Extending capacitor lead length

[SurreyNick]

Hi

I have to replace one of the paper capacitors in my receiver but the leads on the replacement capacitor aren't long enough. Is it simply a matter of soldering an extension wire one or both cap leads?

Thanks

Nick

[marconi_pete]

Yes you can do that. I'd also use some heat shrink sleeving over the extension join so it can't come into contact with other components in close proximity.

[SurreyNick]

Thanks. I will do exactly that.
Nick

[Herald1360]

If it's the reservoir or smoothing capacitor in the PSU section just extending leads may increase ripple a bit. Depending on location and circuit configuration try to bring the input from the rectifier side onto the capacitor directly and take the output DC from the capacitor away on separate wires- a four terminal connection.

[SurreyNick]

OK Chris. I don't think it is. But would you have a quick look at the wiring circuit attached? It's cap C15 which on the trader sheet (under chassis schematic) shows it going from pin 2 of valve 2 to pin 3 of valve 3. But as you can see from the photo it actually goes to pin 3 of valve 4.
Nice and confusing for a complete novice like me!
Thanks
Nick

[marconi_pete]

Hi Nick,

I don't think you need to worry. Just had a look at the circuit diagram in the trader sheet and it's not a reservoir cap or smoothing can. You should be fine. Just be sure to use some heat shrink sleeving over the extension join, to avoid any contact with other components in the circuit. Sometimes the actual circuit in front of you does vary ever so slightly with the trader service sheet. It can be confusing granted. We've all had it happen at some time or another.

Regards,
Peter

[Station X]

Looking at the circuit, C15 is connected from V3 anode (pin 3) to the tone control.

Looking at the wiring drawing, C15 is connected from V3 anode (pin3) to V2 (pin 2), which is a spare pin. There'll be a wire from there to the tone control.

As you say, your C15 goes to pin 3 of V4, which is its anode.

It looks like either the component has been wrongly wired or the tone control circuit has been redesigned to operate on the output valve. The main thing is does the tone control work?

[SurreyNick]

Good question Graham. Unfortunately, I have no idea. The set was in a dreadful state when I got it. Rusted to hell, half full of a forest floor and enough mouse droppings to compost my garden! Working? I think it must have been unemployed since 1950!. I must be a complete fool to take this on as my first ever project. I took copious photos and have completely stripped it. I am now rebuilding it as per the original (photographic) layout. I have absolutely no idea if it's going to work though! The only thing in my favour is my ****** minded determination to restore it. But it is a case of the blind leading the long dead
Nick

[Heatercathodeshort]

Hello Nick,
I have used this method of extending component leads for many years. It was used by PYE in their television receiver production line for decades. It only takes a few seconds to wind the little coils around a mini screwdriver or thin rod. Thin tinned copper wire is ideal and tins easily. Can be used on all components and leads with no fear of a dry joint.
I bet you get that wreck working! It's always the messy ones that work!
Regards, John.

[SurreyNick]

Oh, that's excellent John. Thanks
And thanks for the vote of confidence too
Nick

[jonnybear]

What you need to be careful of is a lot of these old manufacturers used spare unused valve base pins as anchor points,this was OK for the valves used at the time,but some replacement & foreign valves use these pins and are internally connected, which can cause a problem, it pays to check with valve manufacturers data when rebuilding, another thing that can happen is set makers using internally connected pins for anode, cathode, grid connections, and later valves have no connection to these points, giving you faults that you would not normally happen.
john

[G6Tanuki]

The little-springy-coils approach is a good one - another technique I used involved very short lengths [1/4 inch or so] of small-bore copper or brass pipe from a model-maker's shop - pop both ends of the wire into the pipe, nip it up with a pair of thin-nose pliers, a touch of solder. Job done!

(put Systoflex sleeving or heatshrink over the extended lead if you want it to look a bit neater).

[JoshuaThorne]

What gauge and variety of wire would you recommend for extending capacitor and resistor leads?

[McMurdo]

I've always used 20A fusewire but 30 may be closer to vintage components. You can get all manner of gauges easily, I think my last lot came from CPC or Farnell but Brocotts do it too amongst many others.

I do a similar thing to HKS but I make 2 little hooks on the ends of the splices and solder those together, using heatshrink up to the required length.

[Herald1360]

For similar gauge wire to the components themselves I would think one of 20, 22, 24AWG tinned copper wire would be a good match but any odd bits of the same sort of size will be fine. Off cuts from other components can always be useful.

[JoshuaThorne]

Understood. Thank you very much, guys.

Would the tinning get in the way of proper conduction?

[Philips210]

Hi.

I always use John's method. It provides a a decent area of contact and is mechanically good as well. The little wire coils method is particularly good if several connections have to be made to one point. The coil easily accommodates the component leads and takes solder very well. It's very satisfying watching the solder flow around the component leads in the coil and you know that it will be an excellent joint.
I've sometimes used this method to made a quick prototype circuits as well.

Regards
Symon.

[G8HQP Dave]

Originally Posted by JoshuaThorne

Would the tinning get in the way of proper conduction?

No, the tinning is there to aid conduction by making it easier to get a good solder joint. An exception would be if you are working at UHF or microwave frequencies, but I suspect you are not?