Technics SX-KN1400 - About the Self-Diagnostic Function

ABOUT THE SELF-DIAGNOSTIC FUNCTION
This model has some self-diagnostic capabilities. There are two types of self-diagnostic functions: the “power on self-test” which runs
a test when the power is turned on and notifies the user if an error is detected, and the “service mode” which is used when servicing
the unit.
@ Power on self-test
This model runs the following self-diagnostic test when power is turned on. If an error is detected, a message is displayed on the
LCD to notify the user.
Communication check between the Control Panel CPU (CPL P.C.B.: IC1/CPR P.C.B.: IC1) and the MAIN CPU (MAIN
P.C.B.: IC6)
When power is turned on, the model checks communications between the MAIN CPU and each Conirol Panel CPU. If an error
is detected, the following message is displayed on the LCD.
CAUTION!!
** ERROR in CPU data transiniasion ae
Please try turning off and on again.
If this message appears again,
This unit needs repairing.
If this error occurs, perform the Control Panel CPU check from within the service mode. Using the self-diagnostic function, it is
possible to determine which CPU (CPL/CPR P.C.B.) is suffering trouble.
Mi Service mode
The service mode makes it possible to determine whether the various test modes pass or fail.
The test modes in the following table are presented in an order based on circuit operation, but they are completely independent of
one another. Select a mode as necessary, and run the test or check.
Ne. Diagnostic Part/Diagnostic Device Procedure of Service Mode
MAIN P.C.B.: MAIN CPU peripheral devices 1.Connect the CHECKING DEVICE to CN4 on the MAIN P.C.B. (refer
DRAM (1013) to page I-20).
DRAM (IC11) 2.Turn on the power switch while holding down the CHECKING DE-
EEROM (IC8) VICE switch.
Unassigned
PROGRAM ROM (IC4)
PROGRAM ROM (IC2)
TABLE DATA ROM (IC7)
TABLE DATA ROM (IC5)
RHYTHM DATA ROM (IC14)
10. Unassigned
11. LCD CONTROLLER (IC16)
12. Unassigned
OPONOARWN>
When the power swich is turned on, the LED of the CHECKING DEVICE flashes 12 times . The order of the LED flashes
corresponds to the IC number on the respective P.C.B.s as shown below. If an IC is defective, the corresponding flash
time is longer.
10
(@)
(@)
(e)
= are
Examples 1. MAIN P.C.B./
MAIN CPU ICs OK
' After flashing 12 times, the :
| KEYBOARD SWITCH |
‘ SCANNING test mode is!
' engaged.
2. EEROM (IC8) defective ——>
eh let
---G---Es
3. PROGRAM ROM (IC4) aa
defective
@---e---e=
(e)
— @---@---@Nn
—> e@---| -+-@ w
—> @---@---@~ — @---@---@om — @---@---® 0 — @---@---®@ t
1013 ICi1 IC8 1014 IC16
NOTE : @ indicates short flash time Unassigned Unassigned Unassigned
m= indicates long flash time
¢ KEYBOARD SWITCH SCANNING test
When the power switch is turned on, the LED of the CHECKING DEVICE flashes 12 times and then engages the
KEYBOARD SWITCH SCANNING test mode (see the figure above).
Pressing any of the 88 keys will light the LED of the CHECKING DEVICE, while the LED will go out when the key is
released. The KEYBOARD SWITCH SCANNING test determines whether the key switches and the Tone Generator LSI
(MAIN P.C.B.: 1C103) are working properly or not.
°
°
l
IC GO —> @---@---@0 nm i) 9 i?) oa
y