Left town for Thanksgiving, came back home, checked the tub and I could smell an electrical burn. Tub is a Jacuzzi Corsica model 8200, old, but otherwise works. Opened the control panel and noticed that relay 1, was closed, no matter what the tub setting. Thought that wasn't right. Started to unplug devices from the controller and when I unplugged the thermostat (hi limit switch), the relay opened. I'm no electrician, but it seems to me that the thermostat (hi-limit switch) is shot. Does anyone have any input as to if I'm on the right track? I replaced the thermostat (hi limit switch) several years ago. Is it normal to only last a few years?

I don't know what you're looking at exactly, but if it's a Balboa system, then they use 3 relays in series to deliver power to the heater. One of them is called a hi limit relay, and is normally energized at all times as long as the 'hi-limit' temperature hasn't been reached. This circuit is independent of the rest of the temperature controlled relays.

In my opinion, what you observed is normal behavior.

You probably need to bark up different tree on this and figure out exactly where the smell is coming from first - ie, air out skirt well, power off and use a very good nose. Arbitrarily unplugging stuff is not going to help. You've got an excellent symptom to work with - a nasty smell. Find out exactly what component it's coming from and work back from there.

Pageup, I think you're correct with the Balboa system and the 3 relays in series. I wasn't aware that the first relay (hi limit relay) was energized all the time. I'll see if I can determine exactly what is getting hot and go from there. Thank you for the quick response.

Think I found the culprit:

Looks like I'll be doing some re-wiring later this week... yuck! But at least my tub (or house) didn't burn down!

Unfortunately that's not a balboa system, it's the dreaded 'Blue Box' controller of the 80's.

If the extent of the problem is limited to the rotten bus strip, consider your self lucky.

It's a really nasty design not supported anywhere - and you'll need a lot of time and patience to troubleshoot anything beyond a basic power issue.