IBM 3274 51C Maintenance Information page 59

C F
3 4
Map A120 Power Ind. ON
orOFF
PAGE 9 OF 12
041
• Measure +5VDC at any board D03 pin within the group of
sockets A2 through G2. *K*
Is the +5VDC within the limits of +4.6 to 5.5V7
Y N
042
Is tho +5VDC missing7
Y N
043
• Replace the TSR supply No.2.
Go To Map A100, Entry Point A.
044
• Switch power off.
• At the TSR power supply assembly board No. 2 (Loc.
01 EI, disconnect the two 15 pin plugs Pl and P2. *L *
• Switch power on.
• At the disconnected power supply No.2, measure +5VDC
at jack J1 and J2 pin 2 (+1 and pin 12 (-I. See Figure B-3.
Is the +5VDC still missing7
Y N
045
• Switch power off and reconnect previously
disconnected power supply No. 2 plugs P1 and P2.
*M*
Go to Page 6, Step 020, Entry Point C.
046
• Switch power off.
o
Replace the TSR power supply No.2.
Go To Map A100, Entry Point A.
047
Go to Page 4, Step 016, Entry Point B.
048
Go to Page 8, Step 038, Entry Point E.
3-32
MAP A120-9
*K*
These sockets receive their voltages from TSR supply No. 2
when two power supplies are used (dua\).
*L*
Disconnect all loads from TSR supply No. 2 and determine if
overload is causing +5V to be at OV.
*M*
TSR No. 2 is not causing power problem.