Using a Multimeter to Measure Memory Chips
There are 64 data pins (D0‑D63) between the mainboard and memory module. To protect these memory data pins, each of the 64 data‑bit pins D0‑D63 is fitted with a small‑value resistor (10 Ω) for current‑limiting purposes. The main working principle of a dedicated tester is to repeatedly test each data‑bit pin of the memory chip via program, checking for breakdown or short‑circuit conditions on data‑bit pins, as well as the clock pins and address pins of the chip.
Therefore, when testing chips with a multimeter, you may adopt a method derived from the dedicated tester. Connect the red probe to ground (pin 1), and use the black probe to measure the resistance of each series resistor. The resistance value obtained corresponds to that of the memory‑chip data bit, by which you can identify the faulty chip. All data‑bit resistances should be identical under normal conditions. This method is less intuitive than using a dedicated tester, yet it can be used to judge whether DDR memory chips are good or defective.
According to the operation manual, memory‑test locations marked 2A and 2B represent single‑bank and dual‑bank configurations respectively. Eight 16‑bit chips are equivalent to two banks; similarly, sixteen 8‑bit chips also constitute two banks.
2A stands for the first bank and 2B for the second bank.
During measurement, the tester cycles through every data‑bit pin of each chip within each bank. A chip is regarded as good if it passes 3‑5 repeated test cycles. Good chips are indicated by "PASS", while faulty chips will display the defective data‑bit pin number.
If the tester fails to enter the test routine after power‑on, common causes include short‑circuited chips or short‑circuited PCB traces. To troubleshoot, desolder the chip and mount it onto a known‑good PCB to verify whether the chip itself is defective.
The memory tester does not test the SPD chip; the SPD chip is optional.
Testing cannot be performed if the golden fingers are burnt. The chips must be removed and installed on a known‑good PCB for fault
