Whatever you do, don’t touch the capacitors, especially if it’s an old TV, even if it’s unplugged. Could kill you. Old TV caps pack a serious punch (even when unplugged)
The big risk in old TVs was the enormous voltages in the CRTs (which acted as a capacitor and stored energy even when off, and even pick up energy from background sources)
Its always best to work out where the mains PSU is, and either cover/isolate it so that you don't touch it by accident. Even if turned off, there is a non-insigificant risk that there is either mains power lying around or some other large charge/current ready to bite.
THe back of the inlet is also tends to be a hazard, so be really careful around there too.
The other answer is "pliers."
(Make a connection across the terminals that have a voltage difference)
That kind of tester is usually built into a screwdriver and often comes free with some electrical items. They are maybe $2 otherwise.
[1] there are exceptions, e.g. older vacuum tube sets which used a mains-driven EHT circuit with discrete capacitors