Should a variac always be used when beginning a new project? I have 2 16" zenith porthole tv's and a 12" zenith porthole that I hope to restore. If I replaced all of the weak or shorted tubes and wanted to see how the tv's performed before I recapped them, would a variac be the best way to turn the tv's on? Is what is referred to as a safe start? I'm trying my best to learn about the restoration process so any advice is appreciated.

I don't have a variac, so I just pull the horizontal output tube and turn it on. While it's warming up I monitor B+ on the meter, and if that's OK I put the HOT back in and try again. Generally though, I don't get any horizontal or vertical on sets with POI caps, so I end up having to do a lot of work before I can even get a 'health check'. Then I got the CTC-9, which worked with no parts replacement at all.

Using a variac is the accepted method for powering up a set. You can bring it up slowly that way while watching for any problem issues. Pay particular importance to filter cans to see if they are generating excessive heat while you slowly raise the line voltage. A good rule of thumb would be to start at about 50% of line voltage. Then increase 10 volts every 5 minutes till you reach full line voltage. Check for heating of the cans at each increment.

It is also useful in sets where you replace the selenium rectifiers, with more efficient silicon diodes. The silicon diodes will produce higher B+ voltage than the seleniums that you replace, and it is nice to be able to adjust the line voltage to achieve the correct B+ while working on the set.

In sets where I replace the seleniums, the last step in my restorations is to add a droping resistor in the B+ ckt to re-establish correct B+ at normal household line voltage.

Personally I NEVER run a set for any length of time until it is fully re-caped, including restuffing ALL filter cans. Lots easier to fully restore a set than to try and find a bad old component later on after it fails. And unless you are very lucky it probably will fail eventually.

Good luck and get a variac. And if you are working on a set that does not use a power transformer, you should also get yourself an isolation transformer. They are a good investment

good point about the iso. I have a combonation variac and isolation transformer with built in amp and volt meter.

We always used a variac on solid state sets after a power supply or horizontal problem.
Say you replaced a shorted horizontal output transistor, the safe bet was to bring it up slowly keeping an eye and ear and most of the time if there were other issues that caused the transistor to fail they would show up before the new one shorted again.

Tubes arnt nearly as fragile, I never use a variac on tube equipment. You just got to keep an eye out for tubes red plating or capacitors getting hot.

I wouldn't start an old set that's been sitting for decades without some sort of soft start.

While it's true you would probably notice anything amiss before it damaged something there's always a possibility you won't.

For example, a 5U4 tube can be destroyed instantly by a short in the B+ line, power transformers can overheat quickly, Selenium Rectifiers stink to high heaven if they overload or short, plus who need the shock of having something like a capacitor go pow with your face a foot away from it.

You can make a cheap Soft Start device with an old multi light bathroom fixture and 4 100W light bulbs.
Just wire the four bulbs in parallel on one side of a power cord, then you just screw in one bulb at a time, 100 watts should come on brightly then dim to 1/2 -2/3s quickly, 200 watts should dim even more, if you reach three bulbs and they are all still lit more than a dull glow you have a short somewhere.

Some sets like a big Dumont may require more wattage (just get bigger light bulbs) but you'll get the feel of it quickly enough.

The variac will also give the electrolytics time to reform and reduce the risk of them shorting. You'll still need to replace the electrolytics even if the set works to a degree.

Electrolytics are liable to die a quick death if woken up too quickly after years of idleness.

John