IBM RT PC 10 Hardware Maintenance And Service page 112

Step 5
The letter of the 37x SRA identifies the failing module within a horizontal
row of modules. The horizontal row is determined by the switch bank
setting that corresponds to the letter in the 21x SRA.
1. Find the switch bank that corresponds to the letter in the 21x SRA.
2. Find the module within the same horizontal row that corresponds to the
letter in the 37x SRA.
3. Exchange the module.
4. Run 110 Channel Memory Checkout.
AB C 0 E F G HI J K L M NO paR
DID A FAILURE OCCUR WITH THE SAME SRN?
YES Exchange the AT 512 KB Memory Expansion Option.
NO This completes the repair.
Problem Isolation Charts 3-67