pdf117 code 41 -> U100 on diag_12
pdf53 display analog description
pdf54 display output amps are on board A4 and A10.
pdf244 A2 LED board
pdf247 A3 interconnect board diag_3
pdf251 A12, A13, and partial A4 channel 1 & 2 attenuator diag_4
pdf254 A4 vertical preamp and control diag_5
pdf257 A5 CCD board
pdf260 partial A2 LED bd, partial A3 intercon bd, partial A5 CCD bd
pdf263 partial A6 display board DISPLAY DIGITAL diag_8
pdf266 partial A2, A3, A4, A6, A9, A10 DISPLAY ANALOG diag_9
pdf92 section 3, MAINTENANCE
pdf111 section 3.20 TESTING AND DIGNOSTICS
pdf270 A7 power supply board diag_10
pdf273 A8 memory board
pdf276 A9 MPU board ser#X diag_12
pdf279 A9 MPU board ser#Y
pdf283 A10 trigger board
pdf286 A11 clock generator
pdf288 A11 timebase board
pdf291 A11 partial timebase board fast ramp time interpolator diag_16
pdf292 functional interconnect diagram
pdf293 beginning of signature analysis section

The failed EAROM, U100, is in the upper right corner of
pdf276, diag_12, MPU control.

The X & Y output phase splitters are on A4 pdf266 diag_9 DISPLAY ANALOG
The X & Y DACs are on A6 pdf266 diag_9 DISPLAY ANALOG
TP900 on A6 pdf266 diag_9 DISPLAY ANALOG taps voltage on DAC TIA out.
TP1420 on A6 pdf266 diag_9 DISPLAY ANALOG: voltage going to Y phase splitter.
pdf164 A5 test point and adjustment locations including tp900/1/2
pdf177 B.3: test point and adjustment locations tp900/1/2,810,400 
TP900 is ground reference
pdf224 U100 (A9U100) is tek# 156-1654-00, T1282 (Xicor) X2201-30
pdf188 REPLACEABLE PARTS