54 PM
I was given this set by a nephew as a reward for restoring a Ferranti 045 which I covered in another restoration story. I've mentioned in another thread the fragility of Fenman1 knobs which are made of clear polystyrene and are push on/pull off types secured with a spring clip rather than being secured with a grub screw. However, any attempt to pull the knobs off a Fenman will almost certainly fracture them, with little likelihood of being able to source replacements, so it's far better to remove the chassis complete with tuning dial and to carefully prise the knobs off from behind. That's what I did, but though I managed to remove the knobs intact, they were crumbling away, so I set about repairing them by turning Perspex shafts, which I've referred to elsewhere.
I've just embarked on restoring the chassis and have had a good run at it today. It is AM/FM and the component count is quite high - it has 68 caps and 43 resistors (as compared to a Bush DAC90A, which only has 28 caps and 18 resistors), and seven valves, including an EM80 'magic eye'. Several of the caps that need to be replaced are accessible, but others are lurking deep inside the chassis, with other components above them that need to be temporarily removed to gain access to the ones beneath them. In short, it's a bit of a rats' nest.
So far, I've replaced nine waxy caps (well one was a crumbling brown mouldseal Hunts), and six electrolytics, (two in one can - the smoother/reservoir caps). I often find that smoothers can be reformed on my homebrew cap reformer but in this case, when tested on my ESR meter, one of the sections was open circuit so I had to replace the twin cap, which involved a bit of 'surgery' on the chassis as the original was fitted to the chassis with bent tags rather than the more usual circular clip. There are another four waxies lurking away which I need to swoop on, and one electrolytic. Although its ESR and capacitance is fine, I figure that after almost sixty years, for the sake of a few pence and five minutes work, it might as well be culled.
I have to say that once more, I've found the 'Col coiler' which Colin kindly made for me as a little surprise, to be invaluable. For anyone unfamilar with the device, you simply cut off the old component and leave about 1cm of wire still attached to the tag (valveholder tag etc), coil the end of the new component, slip it over the short wire left on the tag, and solder it in place. Far easier than messing around with a solder sucker trying the remove the last remnants of wire from a tag, risking damage and disturbance to other wires and components. What a nifty and cleverly contrived little gizmo that it!
I've tested most of the resistors, and generally leave them in place if no more than 15 - 20% out, albeit the original tolerance is usually 10%. As expected, some are well over their stated values by 50% or more. One approach is to leave them in place, and often the set will work fine, but I prefer to replace any that are so far out. I usually use 2 Watt metal film ones as they're nearer to the physical appearance of the original 1/2 Watt ones.
The Golborne Swapmeet has come at a handy time to top up my dwindiling polyester cap stocks!
I've attached a few pics of progress to date.
Hope it's of interest.
I've just embarked on restoring the chassis and have had a good run at it today. It is AM/FM and the component count is quite high - it has 68 caps and 43 resistors (as compared to a Bush DAC90A, which only has 28 caps and 18 resistors), and seven valves, including an EM80 'magic eye'. Several of the caps that need to be replaced are accessible, but others are lurking deep inside the chassis, with other components above them that need to be temporarily removed to gain access to the ones beneath them. In short, it's a bit of a rats' nest.
So far, I've replaced nine waxy caps (well one was a crumbling brown mouldseal Hunts), and six electrolytics, (two in one can - the smoother/reservoir caps). I often find that smoothers can be reformed on my homebrew cap reformer but in this case, when tested on my ESR meter, one of the sections was open circuit so I had to replace the twin cap, which involved a bit of 'surgery' on the chassis as the original was fitted to the chassis with bent tags rather than the more usual circular clip. There are another four waxies lurking away which I need to swoop on, and one electrolytic. Although its ESR and capacitance is fine, I figure that after almost sixty years, for the sake of a few pence and five minutes work, it might as well be culled.
I have to say that once more, I've found the 'Col coiler' which Colin kindly made for me as a little surprise, to be invaluable. For anyone unfamilar with the device, you simply cut off the old component and leave about 1cm of wire still attached to the tag (valveholder tag etc), coil the end of the new component, slip it over the short wire left on the tag, and solder it in place. Far easier than messing around with a solder sucker trying the remove the last remnants of wire from a tag, risking damage and disturbance to other wires and components. What a nifty and cleverly contrived little gizmo that it!
I've tested most of the resistors, and generally leave them in place if no more than 15 - 20% out, albeit the original tolerance is usually 10%. As expected, some are well over their stated values by 50% or more. One approach is to leave them in place, and often the set will work fine, but I prefer to replace any that are so far out. I usually use 2 Watt metal film ones as they're nearer to the physical appearance of the original 1/2 Watt ones.
The Golborne Swapmeet has come at a handy time to top up my dwindiling polyester cap stocks!
I've attached a few pics of progress to date.
Hope it's of interest.
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
If it wasn't for the fact that I still managed to do the Times2 Crossword and Codeword every day, I'd think I was starting to lose the plot!
