A Marconi CR.100 dilemna.

[Yorkie]

This is the dilemna of 'conservation' v 'restoration' - the older a set is, the more I think we should be inclined to keep it as original as possible - for example, by leaving resistors in place that are perhaps 50% out of spec if the receiver works, rather than perhaps changing those that are just 20%+ out of spec. But if we want it to perform as it was originally intended to when it was 'factory fresh' that involves more drastic work. As far as waxies are concerned, they're known to become leaky in the elctrical sense in which case they fail to do the job they're there to do, namely, to allow AC signals to pass while blocking DC voltage. When that happens, we can get DC where we don't want it - typically on the grid of the output valve, which can damage the valve, the output transformer and the mains transformer due to excess current being drawn. Even worse if the receiver has a mains energised speaker in which the spekaer field coil doubles as a smoothing choke, and consists of thousands of turns of fine gauge wire (not relevant to the CR100 of course). The is why 'That' capacitor (the one on the grid of the output valve) has gained such notoriety. It's such a cheap job to change waxy caps that it's hardly worth the risk. The same applies to Hunts 'mouldseal' caps - the ones in a sort of brown plastic encapsulation which is often crumbling or cracked. (Many Eddystone receivers used little oval red caps - notorious for becoming leaky too).

Others may not see things my way, but for me, the priorities I follow are:

1) Safety.
2) Performance and future reliabilty.
3) Originality.

I place originality last, because above all the set must be safe, and if it's intended to use it, it must peform as originally intended.

The last thing on my mind is originality, especially when it compromises safety and performance.