Static Electricity is always being generated around us, even at those times of the year when we don't get zapped walking across a rug and touching something.

Like all state-of-the-art circuit boards, the hot tubs circuit board can be damaged by unnoticed static electricity. Damaged is the key word. Sometimes a board which has been subjected to ESD will fail immediately upon being put back into service. Usually a board will operate for a few days, or months, then fail.

- If the hot tub runs only a few days, you feel you did a poor job of servicing your spa. - If the hot tub runs only a few months, you feel the circuit board is low quality.

2. Avoiding ESD Damage

We don't prevent static charges from building up within us as we go about our jobs, so we must do things to protect circuit boards from getting zapped.

1. Never transport or ship circuit boards - Good boards or bad boards - except in static protective bags.

2. Never remove the board from the static protective bag unless you are ready to install it in the hot tub.

3. After removing the bad board from the hot tub, A) lay it on the ground. B) remove the replacement board from the static protective bag. C) lay the replacement board on the ground. D) place the bad board into the static protective bag. E) install the replacement board into the hot tub.

3. What about Wrist straps and special mats?

The purpose of these items is to keep the technician, the work surface, and the circuit board at the same electrical potential and to drain into ground any static charges which might build up. Proper use of the wrist strap and a special mat guarantees maximum protection against ESD damage.

4. Must wrist straps and mats be used when replacing a circuit board?

No, if you keep the spare board in the protective bag during transport and you observe a few simple techniques during replacement.

The possibility of ESD damage to the circuit board during replacement will be minimal because of the hot tub's design and the way you normally work on it. Touching the grounding lug will drain all built-up static charges from your body much like a wrist strap would. Laying the bad board on the ground will tend to keep it neutral. Touching a finger to the grounding lug immediately before removing the good board from the bag will drain any charges built up by the rustling of your clothes. Laying the good board on the ground after removing it from the protective bag, will tend to keep it neutral. Another quick touch of the grounding lug before picking up the bad board will again drain any built up charges. Slipping the bad board into the bag will allow it to be transported safely. Another quick touch of the grounding lug before picking up the replacement board will again drain any charges built up by the rustling of your clothes. In the process of installing the new board you and the board will be grounded to th e load box or grounding lug, draining off charges you may build up during installation.

Note: When Handling Cicuit Boards and/or EPROM Chips, you must be grounded at all times preferably either by a wrist strap or anti-static mats. Static discharge can cause failure of these sensative components which could void the warranty.

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2. Check for power at transformer secondary. If power exists at transformer secondary, problem could be panel or pc board. Try a spare panel first.

3. If no power exists at transformer secondary, check for power at transformer primary. If power is present at transformer primary but not at transformer secondary, replace transformer.

4. No power at transformer primary indicates either an open 1.25 amp fuse ( located on pc board ) or a blown system fuse ( located in fuse block in control box ) or a lose or disconnected wire.

NOTE: If 1.25 amp fuse is blown it is recommended you replace the pc board.

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It is important to know how difficult intermittent problems are to locate. You will be doing a series of things to eliminate the problem.

Standard Approach

1. Check crimped wire connections to the heater element. If burned, replace heater element wires. Verify heater element connections are good on circuit board.

2. Check flow / pressure switch for proper and consistant operation.

3. Clean connections where panel plugs into board.

4. If all above items check out, has error code Sn3 ever displayed on the panel. If Sn3 has displayed, replace the temperature sensor.

5. If spa is still malfunctioning, contact a service technician.

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Standard Approach:

Put hot tub in standard mode and set temperature high enough to initiate a heat call. Remove power to hot tub then plug in a spare control panel. Turn power on. Does indicator work now?

A. If NO: Call service technician.

B. If YES: Replace panel.

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Error Condition: Pump running, flow switch open.

Standard Approach:

1. Is voltage present between flow / pressure switch terminals? ( check from one terminal to the other.)

A. If YES: Remove filter from spa and run spa without filter. If this fixes the problem, replace filter. If removing filter does not correct problem,replace flow / pressure switch.

B. If NO: Check for voltage where wires come from and go to circuit board. Is voltage present? B-1. If YES: Replace wires to flow / pressure switch. B-2. If NO: Replace circuit board.

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Error Condition: Circuit board trying to activate pump, flow / pressure switch open.

Standard Approach:

1. Is there correct voltage coming to the hot tub?

1A. If NO: Call Electrician

1B. If YES: Put hot tub in standard mode and set temperature high enough to initiate a heat call (wait 20 to 30 seconds for circuit board to respond).

2. Is proper voltage present at the circulation, low speed (heat pump) terminals?

2A. If NO: Check pump fuse for blown. If pump fuse is not blown, ( turn power off to spa ), Try unplugging the temp sensor, turn power on to spa to see if spa will boot and display an error code. If spa displays an error code, replace temp sensor. If spa does not display an error code, replace board.

2B. If YES: Is connection good between pump and circuit board? If yes, replace pump.[/b]

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Error Condition: Pumps off, flow or pressure switch closed.

Standard Approach:

1. Turn power off to the hot tub. Remove wires from flow / pressure switch. Check for continuity between terminals of flow / pressure switch. If continuity exists, replace switch with new. If continuity does not exist, replace board. (the flow / pressure switch should only be closed when the pump is running and proper water flow is present.)

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Configuration: The water heater will not operate with both pumps running simultaneously in high speed when the circuit board is configured for low amp source voltage.

Standard approach:

1. Put hot tub in standard mode and turn up temperature to initiate a heat call (wait 20 to 30 seconds for circuit board to respond). Is proper voltage present at the heater terminals or outputs?

A. IF YES: Is there current draw from the heater element? A typical heater element 5.5kw at 240 volts will draw approximately 20 to 25 amps. (use a clamp on amp meter around one of the heater wires.) Current draw is proof the heater element is working. Make sure the spa water temp continues to rise over time. Typical heating time for 5.5kw heaters at 240 volts is 4 to 6 degrees per hour.

B. IF NO: Is proper voltage present at source terminals and at board where source terminals attach to the board? 1. If no: source voltage problem. Contact an electrician. 2. If yes: Replace circuit board.

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All of the components in an electro-mechanical system are switches. They are either on or off. How they are controlled and what turns them on or off varies between designs and manufacturers.

The following are simple overviews of the most common components.

Never test components with power applied to the hot tub. Be aware your system may vary.

Thermostat

A thermostat is a simple switch. It is either on or off. Unlike a light switch you turn on by hand, the thermostat has a sensing bulb attached to a capillary tube which is attached to the thermostat switch. The sensing bulb and capillary tube are gas filled. As the gas warms, it expands and activates the switch. The knob on the switch, tells the switch at what level the gas temperature should activate the switch.

Testing: Turn spa power off and remove wires from thermostat. Turn Thermostat up as far as it goes. test for continuity across the two terminals using a voltmeter (multimeter). If continuity is present, and spa water is below 104 degrees, Thermostat is working at that temperature. If no continuity is present, the thermostat has lost calibration and should be replaced.

If Spa water is 104 degrees or above and there is no continuity across thermostat, the thermostat is going to allow the water to continue to heat. Watch carefully, if the water temperature increases above 104 plus or minus a degree or two, replace the thermostat. Hot Tubs and Spas should never be used at temperatures above 104 degrees.

Note: Thermostats may test properly at some temperatures but not at other temperatures. They can lose upper or lower end calibration. If you find a thermostat not working properly or working erratically , no matter what the temperature is, you should replace it.

High - Limit Switch

A high limit switch is exactly that. A switch. It is either on or off. High limit switches are safety switches that will turn power off to the spa heater in the event the water temperature exceeds 118 degrees. Now, you need to be aware that by the time a high limit switch trips ( or opens ) to shut power off to the spa heater, the water temperature is high enough to burn your body severely. Always use a working thermometer in your spa and always check the temperature prior to entering the water.

Testing: Turn power off to the hot tub. Remove wires from the high limit switch.

If water is below 104 degrees, There should be continuity through the switch. Test using a multimeter and touching one lead to one terminal of the switch and the other lead of the meter to the other terminal of the switch. Continuity means that the switch is closed and will allow power to flow through it.

If there is no continuity, check the red button and see if it has popped out ( tripped to shut power off ).

If the red button is out, the high limit has tripped. This can be caused by several things, but basically the water is too hot. The high limit sensing bulb does not test the actual spa water temperature but instead tests the water temperature in the heater vessel. A plugged filter not allowing water to move fast enough through the heater vessel can cause a high limit switch to trip.

If the red button has not popped out, and there is no continuity between the high limit terminals. The high limit is bad and should be replaced.

Pressure Switch

A pressure switch is another switch used to control the heater of the spa. It tells the system that it is either ok for the heater to come on or that it is not safe for the heater to come on.

Testing: Power must be on and spa running to test a pressure switch. There are two terminals on the pressure switch. Turn power off to spa, remove wires from the pressure switch, tape the ends of the wires to avoid shorting when power is turned on. Turn power on to spa, test for continuity between the two terminals of the pressure switch. Using a multimeter, place one lead on one of the terminals and the other lead on the other terminal.

If you have continuity, the pressure switch is activated, telling the system it is ok for the heater to come on.

If there is no continuity and the pump is running, and you have adequate water flow, the pressure switch is not activating and should be replaced.

Turn power off to the hot tub. Retest pressure switch. When testing for continuity with the spa off (no pump running) you should not have continuity across the switch. If continuity is present, replace the switch. it is stuck in the closed position

Contactor

A contactor is a switch controlled by a coil. When there is voltage across the coil it will cause the contactor contacts to pull in allowing power to flow from one side to the other completing a connection.

There are usually 4 large connections on the top of the contactor. These are the contact connections. two are input and two are output. When voltage is applied to the input contacts and the coil is energized the contactor will close a bridge between the input and output contacts completing the connections and allowing power to flow through it.

Each contactor has a coil that controls it's operation. One side of the coil will connect to the common or neutral wiring. the other side will connect through switches like the thermostat, high-limit and pressure switch. If all switches are closed, the coil will energized and close the bridge on the contactor.

Testing: You must have power on to test a contactor operation. Extreme caution should be taken.

Test for voltage at the input terminals. Using a multimeter place one lead on one of the input terminals and the other lead to common or neutral on the source incoming power bar.

If voltage is present, check for coil voltage. Coil voltage could be any of the following:

120 volts AC

240 volts AC

120 volts DC (rarely but some manufacturers use it)

Once you know the coil voltage (should be stamped on side of contactor) you can test the coil by placing one lead from the multimeter to one side of the coil and the other lead from the multimeter to the other side of the coil. Coil connections on the contactor usually look like spade connectors and are on the side of the contactor.

If you have proper voltage, test for voltage on theinput and output contacts of the contactor. You should have the same voltage on both sides of the contactor when the coil is energized. If voltage is different or no voltage is present on the outputs when voltage is present on the inputs the contactor is bad. Replace it.

If you do not have proper voltage on the coil connections, you can not test contactor operation. Follow control circuit for coil connections.

Air Switch

Air Switches are another type switch found in electro-mechanical control systems. They are activated by air pressure from an air button usually located at the top of the spa for easy access to the user. Air switches remove the need for electrical buttons at water level for safety reasons.

Air buttons usually have 2 or 3 connections. We will look at a 3 connection button for a two speed pump.

Connection one is "Common" ( comm ) power into switch.

Connection two is "normally open" (NO) High speed pump.

Connection three is "normally closed" (NC) Low speed pump.

Testing: If power is available at terminal 1 on the air switch, power should be available at terminal 3 of the air switch. Pressing the air button should activate the air switch and move the power from terminal 3 to terminal 2.

Using a multimeter place one lead on the common of the source power bar of system and one lead on the "comm" terminal. If voltage is present, place the lead from terminal 1 "comm" on terminal 3 "NC".

If voltage is present, press air button and check switch operation. Voltage should disappear from terminal 3 and appear at terminal 2 "NO".

Malfunction identification: Faulty switch, won't switch when button is pressed or damaged air tube, air leaks out instead of activating air switch.

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We will be examining a simple design system. Your system may be extremely different depending on what equipment is being run by the controls.

ie:

1 - pump system 1 - pump with blower system 2 - pump with blower system 2 - pump with blower and circulation pump.

Most electro-mechanical systems use a two speed pump as the main pump. Low speed for circulation and heating and high speed for jets.

However, some systems use a single speed pump for circulation and heating and separate single speed pump for jet action.

We will be describing a single two speed pump system with a blower.

You should be able to troubleshoot a larger system by using this description along with the seperate component testing topics.

Spa will not heat - no heat light

Symptom: Spa water is cooler than set temperature.

Condition: Spa heating pump is running, spa heat indicator light is not on and spa is not heating.

1. Step one in a "NO HEAT" situation is always to check the filter. Is the filter clean and clear of debris? Remove filter from filter canister and replace lid to filter canister. Run spa without the filter in place, set thermostat high enough to call for heat. Is heat indicator light on?

If YES: check for proper voltage at heater element terminals. if proper voltage is at terminals, check for current draw using a clamp on amp meter around one of the heater wires. If the amp meter shows current draw, the heater is working. Replace filter with new.

If NO: Check for proper voltage at heater terminals. Is proper voltage present?

If YES: Check for amp (current) draw by using a clamp on amp meter on one of the heater wires. If heater element is drawing amps, heater is working. Replace indicator light. If heater is not drawing amps.

a. Check voltage across pressure / flow switch. Test by using a voltmeter - one lead to one terminal of the switch and one lead to the other terminal of the switch. If voltage is present, the switch is open. The switch is saying there is not enough water flow through the system to activate the heater. Check water flow, if water flow is adequate, replace the switch. If no voltage is present, the switch is closed and saying there is adequate water flow through the system to activate the heater. Problem lies elsewhere.

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No voltage across pressure switch: Pressure switch closed.

A. Follow the heater wires to the next connection. This should be a contactor. Check for voltage at the two terminals of the contactor that the heater wires connect to. If voltage is present, replace wires between contactor and heater. If no voltage is present, check for voltage on the other side of the contactor. The two terminals that look like the terminals the heater wires are attached to. These are the inout side of the contactor. Is voltage present on input of contactor?

A-1. If YES: Contactor is not pulling in. Check the contactor coil voltage. Could be 120 AC volts or 240 AC volts and some systems use 120 DC volts. Is proper voltage present at contactor coil connections? These connections are the small usually spade connections on the sides of the contactor.

A-1-a. If YES: Replace contactor

A-1-b. If NO: Test the coil control circuit. The side (spade) connections on the contator. One side will go to common wiring, the other side of the contactor is the control circuit side and goes to the high limit switch and thermostat. Test the high limit and thermostat the same way as the pressure switch. One meter lead to one side of the switch and one to the other side of the switch. If you find voltage, you have found the problem component, replace it.

A-2. If NO: Follow the large wires to their next connection. If voltage is present at next connection, replace wires. If no voltage is present follow wires to their next connection. When you find voltage, you have found the problem component, replace it.

Remember these are guidelines and there is no simple way to explain tracing a problem down in an electro-mechanical control system. Qualified service technicians should be the only persons dealing with this type troubleshooting. This is a simple electro-mechanical heating diagram to show the basic troubleshooting steps only.

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