Pilot Radio restoration

[Calmore]

I'm embarking on restoring a pre- war Pilot brand radio.
It has a massive double HT filter cap in the back, along with many other capacitors that look a bit aged.

My original plan was to replace the HT caps and many of the others (esp wax) with those yellow polyester ones from RS before powering up. I don't want the set to go 'bang' and take out other components.

But, the advice on a certain FB forum is not to do any precautionary replacements but just power the thing up and fault find from there.

What are the thoughts on here? I trust you guys more than the random 'experts' on FB!

[paulsherwin]

You will find lots of threads on cap replacement here if you search.

The issue is that all wax caps from before the 70s will be leaky, and they are extremely difficult to test anyway. There are two basic schools of thought. The first is to simply replace the lot, as this is good preventative maintenance and makes subsequent fault finding much easier. The second is to replace a few critical caps such as the output valve grid coupler and anything across the mains, then use standard fault finding techniques to replace other caps as needed.

As a general rule, only caps between 0.001uF and 0.1uF are likely to be bad. Smaller values will be mica or ceramic and probably OK.

[Calmore]

Thanks. That's pretty much the way I was going to play it. I couldn't see the sense in just plugging it in, especially after 80+ years as one shorted cap could take out loads of other components. A few quid spend on capacitors could save a bucket load of heartache..

[Sideband]

There are some who prefer to replace one capacitor at a time and test the radio between each replacement. I suppose that's fine if you are learning and want to get an idea of what the capacitors actually do. However I don't and never have done that. I always replace the lot (except in TV's which are far more complex and require a different technique).

[Calmore]

I'm with you. Replacing one at a time could result in even more work if something goes pop!

[Duke_Nukem]

Originally Posted by Calmore

But, the advice on a certain FB forum is not to do any precautionary replacements but just power the thing up and fault find from there.

Maybe re-read it, and snip the mains filter cap for starters and deal with the grid coupling cap.

Paul Sherwin has described two approaches people take. The third is minimum cap replacement to safely power up at which point you'll get an idea if the chassis is a reasonable bet or the fact that every darn coild in it is o/c, theb gradually replace all other wax/hunts caps as chances are if you want reliability/good performance then they WILL have to go. But if you do a mass cap replace and you dont know how to fault find then one mistake and you will be in a world of pain.

TTFN
Jon

[stitch1]

Originally Posted by Duke_Nukem

Maybe re-read it, and snip the mains filter cap for starters and deal with the grid coupling cap.

Paul Sherwin has described two approaches people take. The third is minimum cap replacement to safely power up at which point you'll get an idea if the chassis is a reasonable bet or the fact that every darn coild in it is o/c, theb gradually replace all other wax/hunts caps as chances are if you want reliability/good performance then they WILL have to go. But if you do a mass cap replace and you dont know how to fault find then one mistake and you will be in a world of pain.

TTFN
Jon

The certain FB site is part of this site and that wasn’t how I read the advice (from members on here) either.

At the end of the day you’ll learn what works best for you but I’m in no hurry to turn them over and move them on so I do the minimum needed to power up safely and see what’s what. With a lamp limiter and good sense of smell nothing should go pop, but there’s always the anticipation!

Enjoy.

John

[Calmore]

Thanks all!

I'm going to replace all the waxies, mains cable before power up and take it from there.