Technics SX-PX552, Service Manual

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No. PCB TEST MODE Procedure
1 MAIN RAM (IC8, 9), ROM (IC6)
check 1. Connect the CHECKING DEVICE to CN9 on the MAIN P.C.B.,
and turn on the CHECKING DEVICE switch.
2. Turn on the power switch.
When the power switch is turned on, the LED of the CHECKING DEVICE flashes 8 times.
first 4 flashes are for the RAM check , and the latter 4 flashes are for the ROM check.
order of the LED flashes correspond to the respective IC numbers as shown below.
defective, the corresponding flash time is longer.
2 CPL CPU (IC1) check 1. Connect the CHECKING DEVICE to CN9 on the MAIN P.C.B.
Checking Device switch should be off).
2. Press and hold the two D keys shown below, and then
the power switch.
When the power switch is turned on, the LED of the CHECKING DEVICE flashes 4 times.
order of the LED flashes corresponds to the CPU (IC) on the respective P.C.B.s as shown
below. If an IC is defective, the corresponding flash time is longer.
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