Thermo Electron 8600 Series, Troubleshooting Service Manual

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2.6 Symptom: No Door Access
Order Possible Cause Verification Action
1
Door locked. Check to ensure door is not locked. Unlock door.
2
Vacuum relief assembly is frozen over.
Visually inspect vacuum relief port for any
restrictions. Clean as necessary. Follow routine maintenance
instructions in user’s manual to periodically clean
the port.
Check voltage at J7 on the display board for +14V
+ 0.5?
YES (+14V): unplug heater harness from PCB and
measure resistance across heater leads. Heater
resistance should be between 9 and 30 Ohms.
If not between 9 and 30 Ohms, replace VRP
assembly.
3
Release 3 unit: Vacuum relief not
functioning.
Release 3 units(built after 6/2005 have
vacuum relief port in door.
NO: Check and reseat connections on heater harness.
Measure DC voltage at the switching power supply.
On the 6 pin connector, measure between pins 1 and
6 (+14V + 0.5V) Check and reseat connectors between switching
power supply and high voltage board. Also check
and reseat connections between high voltage
board and micro board.
Verify unit is colder than –50°C. Cabinet temperature must be colder than –50°C to
activate vacuum relief heater.
90-130VAC at heater?
YES : Ohm out heater. Heater to be 1037-1210 Ohms
Replace heater if required.
Release 1 unit: Vacuum relief not
functioning.
Release 2 units built between May 2003
and June 2005 do not use a heated vacuum
relief assembly.
NO : Check connections Re-seat connection(s). If problem still exists,
continue troubleshooting.
Blown fuse Check fuse. Ohm out fuse, replace fuse as required.
Micro board Check voltage between U16-13 and J11-1 on micro
board. If voltage is greater than 10VDC, replace micro
board.
High voltage board. Check DC voltage across D15 on high voltage. If voltage is less than 10VDC, replace high
voltage board.