Circuit Board Blown

[normmcgarry]

I have a Jacuzzi J320 that is from.... 2002? It was inherited used from family for extremely cheap. Had a 50A panel installed outside and ran to it, and all has been well for about 3-4 weeks now.

We turned the temp down to 90 so the kids could get in and have fun. After they were done, I added some chlorine, turned the temp back to 100, turned the jets on, and next thing I know, I hear a loud pop and the breaker outside flips, and the two breakers on the main panel flip. I turned them back on, hot tub seems to be working ok at first glance. Hours later... the temperature is down to 89.

Anyway, finally found some time to crack the thing open and see what's going on, and the black wire terminal on the HEATER IN on the main circuit board was completely destroyed and blown out.

Now, I'm ready to pull the trigger on buying and installing a new board ($249 on eBay), but I want to make sure it isn't the heater that caused this and I'm going to repeat the destruction on the new board. Does anyone have any knowledge to where they confirm this is just the board wearing out, or if it is caused by the heater, or something else? Is there any diagnostics I can do to confirm anything?

I did unplug the black wires (which I'm guessing are negatives?) on both the HEATER IN and HEATER OUT terminals and connected them together. The heater started up, and actually heated the hot tub to 95 degrees before I turned it off and decided I didn't want to cause more damage, since I don't know the effect of bypassing the board in that scenario.

Thanks everyone. Pictures attached of the damage.

[Dr. Spa]

AC voltage has NO negative or positive. There's hot (or power) and neutral. If you spa is wired for 220 the heater operates off 2 hot legs (running at opposite phases).

[Spa Board Doctor]

This is a common problem with that series of PC Boards. The damaged relay and circuit board traces are repairable. The heater is not the cause of the failure.

[normmcgarry]

So this is just a board/relay malfunction? I will probably just replace the board, since I'm not that experienced with soldering. Just wanted to make sure my issue was isolated before I replace the board and immediately burned it out when I plugged it in.

Thanks everyone for your help. It is much appreciated.

[kafolske]

Did the new circuit board fix your problem?

I am having a similar problem and have a burned "N Heater IN" terminal. I tested the K7 and K8 relays and they seemed to function correctly and were not shorted. I also tested the heating element and it measured 10ohms.

Thanks,

Keith