Diagnostic Control/Interface; Power On Diagnostics - Lexicon MC-1 Service Manual

04 = Counter Failure.
05 = Non-Volatile Data Failure. The data stored in non-volatile memory during the Pre-Burn In test does
not match the value tested during the Burn-in Loop.
4. aYYYYYY: Failing address location. The address, in hexadecimal, where the failure occurred.
5. wZZZZZZ: Value Written. The target value, in hexadecimal, which was written to the address where the
failure occurred.
6. rQQQQQQ: Value Read. The actual value, in hexadecimal, which was read from the address where the
failure occurred.
In addition, the error log can be viewed on an external PC or terminal via the serial debug port. The error
log is sent to the serial debug port when the MUTE F.P. button is used to select the error log or using the
SHIFT/ON infrared command if you are in the EXTENDED DIAGNOSTICS. The IR command can be sent
to the MC-1 via the handheld remote or sent to the MC-1 using IRTX.

Diagnostic Control/Interface:

Various combinations of button pushes are used to control diagnostics activity. During Power On
Diagnostics, three options are available: skipping the Power On Diagnostics, entering Extended
Diagnostics, or proceeding to the next test. Each of these options is described below.
Skip Power On Diagnostics:
Simultaneously pressing the VCR and TAPE buttons will skip the Power On Diagnostics routine and put the
unit into operating mode. The MC-1 periodically checks for this button combination during Power On
Diagnostics and will attempt to skip any remaining tests when this command is detected.
Enter Extended Diagnostics:
When power is applied to the MC-1, the VFD and the front panel LEDs are lit for 3 seconds. To enter
extended Diagnostics, press and hold down on the front panel the REC/ZONE2 and EFFECT buttons until
the end of the 3-second interval. The VFD will indicate Extended Diagnostics. Alternatively, during the
interval, press and hold SELECT on the remote until Extended Diagnostics is displayed.
Pressing and holding EFFECT and MUTE following the failure of any test other than the Z80 CPU test will
activate Extended Diagnostics. After a failure occurs the unit will attempt to display the failed test number,
and will execute a loop of the failing test.
Proceed to the Next Diagnostics Test:
Pressing and holding both the BYPASS and REC/ZONE 2 buttons after a failure occurs will cause the MC-
1 to attempt to execute the next power on diagnostic test. Normally if a failure occurs the MC-1 attempts to
enter a test loop to keep the signal lines active as an aid in debugging the failure. At the end of each
successive loop, the diagnostics will check to see if the BYPASS and REC/ZONE 2 buttons are being held.
Depending on the length of the test, the amount of time required to hold down the buttons in will vary.

Power On Diagnostics:

Power On Diagnostics verify the functionality of the basic MC-1 hardware. They do not completely test all
hardware, nor can they fully diagnose a failure. Power On Diagnostics take approximately 20 seconds to
complete. When the unit is powered on, an attempt is made to illuminate the VFD and front panel LEDs for
approximately three seconds. As soon as the Z80, EPROM, SRAM, and VFD are determined to be
functional, the VFD will show.
DIAGNOSTIC TESTS
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Lexicon
5-3