FR FieldReady Academy
Surgical tables

Skytron 3501B: troubleshooting and error codes

The ServiceForge knowledge base holds 52 documented symptoms for the Skytron 3501B, with 207 ranked causes, 78 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

Back section function moves improperly patient safety

Back section articulation slow, jerky, or unresponsive in one or both directions

Ranked causes

  1. 1. Incorrect speed adjustment (common)
  2. 2. Spool valve not centered (occasional)
  3. 3. Defective check valves (occasional)
  4. 4. Low on oil (occasional)
  5. 5. Pinched hose (occasional)
  6. 6. Defective mini-valve (occasional)
  7. 7. Pressure relief valve not set properly (occasional)
  8. 8. Defective solenoid (occasional)
  9. 9. Defective relay box or pendant control (occasional)
  10. 10. Kidney bridge raised (occasional)
  11. 11. Loose retaining hardware (occasional)
  12. 12. Microswitch out of adjustment (occasional)
  13. 13. Loose table top (occasional)

Leg function moves improperly patient safety

Leg section articulation slow, jerky, or unresponsive in one or both directions

Ranked causes

  1. 1. Incorrect speed adjustment (common)
  2. 2. Spool valve not centered (occasional)
  3. 3. Defective check valves (occasional)
  4. 4. Low on oil (occasional)
  5. 5. Pinched hose (occasional)
  6. 6. Defective mini-valve (occasional)
  7. 7. Pressure relief valve not set properly (occasional)
  8. 8. Defective solenoid (occasional)
  9. 9. Defective relay box or pendant control (occasional)
  10. 10. Loose retaining hardware (occasional)
  11. 11. Microswitch out of adjustment (occasional)
  12. 12. Loose table top (occasional)

Slide function moves improperly patient safety

Slide motion slow, jerky, or unresponsive; table does not slide smoothly toward head or foot

Ranked causes

  1. 1. Incorrect speed adjustment (common)
  2. 2. Spool valve not centered (occasional)
  3. 3. Defective check valve (occasional)
  4. 4. Low on oil (occasional)
  5. 5. Pinched hose (occasional)
  6. 6. Defective mini-valve (occasional)
  7. 7. Pressure relief valve not set properly (occasional)
  8. 8. Defective solenoid (occasional)
  9. 9. Defective relay box or pendant control (occasional)
  10. 10. Loose retaining hardware (occasional)
  11. 11. Microswitch out of adjustment (occasional)
  12. 12. Loose table top (occasional)

Back section or trendelenburg flex function moves improperly patient safety

Flex system slow, jerky, or unresponsive; back section and trendelenburg not coordinating

Ranked causes

  1. 1. Incorrect speed adjustment for flex, trendelenburg, or back section (common)
  2. 2. Spool valve not centered (occasional)
  3. 3. Defective check valves (occasional)
  4. 4. Low on oil (occasional)
  5. 5. Pinched hose (occasional)
  6. 6. Defective mini-valve (occasional)
  7. 7. Pressure relief valve not set properly (occasional)
  8. 8. Defective solenoid (occasional)
  9. 9. Defective relay box or pendant control (occasional)
  10. 10. Kidney bridge raised (occasional)
  11. 11. Worn ball joint or retainer nut (occasional)

Kidney lift moves improperly caution

Kidney lift cylinder does not move smoothly or at incorrect speed during operation

Ranked causes

  1. 1. Incorrect speed adjustment (common)
  2. 2. Spool valve not centered (common)
  3. 3. Defective check valve (occasional)
  4. 4. Low on oil (common)
  5. 5. Pinched hose (occasional)
  6. 6. Defective mini-valve (occasional)
  7. 7. Pressure relief valve not set properly (occasional)
  8. 8. Defective solenoid (occasional)
  9. 9. Defective relay box or pendant control (occasional)
  10. 10. Bypass valve out of adjustment (occasional)

Trendelenburg function moves improperly patient safety

Trendelenburg position change slow, jerky, or unresponsive in one or both directions

Ranked causes

  1. 1. Incorrect speed adjustment (common)
  2. 2. Spool valve not centered (occasional)
  3. 3. Defective check valves (occasional)
  4. 4. Low on oil (occasional)
  5. 5. Pinched hose (occasional)
  6. 6. Defective mini-valve (occasional)
  7. 7. Pressure relief valve not set properly (occasional)
  8. 8. Defective solenoid or wiring (occasional)
  9. 9. Defective relay box or pendant control (occasional)
  10. 10. Worn ball joint or retainer nut (occasional)

Brakes will not set properly patient safety

Brake cylinders fail to lock and hold the surgical table in position

Ranked causes

  1. 1. Emergency brake release valve open or defective (common)
  2. 2. Spool valve not centered (occasional)
  3. 3. Defective check valve (occasional)
  4. 4. Low on oil (common)
  5. 5. Pressure relief valve not set properly (occasional)
  6. 6. Pinched hose (occasional)
  7. 7. Defective mini-valve (occasional)
  8. 8. Defective relay box or pendant control (occasional)
  9. 9. Loose retaining hardware (occasional)

Lateral tilt function moves improperly patient safety

Lateral tilt slow, jerky, or unresponsive; table does not tilt smoothly left or right

Ranked causes

  1. 1. Incorrect speed adjustment (common)
  2. 2. Spool valve not centered (occasional)
  3. 3. Defective check valves (occasional)
  4. 4. Low on oil (occasional)
  5. 5. Pinched hose (occasional)
  6. 6. Defective mini-valve (occasional)
  7. 7. Pressure relief valve not set properly (occasional)
  8. 8. Defective solenoid (occasional)
  9. 9. Defective relay box or pendant control (occasional)

Table will not elevate properly patient safety

Elevation function insufficient or non-responsive; table cannot raise or raises slowly

Ranked causes

  1. 1. Pressure relief valve not set properly (common)
  2. 2. Low on hydraulic oil (common)
  3. 3. Spool valve not centered (occasional)
  4. 4. Defective pump (occasional)
  5. 5. Defective mini-valve (occasional)
  6. 6. Defective solenoid or wiring (occasional)
  7. 7. Defective relay box or pendant control (occasional)
  8. 8. Leaking cylinder hose (occasional)
  9. 9. Uneven weight distribution (rare)

Brakes will not retract properly caution

Brake cylinders do not fully retract when brake unlock is activated

Ranked causes

  1. 1. Incorrect speed adjustment (occasional)
  2. 2. Defective check valve (occasional)
  3. 3. Spool valve not centered (occasional)
  4. 4. Defective mini-valve (occasional)
  5. 5. Pinched hose (occasional)
  6. 6. Defective solenoid or wiring (occasional)
  7. 7. Defective relay box or pendant control (occasional)
  8. 8. Defective brake cylinder (occasional)

Table will not descend properly patient safety

Descent function insufficient or non-responsive; table cannot lower or lowers slowly

Ranked causes

  1. 1. Incorrect speed adjustment (common)
  2. 2. Defective check valve (common)
  3. 3. Spool valve not centered (occasional)
  4. 4. Galled slider assembly (occasional)
  5. 5. Defective solenoid or wiring (occasional)
  6. 6. Defective relay box or pendant control (occasional)
  7. 7. Uneven weight distribution (rare)

Kidney lift chatters or loses position caution

Kidney lift cylinders chatter during operation or fail to maintain position

Ranked causes

  1. 1. Defective or dirty check valve (common)
  2. 2. Oil leakage in circuit (common)
  3. 3. Air inside cylinder (occasional)
  4. 4. Pinched hose (occasional)
  5. 5. Low on oil (common)
  6. 6. Lift rods binding (occasional)

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

Back section function chatters or loses position patient safety

Back section unstable; function moves erratically or loses position when locked

Ranked causes

  1. 1. Defective or dirty check valves (common)
  2. 2. Oil leakage in circuit (common)
  3. 3. Air inside cylinder (occasional)
  4. 4. Pinched hose (occasional)
  5. 5. Low on oil (occasional)

Back section or trendelenburg flex function chatters or loses position patient safety

Flex function unstable; back section and trendelenburg move erratically or lose position

Ranked causes

  1. 1. Defective or dirty check valves (common)
  2. 2. Oil leakage in circuit (common)
  3. 3. Air inside cylinder (occasional)
  4. 4. Pinched hose (occasional)
  5. 5. Low on oil (occasional)

Lateral tilt function chatters or loses position patient safety

Lateral tilt unstable; function moves erratically or loses position when locked

Ranked causes

  1. 1. Defective or dirty check valves (common)
  2. 2. Oil leakage in circuit (common)
  3. 3. Air inside cylinder (occasional)
  4. 4. Pinched hose (occasional)
  5. 5. Low on oil (occasional)

Leg function chatters or loses position patient safety

Leg section unstable; function moves erratically or loses position when locked

Ranked causes

  1. 1. Defective or dirty check valves (common)
  2. 2. Oil leakage in circuit (common)
  3. 3. Air inside cylinder (occasional)
  4. 4. Pinched hose (occasional)
  5. 5. Low on oil (occasional)

Slide function chatters or loses position patient safety

Slide motion unstable; function moves erratically or loses position when locked

Ranked causes

  1. 1. Defective or dirty check valve (common)
  2. 2. Oil leakage in circuit (common)
  3. 3. Air inside cylinder (occasional)
  4. 4. Pinched hose (occasional)
  5. 5. Low on oil (occasional)

Trendelenburg function chatters or loses position patient safety

Trendelenburg position unstable; function moves erratically or loses position when locked

Ranked causes

  1. 1. Defective or dirty check valve (common)
  2. 2. Oil leakage in circuit (common)
  3. 3. Air inside cylinder (occasional)
  4. 4. Pinched hose (occasional)
  5. 5. Low on oil (occasional)

Brakes will not stay locked patient safety

Brakes release or lose pressure after being set, allowing table to drift

Ranked causes

  1. 1. Emergency brake release valve open or defective (common)
  2. 2. Defective or dirty check valve (common)
  3. 3. Oil leakage in circuit (common)
  4. 4. Leaking O-ring inside cylinder (occasional)

Table does not respond to control inputs

One or all control functions fail to operate; table may not move in any direction

Ranked causes

  1. 1. Motor/Pump Assembly defective (unknown)
  2. 2. Main Switch Circuit and Wiring fault (unknown)
  3. 3. Pendant control defective (unknown)
  4. 4. Relay Box defective (unknown)
First check

Switch operating mode from AC120V to BATTERY

Test point
Main power mode selector
Expected
Function operates in alternate mode

2 more checks with pass and fail actions are in ServiceForge. Connect ServiceForge to your AI

Table loses elevation position patient safety

Table descends or sinks after being elevated and locked; cannot maintain set height

Ranked causes

  1. 1. Defective check valve (common)
  2. 2. Leaking mini-valve (common)
  3. 3. Loose fittings, joints, or hoses (occasional)
  4. 4. Leaking O-ring inside cylinder (occasional)

Casters dirty or not rotating freely caution

Casters rough or sticky when rotated; debris and old grease present; table positioning difficult

Ranked causes

  1. 1. Debris and old grease accumulation in casters (common)
  2. 2. Casters not lubricated or worn bearing surfaces (occasional)
  3. 3. Casters worn or defective (occasional)
First check

Inspect each caster for debris and old grease

Test point
Caster assembly
Expected
Clean casters with no debris or old grease

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

Main wire harness continuity broken

Wiring between major components (battery, relay box, pump, solenoids) has open circuit or bad connection

Ranked causes

  1. 1. Battery circuit breaker (15 amp) open or in line fault between CN4 pin 1 and battery (+) (common)
  2. 2. Open or broken wire between CN4 and HN4 connectors (pump power) (occasional)
  3. 3. Open or broken wire between CN4 and HN3 (capacitor/rectifier unit) connectors (occasional)
First check

Continuity from CN4 pin 1 to battery (+) connector

Test point
CN4 pin 1(RED) and battery positive terminal
Expected
continuity (0 ohms)
Tools
Ohmmeter

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

Motor/pump assembly not producing hydraulic pressure high voltage

Hydraulic pump not delivering oil flow when power applied, affecting all table functions

Ranked causes

  1. 1. Motor or wiring defective; motor resistance out of specification (common)
  2. 2. No input power to motor due to relay box or wiring fault (common)
  3. 3. Thermal protector tripped after continuous operation (occasional)
First check

Motor input voltage (AC120V mode, all connectors connected)

Test point
HN4 pins 1(+) RED and 2(-) BLUE
Expected
approximately 24-28 volts when function button activated V, 24-28 V
Tools
DC voltmeter

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

Return-to-level function not working patient safety

LEVEL button on pendant control does not automatically level major table functions (lateral tilt, Trendelenburg, back section, leg section)

Ranked causes

  1. 1. Micro-switch circuit disconnected or faulty at CN10 connector (common)
  2. 2. Defective micro-switch (NS-1 through NS-7) (occasional)
  3. 3. Riser cord or wiring continuity broken between CN10 and terminal strips TM1/TM2 (occasional)
First check

Verify table functions work without CN10 connected

Test point
CN10 connector at relay box
Expected
All functions operate properly using Pendant Control

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

Auxiliary switches not functioning

Switch controls for table movements (up, down, tilt, trend, back, kidney, leg, brake) not responding to activation

Ranked causes

  1. 1. Wires loose or bad connection at CN2 connector or switch circuit board (common)
  2. 2. Individual switch defective (occasional)
First check

Continuity at CN2 connector pins

Test point
CN2 pins (pin 1A common)
Expected
0 ohms
Tools
Ohmmeter

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

No AC120V operation available high voltage

Table functions fail when operating in AC120V mode

Ranked causes

  1. 1. Power cord not connected or faulty (common)
  2. 2. Transformer output voltage incorrect (occasional)
First check

Confirm 120VAC input at main switch output

Test point
Connector HN1 pins 1 and 2
Expected
120 VAC
Tools
AC voltmeter

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

No BATTERY mode operation available

Table functions fail when operating in BATTERY mode

Ranked causes

  1. 1. Battery voltage below minimum (common)
  2. 2. Battery voltage drops below 11VDC under load (occasional)
First check

Test individual battery voltage at rest

Test point
Battery 1 and Battery 2 terminals
Expected
12 VDC ± 1 V each, ±1 V
Tools
DC voltmeter

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

Rectifier or charging system fault high voltage

DC voltage outputs from Capacitor/Rectifier Unit incorrect

Ranked causes

  1. 1. Capacitor/Rectifier Unit defective (unknown)
  2. 2. Transformer defective (unknown)
First check

Test DC voltage output pin 1 (purple) to ground

Test point
Connector HN3 pins 1 (purple) and 2 (black, ground)
Expected
30 VDC
Tools
DC voltmeter

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

Side rails loose or gravity stops restricted patient safety

Retaining hardware loose on side rail sections or gravity stops do not move freely

Ranked causes

  1. 1. Retaining hardware loose or corroded (common)
  2. 2. Gravity stops stuck or damaged (occasional)
First check

Inspect side rail sections for loose retaining hardware

Test point
Side rail fasteners
Expected
All hardware tight and secure

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

Single control function inoperative

One directional or function button does not respond

Ranked causes

  1. 1. Solenoid for that function defective (common)
  2. 2. Auxiliary switch or relay for function faulty (occasional)
First check

Test function with auxiliary switches

Test point
Auxiliary switch for the specific function
Expected
Function operates when auxiliary switch is used

Solenoid coil defective

Solenoid not energizing or holding, preventing hydraulic valve spool movement in one or more directions

Ranked causes

  1. 1. Solenoid coil resistance out of specification or open circuit (common)
  2. 2. Thermal fuse inside solenoid blown from continuous operation (occasional)
First check

Solenoid coil resistance

Test point
Between both pins at solenoid connector
Expected
approximately 16 ohms at room temperature, approximately 16 ohms
Tools
Ohmmeter R x 1 scale

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

Top slide function not moving toward foot end patient safety

Slide mechanism remains stationary or will not move toward foot end when control is activated

Ranked causes

  1. 1. Back section below horizontal (CS-1 inhibit switch active) (common)
  2. 2. CS-1 Back-Down Inhibit switch malfunction (occasional)
First check

Check back section position

Test point
Back section visual position or angle indicator
Expected
Back section at or above horizontal

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

Top slide function not moving toward head end patient safety

Slide mechanism remains stationary or will not move toward head end when control is activated

Ranked causes

  1. 1. Leg section lowered more than 45° below horizontal (CS-2 inhibit active) (common)
  2. 2. CS-2 Leg-Down 45° Inhibit switch malfunction (occasional)
First check

Check leg section position

Test point
Leg section visual position or angle indicator
Expected
Leg section within 45° below horizontal

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

Trendelenburg ball joint has visible play patient safety

Movement observed when table top is slid to extremities and load applied; no visible play is permitted

Ranked causes

  1. 1. Ball joint collar or locking allen bolt loose (common)
  2. 2. Ball socket wear or metal particulate damage (occasional)
First check

Slide table top to each extremity and apply load

Test point
Trendelenburg ball joint
Expected
No visible play or movement in joint

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

Back section cannot be lowered below horizontal when slide is toward foot patient safety

Back section control non-responsive or locked when table top is slid toward foot end

Ranked causes

  1. 1. CS-1 Back-Down Inhibit switch functioning correctly (protective inhibit) (common)
First check

Check slide position

Test point
Top slide position (center/head/foot)
Expected
Slide at center or toward head end

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

Back section cannot be raised more than 45° when kidney lift is up patient safety

Back section movement is restricted; stops at 45° above horizontal when kidney lift is in raised position

Ranked causes

  1. 1. CS-3 Back-Up Inhibit switch functioning correctly (protective inhibit active) (common)
First check

Verify kidney lift position

Test point
Kidney lift position indicator or visual inspection
Expected
Kidney lift fully down

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

Calibration: CS-5 kidney lift inhibit switch verification patient safety

Verify CS-5 kidney lift inhibit switch operation at different back section angles to ensure kidney lift is properly blocked when back section exceeds 45 degrees.

Ranked causes

  1. 1. Switch contact or circuit malfunction (unknown)
First check

Measure switch continuity with back section less than 45 degrees

Test point
CN10 pins 12 & 24
Expected
Infinity
Tools
DMM

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

Calibration: Micro-switch adjustment for level return

Table does not properly return to level, or improper readings obtained during test. Requires switch bracket adjustment.

Ranked causes

  1. 1. Micro-switch bracket misalignment (common)
First check

Level table top using pendant control

Test point
TRENDELENBURG and LATERAL-TILT function buttons
Expected
Table top level

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

Charging Indicator LEDs not illuminating

Charging indicator does not show battery charge level

Ranked causes

  1. 1. No signal from relay box to charging indicator (unknown)
First check

Test charging indicator signal from relay box

Test point
Relay box CN3 pin 11 (common) to pin 1 (lowest charge)
Expected
approximately 1.8 VDC
Tools
DC voltmeter

Head section flexing throughout range of travel patient safety

Head section exhibits flexing during articulation; not rigid throughout travel range

Ranked causes

  1. 1. Bearing block misalignment or loose fasteners (common)
First check

Place head section in level position and remove top

Test point
Head section
Expected
Head section level, top removed

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

Kidney lift cannot be raised when back section is above 45° patient safety

Kidney lift remains stationary; audible alarm sounds when attempting to raise kidney lift while back section is elevated above horizontal

Ranked causes

  1. 1. CS-3 Back-Up Inhibit switch functioning correctly (common)
First check

Test back section position

Test point
Back section angle indicator or visual position
Expected
Back section at or below 45° above horizontal

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

Kidney lift cylinder piston extension incorrect caution

Kidney lift piston-to-cylinder end distance not at specification when fully down; prevents proper operation

Ranked causes

  1. 1. Kidney lift cylinder removed and not reset to proper extension (common)
First check

Measure kidney lift piston extension with kidney lift all the way down

Test point
Kidney lift cylinder, head end
Expected
82 mm
Tools
Ruler or measuring tape

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

Kidney lift cylinders misaligned at end of stroke caution

One kidney lift cylinder reaches full down or up position before the other

Ranked causes

  1. 1. Bypass valve requires adjustment (common)

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

Lateral tilt thrust bearing loose or improper torque caution

Lateral tilt M8 x 20 allen bolt not properly secured; only for serial numbers before 3501B-81-357

Ranked causes

  1. 1. M8 x 20 lateral tilt thrust bearing allen bolt loose or improper torque (common)
First check

Remove M8 x 20 lateral tilt thrust bearing allen bolt

Test point
Lateral tilt thrust bearing bolt
Expected
Bolt removed without damage
Tools
6mm allen wrench

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

Leg section cannot be lowered more than 45° when slide is toward head patient safety

Leg section control non-responsive or locked at 45° when table top is slid toward head end

Ranked causes

  1. 1. CS-2 Leg-Down 45° Inhibit switch functioning correctly (protective inhibit) (common)
First check

Check slide position

Test point
Top slide position (center/head/foot)
Expected
Slide at center or toward foot end

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

Leg section twists or flexes at full extension patient safety

Leg section shows twisting or flexing as it approaches stalled position; both sides do not stop moving at same time

Ranked causes

  1. 1. One cylinder not reaching fully extended position simultaneously (common)
First check

Position leg section all the way up

Test point
Leg section
Expected
Both sides stop moving at same time with no twisting or flexing

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

No output voltage to pump motor high voltage

Pump/motor relay not supplying 24V power when function buttons activated

Ranked causes

  1. 1. Broken continuity in HN4 to CN4 wiring (red or black wires) (common)
First check

Output voltage to pump (AC120V mode, all connectors connected)

Test point
HN4 pins 1(+) RED and 2(-) BLUE
Expected
approximately 24-28 volts when function button activated V, 24-28 V
Tools
DC voltmeter

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

No output voltage to solenoids high voltage

Solenoid energizing circuit not supplying 24V to hydraulic valve actuators when function buttons activated

Ranked causes

  1. 1. Relay box defective (common)
First check

Solenoid output voltage at CN1A

Test point
CN1A connector pins (activate each function button)
Expected
24 volts V
Tools
DC voltmeter

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

Relay box input power absent or low high voltage

Power supply not delivering correct voltage to relay box circuits

Ranked causes

  1. 1. Problem in input wiring, connectors or power supply components (common)
First check

Relay box input power voltage (BATTERY mode)

Test point
CN4 pins 1(+) BLUE and 2(-) BLUE
Expected
approximately 24-28 volts V, 24-28 V
Tools
DC voltmeter

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

Slide cylinder piston extension incorrect caution

Slide piston-to-cylinder end distance not at specification; prevents proper slide range of motion

Ranked causes

  1. 1. Slide cylinder removed and not reset to proper extension (common)
First check

Measure slide piston extension with table top centered

Test point
Slide cylinder, head end
Expected
82 mm
Tools
Ruler or measuring tape

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

Slide roller binding or uneven contact caution

Rollers not contacting slide bars evenly; table top moves with up or down movement or binds during slide

Ranked causes

  1. 1. Slide roller adjustment eccentric cam out of position (common)
First check

Remove seat section top, hose cover, and lateral tilt frame covers

Test point
Slide roller adjustment area
Expected
Access to top rollers obtained

4 more checks with pass and fail actions, 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.