Why does my 1989 TV have two separate power buttons on the front?

Question

First, there is a big, square one always visible, which seems like the "master" power button (besides the cable). It is pressed in and you clearly "feel" that the TV is turned off.

Then, there is a small one, normally hidden inside the hatch which you open (but mine is gone, so it always shows for me), which appears to mimic the power button on a remote controller (which is also lost in my case). If you press it, the TV also "kinda" shuts down/turns on, perhaps slightly quicker in response.

Why have that secondary power button on the TV itself? Should I be using it instead of the main one? Am I doing something bad by always using the main, big one? Am I exhausting the TV somehow by using it? Is the small one more like "turning off the screen only" or something? Some sort of "stand-by" mode?

Note that far from all buttons on the remote controller has a version on the TV itself. For example, there is no "mute" button on the TV itself -- only on the remote controller. (I only know this from knowing that the TV has a "mute module" card and seeing a picture of the remote controller.)

It doesn't at all take long for it to "boot up" from off when you press the big button, so I see virtually no point in terms of "saving time" either. This is a real mystery to me. I've never seen a TV with two power buttons on the TV itself like this.

Answer 1

The big button connects/disconnects the TV power supply to the AC mains. This is necessary so 1) you do not kill yourself while opening up the TV for service, in the event you forgot to unplug it first (BTW grounding out the high voltage supply for safety purposes is also necessary in this case, but it's easily done) and 2) you can shut off all the power to the TV in case it catches fire.

The little button just toggles a master reset line on the microcontroller that manages among other things how the remote communicates with the sensor on the TV. If anything (like a stray neutrino from the core of the Andromeda galaxy) flips a bit in the TV's control circuitry and scrambles its brains, then you can do a "soft reset" by hitting that little switch to unscramble things.

Since this TV has a hot-filament picture tube instead of a flat display, note that toggling the AC mains will thermally cycle the tube's electron gun filament, which contributes to shortening the filament's useful life. In this case, you don't want to flex the filament every time you do a soft reset, and so a separate button would be provided for that purpose.

Answer 2

• The main power switch completely powers down the device and isolates it from the mains.
• The other button switches the device in and out of standby.

Standby mode powers down most of the circuitry but leaves enough running that the remote control can wake it up. Some models may have kept the tube heater on - possibly at reduced power - to give a quick turn when asked.