Toshiba DK 16, DK8 Defective Apparatus Returns, Fault Identification and Elimination Procedures

FAULT FINDING

SECTION 100-816-500

MARCH 1993

3.06The following precautions must be observed when handling PCBs:

DO NOT:

•Drop a PCB.

•Stack one PCB on top of another.

•Handle a PCB without discharging any static electricity from your person by touching the grounded cabinet.

•Touch PCB contacts with your fingers.

Important!

If the fault is not cleared by substituting a PCB, the original PCB must be reinstalled in the KSU before trying another PCB.

4 DEFECTIVE APPARATUS RETURNS

4.01When a defective system apparatus is shipped for repair, the apparatus must be packed in a suitable container (the original box is highly recommended), as follows:

a)Anti-static containers for all other PCBs and Feature cartridge.

b)Plastic bags for digital or electronic tele- phones, KSU, etc.

4.02NEVER WRITE ON THE APPARATUS ITSELF! Describe the nature of the defect on an information tag. Attach the tag to the front of the unit with string (not wire) so the tag can remain attached during the testing and repair process. Return tags are available from Toshiba America Information Systems, Inc., TSD Division.

5FAULT IDENTIFICATION AND ELIMINATION PROCEDURES

5.01The DK8 or DK16, KSU common control circuits or DK16 KFCU may contain a “soft” fault due to an extremely high level of static electricity. If it is found defective during the fault finding procedures, attempt to clear a soft fault prior to returning the KSU or KFCU for repair. The correct procedure for this is to perform the initialization procedure, and then re-program the system as necessary to test for the fault. If the fault returns after these procedures are performed, tag the defective KSU or KFCU and return it for repair.

6 DK8 HARDWARE FAULT ISOLATION

6.01If a DK8 hardware fault is suspected, check the hardware using the following procedure:

1)Make sure the BATT jumper plug (SW1 on the KSU motherboard) is in the ON position to save the system’s customer data base.

2)Unplug HPFB battery cable from BATT con- nector on QPSU8 Power Supply (see Figure 2).

3)Remove all piggy-back PCBs from the DK8 motherboard one at a time. Retest to check if the problem is cleared each time a PCB is removed. If it is found that a particular PCB is causing the problem, replace that PCB and retest (piggy-back PCBs include QSTU, QCDU, QRCU, QCNU, and QSMU).

4)Test power supply as follows (refer to Figure 2):

a)Plug the AC power cable into an outlet.

•The “AC” LED on the power supply should light green.

b)Turn the power supply switch to the ON position.

•The “DC” LED on the power supply should light green.

c)Using the voltmeter, measure the volt- ages referenced to frame ground (FG) at the power supply connector CN3 pins (test points) and pin 42 of IC5 located on the motherboard (Figure 2). The volt- ages should fall within the ranges below. If the voltages do not fall within the range, unplug the DC power pins from power supply connector CN3 and mea- sure +24V again at the same location; if the voltages remain unacceptable, re- place the power supply (see Section 100-816-204).

•J19 Green Wires: 0V

•J19 Yellow Wires: +24V

§Range: +26.3V ~ +27.8V

•IC5, Pin 42, +5V

§Range: +4.5V ~ +5.5V

d)If the +24V tests within range but +5V is not with-in specification, the KSU must be replaced.

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