new to me 96 hotspring soverign w/110 power. when plugged in the (heater) circ. pump runs and the tub lightbulb comes on but nothing else will come on. I've checked the boards and didn't notice any obvious damage. fuses are fine. the relay's dont appear to be switching on at all, but they do have power. I jumped the switches for testing the motor and heater and they appear to be working. the flow switch seems to be operational also. I'm thinking possibly a bad thermostat board. if anyone has any ideas on how to troubleshoot or has had similar problems let me know. your assistance is appreciated in advance. a pic of the box is attached

If the jets are not coming on, it's likely just a bad high-limit thermistor (temp sensor).
Is the power l.e.d. on the main display working?

If it is flashing, it "thinks" is has overheated, and has shut of all functions except the light and circ. pump.

If it's burning steady, ignore the rest of this post...

If it's out entirely...read on.

If you have an ohm meter, set it on 20k, and test resistance on the thermistors. They should read within +- 0.2 of each other. The control thermistor plugs into the top, the high limit thermistor plugs in just below it, and the flow/sw plugs in below that one.

If you don't have a digital meter that has a 20k setting, you are out of luck for this test.

An unplugged high limit thermistor will cause the same issue.

It's possible the high-limit PCB took a dump, but much more likey it's the high limit thermistor. Retails around $16.00

If the control thermistor craps out, it simply won't heat, or overheat. The jetswill still work fine.... same with the electronic thermostat.

BTW- the elec. high limit is re-set simply by powering the unit down for about 10 seconds, then tuning it back on.

Just go for the high limit thermistor first, but be carefull.... The no-fault 1500's heater housings have a tendancy to crack along the seam when you screw the new thermistor in. DO NOT overtighten. Use the same O-ring. If you see a small drip, the housing may have cracked.... not too expensive, just an annoyance at breaking something that wasn't broken before. Silicone and curing time *might* repair it, but replacing the would be reccomended if it's cracked.

Good luck

~Swine

I tested the thermistors, one read 7.90 ohms and the other read .93 ohms which is much greater than the +- .2 variance you advised. the thermistor that connects to the termostat control via the yellow and blue w/white reads 7.90 and the other thermistor that connects to another c board via black w/white and red w/white reads the .93. the only led light that comes on is the one that is next to the push bottons in the front, (only for two seconds when powered up)the other led light that is mounted in the plastic dial pad use to blink but now it doesn't come on at all. which thermistor should i replace or should i replace both. Is there a way to jump these switches for testing the board to see if it's bad?
Thanks again in advance Swine.
Bummer

Just got your PM- Congrats on fixing it and enjoy!

btw- that .93 reading on the high-limit thermistor equates into about 250F, hehe

~Ben