Ferranti U1003

[kentplums]

Hello

first post for a novice ...

Just got this FERRANTI U1003 off my mum - complete with installation/handbook. When warmed up it makes a loud humming noise and the only channel to be found is 5 live on AM. A friend suggested replacing the 'big capacitor by the transformer' . The most obvious one is light blue, 45µf 300v (I think) tucked up in the Bakelite case. looking at the soldering it has been replaced before. Is this a good place to start?

Any help or input gratefully received.

Thanks,
R

[Ed_Dinning]

Hi, Please do not run the set anymore until you have read the servicing advice at the start of the forum, where it will tell you to replace THAT capacitor (not the big one) first.

If this is not done and this cap may cause damage to valves and transformers and make what was a simple job a prolonged and expensive one.

Plenty of advice available when you have read up on the basics, just ask.

Ed

[kentplums]

Thanks for that Ed. I will have a look.

Thanks,
Rory

[kentplums]

Sorry Ed
where abouts is the appropriate service advice? I'll get the hang of this one day!
cheers
R

[richrussell]

Welcome - these are a good radio to learn to restore on - the wiring and components are fairly accessible, and when working they sound good. I've got one in my dining room (because the cream and brown match the wallpaper and furniture )

But if it's humming like that, I wouldn't turn it on again until you've at the very least replaced 'that capacitor', and ideally any other capacitors that look bad (anything with 'Hunts' written on it, or coated in yellow wax). The electrolytics may well be OK, but the waxed paper ones will almost certainly not be.

Be aware that this is a live chassis set, so ensure it's not plugged in when you take the back off, as there is a risk of serious electric shock if you don't know what you're doing.

Read the guide, download the PDF service manual, work out what needs replacing, buy suitable capacitors from RS/CPC/Farnell/Maplin etc and get your soldering iron out. Once it's done, you'll have a decent sense of achievement and a nice sounding radio.

[Herald1360]

Originally Posted by richrussell

Read the guide, download the PDF service

Which is here:

http://www.service-data.com/product.php/2120/2902

for a couple of quid.

[kentplums]

Hi again,

PDF downloaded. I'm still not clear which THAT capacitor is; are we talking about C45?

Anyway, C62 on mine is a 47µf 350V "Ace" brand light blue electrolytic cap. The service sheet says it should be 0.01µf 350V, Is this OK?

So many questions!

Cheers,
R

[Herald1360]

The service sheet shows C62 is a 0.01uF filter across the mains just after the switch. Best thing to do with this is cut it out for now. The set will work without it and if it fails it could explode and damage something. It can be replaced eventually with a properly rated X class suppression capacitor. I don't think it can be the 47uF 350V part you describe as that would have exploded when hit with mains AC!

47uF 350V is a perfectly reasonable replacement for either of the smoothing capacitors C50, C51, and would probably be OK in the C61 position, though the circuit shows 8uF there.

THAT capacitor is C48 which if leaky can overload the output valve and transformer circuit.

C45 is another capacitor which can give problems with distorted FM sound if it's faulty and is notable mainly for the fact that its +ve end connects to 0V (chassis) rather than its -ve end.

[kentplums]

Thanks herald1360.

C48 on mine is a Metalmite 0.01µf 350v DC. What would be a 'modern' replacement and from where would be the best bet? Is polarity an issue with this cap?

Thanks for your time.

R

[Herald1360]

Any modern polyester or polypropylene 10nF 400V or higher capacitor will do. Axial types are nice for appearance but radial work just as well electrically.

One possible source is Cricklewood Electronics

http://www.cricklewoodelectronics.co...cat=151&page=1

though there are many others including the major suppliers like RS, Farnell etc etc.

[kentplums]

Thanks Chris
I've ordered a couple off ebay...hope I got it right...

2 x 1000pF (1nF) / 400V KP 2% PHILIPS HI END CAPACITOR (140775186518)

What could possibly go wrong ?

Rory

[Herald1360]

Perhaps the value? 10nF (0.01uF) is 10,000pF, not 1000pF

PM me your address and I'll bung a couple of 10n 400V in the post for you. I can probably find a 10n X-type while I'm at it.

You can send me a nice Christmas card in return!

Write it off to experience.....

[kentplums]

So I've accidently got myself 3 surplus 1nf caps! Could I use these in the FM tuner unit (C2,C53,C57) or would this be just opening a can of worms? As I appear be recieving nothing on the set I'll probably be working my way through the lot bit by bit.
HERALD 1360 your card's in the post!
Cheers
R

[kentplums]

Hi again.

Still on the Ferranti U1003.

I have 2 x 68uf 450V electrolytics.

Question 1. Could these safely replace the 2 x 50uf caps?(C50and C51)?

If the answer is yes, I would rather bypass the original big metal cap and install new caps under chassis.

Question 2. How?

Question 3. Simple or not simple?

Thanks in advance
R

[AC/HL]

The UY85 rectifier is OK for up to 100mF, so you should be OK. Disconnect the existing one and fit the new ones, how you do it depends on the space available and the size of your replacements, but it shouldn't be critical.

[Herald1360]

There's only a few things to watch if you relocate the big smoothers:

The common -ve terminals are connected to the chassis at the same point(s) and the positive output from the rectifier goes to the first capacitor +ve terminal then from the capacitor (not the rectifier cathode tag) to the smoothing resistors R26 and R34- this will keep ripple voltages to a minimum if there is more than about an inch of wire between the rectifier cathode and the capacitor. Also if the new capacitors are located away from the old ones keep any wiring carrying ripple current (mainly the rectifier and chassis connections to C51) well away from any low level audio signal wiring.

[kentplums]

Many thanks again
R

[kentplums]

Well I've fitted the 2 68uf 450v caps and it is now beautifully quiet. However I'm still at the stage where I can only get one MW station at low volume even when turned up full. Nothing at all on LW or VHF. On GRAM setting I get a good buzz when touching the sockets so the amp is presumably working fine. I'm waiting for a few more caps including the other larger electrolytics so I'm hoping one of these will give me a miracle cure.
Anything else I could consider looking at - I've cleaned the waveband switch to the best of my ability but it has been liberally WD40'd or something in the past by the looks of it.
Thanks
R

[alanworland]

Hi R,

I have been following you experiences with your set as I have the same model.

I have not put power on mine as yet as I have been changing a variety of capacitors but tonight I discovered a twin core screened lead from the wave change switch to be in very poor order and changed it as I felt sure it would have given problems (insulation fallen off exposing inner cores - ideal for shorts)

Might be worth a look?

Alan

[kentplums]

Will do
Thanks