Oral surgery tables

Midmark 318: troubleshooting and error codes

The ServiceForge knowledge base holds 18 documented symptoms for the Midmark 318, with 45 ranked causes, 20 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

Motor pump does not run but solenoid energizes

Solenoid click is audible when foot pedal is depressed but motor pump does not run

Ranked causes

1. Capacitor blown (common)
2. Motor thermal overload switch activated (occasional)
3. Motor pump burned out (occasional)
4. Wire connections loose to motor pump (occasional)

First check

Listen for solenoid click when pedal depressed

Test point: Solenoid audible feedback
Expected: Audible click sound

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

Table moves slowly or not at all for heavy patient

Table functions normally for light patients but fails or moves slowly for heavier loads

Ranked causes

1. Hydraulic system low on mineral oil (common)
2. Both up and down relief valves malfunctioning (rare)
3. Up relief valve malfunctioning (up functions only) (occasional)
4. Down relief valve malfunctioning (down functions only) (occasional)

First check

Check oil level in reservoir

Test point: Oil reservoir
Expected: Oil level at proper mark

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

Table up functions do not work but down functions do

TABLE UP, BACK UP, TILT UP, and FOOT UP pedals produce no movement

Ranked causes

1. Anti-cavitation solenoid valve malfunctioning (occasional)
2. Wire connections loose to solenoid valve (occasional)
3. Up function shuttle valve malfunctioning (rare)
4. Motor pump defective (rare)

First check

Check solenoid valve magnetism

Test point: Anti-cavitation solenoid valve bottom
Expected: Slight magnetism present

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

BACK UP and BACK DOWN functions do not work

Both back movement directions fail while all other functions work

Ranked causes

1. Back cylinder solenoid valve malfunctioning (occasional)
2. Wire from foot switch terminal 3 broken or disconnected (occasional)
3. Wire to back cylinder solenoid valve broken or disconnected (occasional)

First check

Listen for solenoid energize click

Test point: Back cylinder solenoid valve
Expected: Audible click when pedal depressed

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

TABLE UP and TABLE DOWN functions do not work

Both table movement directions fail while all other functions work

Ranked causes

1. Base cylinder solenoid valve malfunctioning (occasional)
2. Wire from foot switch terminal 3 broken or disconnected (occasional)
3. Wire to base cylinder solenoid valve broken or disconnected (occasional)

First check

Listen for solenoid energize click

Test point: Base cylinder solenoid valve
Expected: Audible click when pedal depressed

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

Table will not operate when any function is selected

Motor pump does not run and solenoid cannot be heard energizing when foot pedal is depressed

Ranked causes

1. Power cord not plugged in (common)
2. Facility circuit breaker is tripped (common)
3. Wire connections loose (occasional)

First check

Is power cord plugged in

Test point: Facility wall outlet

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

TILT UP and TILT DOWN functions do not work

Both tilt movement directions fail while all other functions work

Ranked causes

1. Tilt cylinder solenoid valve malfunctioning (occasional)
2. Wire from foot switch terminal 3 broken or disconnected (occasional)
3. Wire to tilt cylinder solenoid valve broken or disconnected (occasional)

First check

Listen for solenoid energize click

Test point: Tilt cylinder solenoid valve
Expected: Audible click when pedal depressed

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

Excessive sideways play of table top caution

Table top can be moved side to side or is unstable laterally

Ranked causes

1. Chain assemblies loose (common)
2. Base slide assembly worn or deformed (occasional)

First check

Check chain assembly tension

Test point: Chain assemblies

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

FOOT UP and FOOT DOWN functions do not work

Both foot movement directions fail while all other functions work

Ranked causes

1. Foot cylinder solenoid valve malfunctioning (occasional)
2. Wire from foot switch terminal 3 broken or disconnected (occasional)

First check

Listen for solenoid energize click

Test point: Foot cylinder solenoid valve
Expected: Audible click when pedal depressed

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

Motor pump hums but does not run

Motor pump hums when foot pedal is depressed but does not rotate

Ranked causes

1. Capacitor blown (common)
2. Motor pump locked up or burned out (occasional)

First check

Listen for motor humming sound

Test point: Motor pump area
Expected: Motor hums when pedal depressed

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

Motor pump runs but table top does not move

Foot pedal is depressed, motor pump runs but table fails to move

Ranked causes

1. Time delay relay malfunctioning (rare)
2. Hydraulic system low on mineral oil (common)

First check

Check hydraulic oil level

Test point: Reservoir sight glass or filler
Expected: Oil level within specified range

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

Single BACK function does not work

Either BACK UP or BACK DOWN pedal produces no movement while other direction and all other functions work

Ranked causes

1. Foot switch malfunctioning (common)
2. Wire connection to foot switch loose (occasional)

First check

Perform continuity check on foot switch

Test point: Suspect BACK foot switch
Tools: Multimeter

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

Single FOOT function does not work

Either FOOT UP or FOOT DOWN pedal produces no movement while other direction and all other functions work

Ranked causes

1. Foot switch malfunctioning (common)
2. Wire connection to foot switch loose (occasional)

First check

Perform continuity check on foot switch

Test point: Suspect FOOT foot switch
Tools: Multimeter

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

Single TABLE function does not work

Either TABLE UP or TABLE DOWN pedal produces no movement while other direction and all other functions work

Ranked causes

1. Foot switch malfunctioning (common)
2. Wire connection to foot switch loose (occasional)

First check

Perform continuity check on foot switch

Test point: Suspect TABLE foot switch
Tools: Multimeter

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

Single TILT function does not work

Either TILT UP or TILT DOWN pedal produces no movement while other direction and all other functions work

Ranked causes

1. Foot switch malfunctioning (common)
2. Wire connection to foot switch loose (occasional)

First check

Perform continuity check on foot switch

Test point: Suspect TILT foot switch
Tools: Multimeter

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

Table down functions do not work but up functions do

TABLE DOWN, BACK DOWN, TILT DOWN, and FOOT DOWN pedals produce no movement

Ranked causes

1. Down function shuttle valve malfunctioning (rare)
2. Motor pump defective (rare)

First check

Check check ball in shuttle valve

Test point: Down function shuttle valve or adjacent elbow
Expected: Check ball held in place by metal ring

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

Table or function drifts by itself

One or more functions move on their own when no pedal is depressed, though other functions work normally

Ranked causes

1. Cylinder solenoid valve stuck open or malfunctioning (common)
2. Foot switch malfunctioning holding solenoid open (occasional)

First check

Check voltage at foot switch terminal 3 in OFF position

Test point: Terminal 3 of suspect foot switch
Expected: No voltage present
Tools: Multimeter

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

Back section can be lifted or tilt drifts by itself

Back section moves manually or tilt function drifts without pedal input

Ranked causes

1. Anti-cavitation solenoid valve malfunctioning (common)

First check

Try to lift back section by hand

Test point: Back section of table top
Expected: Back section should not lift without up pedal

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.