Lexicon MPX G2, Service Manual

Page: 73 / 165

Lexicon
5-25
2186 SRAM Failure (14)
When the 2186 SRAM Test fails, Address, Data Sent and Data Received fields are used. All of these fields
will display the information in hex. The Address field will display what the Address (ADDR0-ADDR13 &A14)
was at the time of the failure. The Data Sent field will display what Data was sent to the SRAM (U89). The
Data Received will display the Data received from the SRAM.
When Test Result is selected, the display will read the following:
Last Test: Failed
<> *1 times
* This assumes that the test was run 1 time.
Pressing the >YES button 2 times will display the following if the SRAM Test failed:
(This is an example where DATA 6 is bad.)
Test #13 A:2000
<S:0055 R:0015
In order to determine which bit is bad, the Sent and Received information (which is in hex) must be
converted to binary notation as follows:
The data sent and data received values
in this nibble are different.
Hex Binary
Data Sent 0055=0000 0000 0101 0101
Data Received 0015=0000 0000 0001 0101
These Bytes
are not used Bit 0
LSB
Bit 6 Bad
To exit, press the OPTIONS button and the previous selection will be displayed.
ROM Checksum Failure (14)
When the ROM Checksum Test fails, the Sent and Received fields are used. The Sent Field contains the
checksum value in hex and the Received Field contains the calculated value.
When Test Result is selected, the display will read the following:
Diags: Top Level
Test result >
Pressing the >YES button 2 times will display the following if the ROM Checksum Test failed:
Test #14 A:5000
<S:5000 R:5001
Checksum Value
───┘ └───
Calculated Value
If the ROM Checksum Test fails, it is likely an indication of a defective ROM (U93).
To exit, press the OPTIONS button and the previous selection will be displayed.