Midmark M7 Troubleshooting Guide



 

Midmark M7 Troubleshooting Guide

Problem Symptom Probable Cause Check Correction
Unit Seems Powerless Pilot light does not illuminate when timer is set and unit does not start to heat up. Power cord is not plugged in to wall outlet. Check to see if power cord is plugged in. Plug power cord into facility wall outlet.


Facility circuit breaker providing power to unit is tripped. Check to see if facility circuit breaker is tripped. One way of checking this is to plug a lamp into wall outlet that unit was plugged into. If circuit breaker is tripped, determine what caused circuit breaker to trip, correct the problem, and then reset/replace circuit breaker.


Manual reset overheat thermostat is tripped. If the unit is hot, allow the unit to cool for 15 to 20 minutes. Press the RESET button on the front panel. Now, the PILOT light should illuminate when the TIMER knob is set. If necessary, add distilled water to condensing tank; then press the RESET button on the front panel.


Auto-reset overheat thermostat is tripped (Applies only to units with Serial Numbers CS5297 and RB14565 Thru Present). If the unit is hot, allow the unit to cool for 15 to 20 minutes. Now, the PILOT light should illuminate when the TIMER knob is set. Wait 15 to 20 minutes to allow thermostat to reset itself. Also, replace manual reset overheat thermostat. Refer to para 4.8.


Manual reset or auto-reset overheat thermostat is malfunctioning - stuck open (Auto-reset overheat thermostat is only on units with Serial Numbers CS5297 and RB14565 Thru Present). Perform continuity check on N.C. overheat thermostat (cool = closed). If open, replace overheat thermostat. Refer to para 4.8.


Timer assembly is malfunctioning. Replace suspect timer assembly with known working timer assembly. Replace timer assembly. Refer to para 4.3 or 4.4.


Temperature regulator relay is malfunctioning - stuck open. Perform continuity check on temperature regulator relay. Replace temperature regulator relay. Refer to para 4.9.


Wiring connections loose. Check all wiring connections Clean any dirty connections. Tighten any loose connections. Replace any damaged connections.
Unit does not complete sterilization cycle properly. PILOT light does illuminate but chamber does not reach required temperature / pressure during sterilization cycle. Flexible shaft assembly is malfunctioning. Check flexible shaft assembly for wear or damage Replace flexible shaft assembly. Refer to para 4.9.


Temperature regulator relay is out of adjustment. Check adjustment of temperature regulator relay. Adjust temperature regulator relay. Refer to para 4.10.


Temperature regulator relay is malfunctioning. Check if temperature regulator relay is stuck open or contacts not touching properly. Replace temperature regulator relay. Refer to para 4.9.


Heating element is malfunctioning. Check resistance of heating element (in ohms):
100 V, 50 Hz-8.08 to 8.94
115 V, 60 Hz-11.31 to 12.5
230 V, 50 Hz-45.65 to 50.45
If heating element resistance is not within range, replace heating element. Refer to para 4.7.


Bellows assembly is closing prematurely or stuck in open position. Replace suspect bellows assembly with known working bellows assembly. Replace bellows assembly. Refer to para 4.14, 4.15, or 4.16.


Pressure relief valve is malfunctioning - stuck open. Run cycle and observe pressure relief valve; it should not dump pressure until temperature gauge reads 275 degrees F (135 degrees C) +/- 2 degrees Replace pressure relief valve. Refer to para 4.13.


Diaphragm cup is malfunctioning. Replace suspect diaphragm cup with known working diaphragm cup. Replace diaphragm cup. Refer to para 4.11.


Fill / vent valve is malfunctioning - stuck open or leaking past o-rings. Check fill / vent valve for dirt and o-rings for wear or damage. Clean or replace fill / vent valve. Refer to para 4.17.


Door gasket and / or door assembly is leaking. Run cycle and observe for leaks around edges of door assembly. Replace door gasket. Refer to para 4.19. Replace door assembly if necessary. Refer to para 4.18.

Temperature reaches 210 - 212 degrees F (98.8 - 100 degrees C) during cycle and stays there. Bellows assembly is stuck in open position. Replace suspect bellows assembly with known working bellows assembly. Replace bellows assembly. Refer to para 4.14, 4.15, or 4.16..

Time set on timer assembly does not expire. Timer motor is malfunctioning. Replace suspect timer assembly with known working timer assembly. Replace timer assembly. Refer to para 4.3 or 4.4.


Manual reset overheat thermostat is tripped. If the unit is hot, allow the unit to cool for 15 to 20 minutes. Press the RESET button on the front panel. Now, the PILOT light should illuminate when the TIMER knob is set. If necessary, add distilled water to condensing tank; then press the RESET button on the front panel


Auto-reset overheat thermostat is tripped (Applies only to units with Serial Numbers CS5297 and RB14565 Thru Present). If the unit is hot, allow the unit to cool for 15 to 20 minutes. Now, the PILOT light should illuminate when the TIMER knob is set. Wait 15 to 20 minutes to allow thermostat to reset itself. Also, replace manual reset overheat thermostat. Refer to para 4.8.


Manual reset or auto-reset overheat thermostat is malfunctioning - stuck open (Auto-reset overheat thermostat is only on units with Serial Numbers CS5297 and RB14565 Thru Present). Perform continuity check on N.C. overheat thermostat (cool = closed). If open, replace overheat thermostat. Refer to para 4.8.


Diaphragm cup is malfunctioning - is failing to open contacts of temperature regulator relay when maximum temperature (270 degrees F [132 degrees C]) is reached resulting in overheating. Replace suspect diaphragm cup with known working diaphragm cup. Replace diaphragm cup. Refer to para 4.11.

Chamber does not vent at completion of cycle when the FILL / VENT lever is depressed. Fill / vent valve is clogged with foreign matter Check fill / vent valve for foreign matter. Clean or replace fill / vent valve. Refer to para 4.17.


Tubing is clogged. Check tubing for foreign matter. Clean out tubing.

Sterility Indicators show sterilization standards were not met Improper loading of unit. Check operator's manual for recommended loading procedures Load unit properly and repeat cycle.


Temperature regulator relay is out of adjustment. Check adjustment of temperature regulator relay using a lag thermometer - TEMPERATURE gauge on front panel may be giving inaccurate reading. Adjust temperature regulator relay. Refer to para 4.10.


Bellows assembly is stuck in open position. Replace suspect bellows assembly with known working bellows assembly. Replace bellows assembly. Refer to para 4.14, 4.15, or 4.16.

Timer does not buzz at end of cycle. Timer buzzer is malfunctioning. Replace suspect timer buzzer with known working timer buzzer Replace timer buzzer. Refer to para 4.5.
FILL / VENT function does not work properly When FILL / VENT lever is depressed, water does not flow into chamber Fill / vent valve is clogged with foreign matter. Check fill / vent valve for foreign matter. Clean or replace fill / vent valve. Refer to para 4.17.


Fill / Vent valve is not adjusted to open and close properly. Check adjustment of Fill / Vent valve. Adjust closing bracket on fill vent valve. Refer to para 4.17.


Condensing tank is low on distilled or demineralized water. Check water level in condensing tank. Fill condensing tank with water up to FULL mark.


Tubing is clogged. Check condensing tank and tubing for foreign matter. Clean out condensing tank and tubing. Replace condensing tank if necessary. Refer to para 4.21. Replace tubing if necessary.

When FILL / VENT lever is released, water continues to enter the chamber. Fill / vent valve is clogged with foreign matter. Check fill / vent valve for dirt. Clean or replace fill / vent valve. Refer to para 4.17.


O-rings in Fill / Vent valve are worn or damaged. Check o-rings in Fill / Vent valve for wear or damage. Repair Fill / Vent Valve. Refer to para 4.17.


Fill / Vent valve is not adjusted to open and close properly. Check adjustment of Fill / Vent valve. Adjust closing bracket on fill vent valve. Refer to para 4.17.

When FILL / VENT lever is depressed, water does not vent from chamber Fill / vent valve is clogged with foreign matter. Check fill / vent valve for dirt. Clean or replace fill / vent valve. Refer to para 4.17.


Fill / Vent valve is not adjusted to open and close properly. Check adjustment of Fill / Vent valve. Adjust closing bracket on fill vent valve. Refer to para 4.17.


Tubing is clogged. Check condensing tank and tubing for foreign matter. Clean out condensing tank and tubing. Replace condensing tank if necessary. Refer to para 4.21. Replace tubing if necessary.
Non operational problems with sterilizer Sterilizer slides on counter top. Film or grease on counter top. Check for film or grease on counter top. Clean counter top.


Damaged "suction" foot Check if "suction" foot works. Replace damaged "suction" foot.

Water leaks around sterilizer. Loose fittings. Check all fittings for leaks. Remove fitting, coat threads of fitting with Teflon tape or sealant, and reinstall fitting.


Compression nut and/ or compression sleeve is loose or excessively deformed Check all compression nuts for leaks. Loosen compression nut. Replace compression sleeve if necessary.


Tubing is damaged. Check for holes, kinks, or other types of damage to tubing. Replace tubing.

Door handle is hard to operate Handle cam is dry. Check for lubricant on cam of door handle. Lubricate cam part of handle with high temperature grease.

Water leaks around door during cycle. Door gasket is worn or damaged. Check door gasket for wear or damage. Replace door gasket. Refer to para 4.19
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