The first question – we may ask , what type of DIMM are you testing ? SDRAM DIMM or DRAM DIMM?
To test PC66 PC100 PC133 (SDRAM) DIMM – you need to use the SDRAM Adapter with the base tester to correctly identify and test the modules.
To test EDO or Page Mode (DRAM) DIMM – you need to use the DRAM adapter to correctly identify and test the modules.
You can identify a SDRAM module by the chips marking , typically :
PC133 SDRAM chips are marked with a number 7.5 at the end of the part number.The number identify the chip as a 8ns which is the speed or access time.
PC100 SDRAM chips are marked with a number “8” at the end of the part number.
PC66 SDRAM chips are marked “10 ,12” or 10ns & 12ns.
Most SDRAM DRAM Chip package are TSOP package which are very thin and flat.
For DRAM chip– look for a ”60” or “70” numbering mark on the chip- it denotes the access time or speed of 60ns or 70ns respectively. The chip packaging for DRAM are much thicker in height compared with the SDRAM chip
A fully functional SP3000 tester with the correct test adapter will Auto-Id all JEDEC standard module for size/capacity, device configuration, access time (speed), parity / non parity/ ECC and voltages.
Check all connection point for firm connection - Device Under Test (DUT) and Test Socket, Test Adapter and Tester.
CALIBRATION : For SDRAM User, refer to Appendix B of the SP3000 operation manual for a simple one step SDRAM CALIBRATION PROCEDURE. This calibration is required every time the SDRAM Test Adapter is inserted to a different SP3000 Base Tester for the first time
If the SP3000 fail the test, check and view the result message. Typical failure messaage associated failure are as follows :
Walk Address Failure - checks and detect open/short on address pins and bad address decoder.
Walk Data Failure - checks and detect open/short on data bits
Marching Failure – checks and detect bad cells and decoder interaction problem
Checkerboard Failure – checks and detect for bad cells, decoder interaction problem.
Pre-heat Test Failure– checks and detects reliability during chip warming –up.
Voltage bouncing test – check and detect modules with noise related problem
Loop Test Failure– to simulate module burn-in situation
For SDRAM Testing:
Walk address failure - check and detect for open/short on address pins and bad address decoder.
Walk data failure test - check and detect for open/short data bits
Marching failure - check and detect for bad cells, decoder interaction problem
Checkerboard failure - check and detect for bad cells, decoder interaction problem.
Burst test failure - checks for faulty chip that fail to read and write during consecutive clock cycles.
Chip select test - checks for assembly shorts and open on the CS pins
DQM failure test - checks for shorts and open on the SDRAM chip input and output masking ability
WP fail test - check for module that is PC-100 Intel compliance.
If your module is a known good module that works on the computer- but fail on the SP3000, it might be caused by a worn out test socket , or defective test adapter. Contact CST for an RMA number if you have tried all the above.
Occasionally you might chance upon certain modules that the tester identify as eg 64ns instead of 60ns, this can be caused by several factors:
Signal degradation due to the chip loading effect on the SIMM or DIMM module, the result only happen to one or two types of module, typically with a sizable amount of chips mounted on board.
If the timing is consistently high irregardless of type of module, then contact CST for RMA number to have your tester checked out.
If the [SPD data and address test] is selected in the test pattern, the tester will perform a SPD read / write verify comparison after completing functional test.
If the original SPD data saved and stored in the tester buffer does not match the programmed SPD on the memory module, then– the tester will fail “ SPD Data Test”.
Certain SDRAM DIMM modules are assembled with preprogrammed SPD EEPROM which are software write protected, you will not be able to reprogrammed this type of EEPROM again. Check with your supplier if you are not sure.
Solder shorts on the SPD pins could also result in “Fail SPD Address Test”, perform a visual inspection on the SPD EEPROM leads.
A defective EEPROM which is incapable of data retention and will also fail “SPD data test” . Try rewriting the SPD several times and it still fail- replace a new SPD EEPROM chip.