5-9
• Short-circuit on solid state power relay. Check 1SSR.
Inaccurate Temperature Control
Typical Causes
• Control thermocouple not making good contact with target plate.
• PID parameters improperly adjusted. See “Manual Tuning Procedure” on
page 3.5 of Series F4 User’s Manual.
5.2.6 Lid Lock Assist Failure
The lid lock assist employs two switches that are used to detect the lid handle
position and to signal the control system at appropriate times to initiate either a
vacuum, exhaust, or a backfill sequence. Referring to pictorial drawing “Lid
Assembly,” locate item 24. The up switch is located to the right of the down
switch, when either of the switches fails the following symptoms will be
observed:
Up Position Switch Failure
• Switch fails in the open position: System will not perform a backfill
sequence after pressing the lid switch.
• Switch fails in the closed position: System performs a continuous
backfill sequence after pressing the lid switch.
Down Position Switch Failure
• Switch fails in the open position: System will not initiate vacuum after
pressing the lid switch.
• Switch fails in the closed position: System will not release vacuum after
pressing the lid switch.
5.3 Repairs and Adjustments
5.3.1 Heating Element Replacement
• Referring to the pictorial drawing “Chamber Assembly” in Section 5.4,
remove 4 flat head slotted screws, item 10, and the radiation shield, item
2, from the chamber. Remove two insulators, two hex nuts, two washers,
and the old heating element, items 37, 11, 12, and 3 from the chamber. If
the chamber needs cleaning, remove the insulator rods, element supports,
insulator sleeves, and the lower radiation shield, items 4, 6, 21, and 18.
Clean the chamber as required and reinstall the parts in the reverse order
that they were removed. Be very careful with the new element and keep
it supported while lowering it over the electrodes. When tightening the
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