Replacing Pcbs; Replacing The Main Processor Board - GE P642 Technical Manual

P64x
Caution:
Before removing the front panel, you should be familiar with the contents of the Safety
Information section of this guide or the Safety Guide SFTY/4LM, as well as the ratings
on the equipment's rating label.
To remove the front panel:
1. Open the top and bottom access covers. You must open the hinged access covers by more than 90° before
they can be removed.
2. If fitted, remove the transparent secondary front cover.
3. Apply outward pressure to the middle of the access covers to bow them and disengage the hinge lug, so the
access cover can be removed. The screws that fasten the front panel to the case are now accessible.
4. Undo and remove the screws. The 40TE case has four cross-head screws fastening the front panel to the
case, one in each corner, in recessed holes. The 60TE/80TE cases have an additional two screws, one
midway along each of the top and bottom edges of the front plate.
5. When the screws have been removed, pull the complete front panel forward to separate it from the metal
case. The front panel is connected to the rest of the circuitry by a 64-way ribbon cable.
6. The ribbon cable is fastened to the front panel using an IDC connector; a socket on the cable and a plug
with locking latches on the front panel. Gently push the two locking latches outwards which eject the
connector socket slightly. Remove the socket from the plug to disconnect the front panel.
Caution:
Do not remove the screws with the larger diameter heads which are accessible when
the access covers are fitted and open. These screws hold the relay in its mounting
(panel or cubicle).
Caution:
The internal circuitry is now exposed and is not protected against electrostatic
discharge and dust ingress. Therefore ESD precautions and clean working conditions
must be maintained at all times.
2.5

REPLACING PCBS

1. To replace any of the PCBs, first remove the front panel.
2. Once the front panel has been removed, the PCBs are accessible. The numbers above the case outline
identify the guide slot reference for each printed circuit board. Each printed circuit board has a label stating
the corresponding guide slot number to ensure correct relocation after removal. To serve as a reminder of
the slot numbering there is a label on the rear of the front panel metallic screen.
3. Remove the 64-way ribbon cable from the PCB that needs replacing
4. Remove the PCB in accordance with the board-specific instructions detailed later in this section.
Note:
To ensure compatibility, always replace a faulty PCB with one of an identical part number.
2.5.1

REPLACING THE MAIN PROCESSOR BOARD

The main processor board is situated in the front panel. This board contains application-specific settings in its non-
volatile memory. You may wish to take a backup copy of these settings. This could save time in the re-
commissioning process.
P64x-TM-EN-1.3
Chapter 20 - Maintenance and Troubleshooting
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