Heat therapy systems

Gaymar TP-500: troubleshooting and error codes

The ServiceForge knowledge base holds 23 documented symptoms for the Gaymar TP-500, with 38 ranked causes, 47 diagnostic checks with test points and expected values, and 0 error codes. Each symptom below shows its causes and the first check; the rest is one connection away. Connect ServiceForge to your AI

Symptoms

Over temperature light activates unexpectedly patient safety

OVER TEMP indicator illuminates; pump and heater shut off during normal operation

Ranked causes

1. Manifold backup limit thermostat malfunction (common)
2. Well backup limit thermostat malfunction (common)
3. Low water level in reservoir (common)

First check

Verify reservoir water level

Test point: Side of pump reservoir
Expected: At or above operating level mark

1 more check with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Pump does not circulate fluid

No water flow from pad outlet despite pump running or operating

Ranked causes

1. Hose or pad blockage or kink (common)
2. Pump seal or impeller failure (occasional)
3. Return hose fitting orifice obstruction (occasional)

First check

Visually inspect hose routing

Test point: All hose sections
Expected: No kinks, folds, or sharp bends

2 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Reduced flow rate or no water flow caution

Water flow through pad is less than 9 gph minimum or completely stopped.

Ranked causes

1. Hose kinked or pinch clamp closed (common)
2. Connector not fully seated (occasional)
3. Insufficient water in reservoir (common)

First check

Visually inspect hose for kinks

Test point: Entire length of 10 ft dual hose
Expected: Hose straight, no visible bends or kinks

3 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Unit does not heat water high voltage

Water temperature does not reach set point or heater does not activate

Ranked causes

1. Temperature controller malfunction (occasional)
2. Heater element failure (occasional)
3. Well backup limit thermostat shutdown (common)

First check

Verify power supply to heater circuit

Test point: Circuit breaker CB1
Expected: No trip; 3A rating
Tools: Multimeter

2 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Water leakage onto floor caution

Water leaks from pump connections or hose when pump is operating or shut down.

Ranked causes

1. Pump positioned below pad level with overfill or multiple pads (common)
2. Improper connector disconnection (occasional)
3. Damaged or loose hose connector (rare)

First check

Compare pump position to pad position

Test point: Relative elevation of pump and pad(s)
Expected: Pump at or above level of all pads

2 more checks with pass and fail actions, 3 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Backup limit thermostat trip point test

Verify manifold and well thermostats open at correct temperature range when primary temperature controller is shorted out

Ranked causes

1. Manifold thermostat operating outside intended range (110°F to 117°F) (unknown)
2. Well thermostat operating outside intended range (110°F to 122°F) (unknown)

First check

Verify pump operating at setpoint temperature

Test point: Water temperature
Expected: 107°F ±2°F

5 more checks with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Leak test caution

Check for leakage from tray and reservoir joint after completing backup limit thermostat test

Ranked causes

1. Leakage from tray and reservoir joint (unknown)
2. Fill cap not tight or gasket displaced (unknown)

First check

Pressurize system and visually inspect for leaks

Test point: Tray and reservoir tray joint
Expected: No visible leakage after 3 minutes with unit tilted forward

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Poor pump motor performance or reduced flow caution

Motor runs but with reduced power, slower operation, or inconsistent performance.

Ranked causes

1. Reservoir overfilled (common)
2. Water quality issue (tap water used instead of distilled) (occasional)

First check

Check water level in reservoir

Test point: Side of pump body operating level mark
Expected: Water at operating level mark, not above

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Pump housing or internal parts damaged caution

Cracked or damaged plastic parts, dirt accumulation inside pump

Ranked causes

1. Cracked or damaged plastic parts (unknown)
2. Accumulated dirt inside pump (unknown)

First check

Remove pump cover and visually inspect internal parts

Test point: Inside of pump housing
Expected: No cracks or damage to plastic parts; no accumulated dirt

2 corrective actions and part numbers are in ServiceForge. Connect ServiceForge to your AI

Unit shuts off when tilted or moved caution

Heater and pump stop operating when pump is tilted more than 45 degrees from vertical

Ranked causes

1. Tip-over switch activation (normal safety function) (common)
2. Defective tip-over switch stuck in open position (rare)

First check

Verify pump orientation

Test point: Pump base on support surface
Expected: Pump positioned vertically or within 45° of vertical
Tools: Level or visual inspection

1 more check with pass and fail actions, 2 corrective actions, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Calibration: TP500/TP500C operating temperature

Unit temperature reading does not match expected 107°F ±2°F after 30 minutes stabilization at maximum dial setting

Ranked causes

1. R3 trim potentiometer requires adjustment (common)

First check

Verify pad is flat and warm

Test point: TPT9 float
Expected: at least 9 gph

3 more checks with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Circuit breaker tripped caution

The circuit breaker button has extended 1/4 inch, exposing a white band, indicating power interruption.

Ranked causes

1. Electrical fault or overcurrent condition (unknown)

First check

Inspect power cord for damage

Test point: Entire length of 18 AWG, 3 conductor power cord
Expected: No cuts, burns, or exposed wires

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Connectors cracked or damaged caution

Cracks, missing O-rings, or other damage to connectors

Ranked causes

1. Damaged connectors (unknown)

First check

Visually inspect all connectors

Test point: All hose and electrical connectors
Expected: No cracks, missing O-rings, or damage

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Current leakage excessive patient safety

Leakage current in any combination of heater and power switch positions exceeds 100 microamperes

Ranked causes

1. Excessive leakage current through insulation (unknown)

First check

Measure leakage current in all heater/power switch combinations

Test point: Chassis ground hole at hose connection
Expected: Maximum reading 100 microamperes or less; typical less than 30 microamperes, <=100 microamperes
Tools: Leakage current meter

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Flow rate test

Verify pump flow rate meets minimum specification with pad flat and warm at same level as pump

Ranked causes

1. Flow below 9 gph (unknown)

First check

Verify pad position and temperature

Test point: T/Pad and TPT9 float
Expected: Pad flat, warm (approximately 107°F), at same level as pump

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

Ground resistance out of specification high voltage

Ground resistance between plug ground pin and manifold block exceeds 0.5 ohm

Ranked causes

1. Inadequate ground connection (unknown)

First check

Measure ground resistance with meter

Test point: Ground pin on plug to brass manifold block hole
Expected: 0.5 ohm or less, <=0.5 ohm
Tools: Ground resistance meter

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Line cord physical damage high voltage

Cuts, cracked insulation, or defective strain reliefs on power cord

Ranked causes

1. Damaged power cord (unknown)

First check

Visually examine entire line cord length

Test point: Full length of power cord
Expected: No cuts, cracks, or damaged insulation

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Motor lubrication required caution

Pump motor by Uppco requires oiling every 6 months to prevent seizure

Ranked causes

1. Pump motor by Uppco needs preventive oiling (common)

First check

Identify motor manufacturer on bearing housing

Test point: Top bearing housing
Expected: Jakel (no oiling required) or Uppco (oiling required)

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

OVER TEMP light illuminated patient safety

The OVER TEMP indicator light is glowing, indicating the pump and heater have been turned off due to exceeding high temperature limit.

Ranked causes

1. High temperature limit thermostat tripped (common)

First check

Verify temperature setpoint setting

Test point: Temperature setting key position
Expected: Setting between 85°F to 107°F (29.4°C to 41.7°C) as prescribed

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Plug defective or loose high voltage

Damaged plug, wire breakage, or loose terminal screws on power plug

Ranked causes

1. Defective plug or loose terminals (unknown)

First check

Check plug condition visually

Test point: Power plug
Expected: Plug in good condition, no wire breakage or loose terminals

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Switches or controls defective caution

Switches or control settings not functioning properly at any position

Ranked causes

1. Defective switch or control (unknown)

First check

Operate all switches and controls

Test point: All switches and control settings
Expected: All switches and controls function properly at all positions

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Tip-over switch not functioning patient safety

Tip-over switch fails to deactivate heater when unit is tipped 45 degrees

Ranked causes

1. Defective tip-over switch or PC board (unknown)

First check

Set temperature to maximum and verify heater indicator is on

Test point: Temperature dial and heater indicator lamp
Expected: Heater indicator lamp is on at 107°F setting

1 more check with pass and fail actions, 1 corrective action, and part numbers are in ServiceForge. Connect ServiceForge to your AI

TPC1 test cover connection color mismatch caution

Test cover wiring connections do not match T/Pump wiring colors

Ranked causes

1. Incorrect wire color matching (unknown)

First check

Visually verify wire color matches between test cover and T/Pump

Test point: TPC1 alligator clips and T/Pump terminals
Expected: All wire colors match between test cover and pump

1 corrective action and part numbers are in ServiceForge. Connect ServiceForge to your AI

Community

0 fixes logged by technicians through their AI, with outcomes, for this model.

ServiceForge knowledge base record. Field-unverified unless technicians confirmed it. A teaching summary of the record, not a service manual. Export 2026-10-14.