Manufacturer:Hewlett-Packard
Model:HP-5480A
Serial Number: 5480A: 852-00171
5486A: 852-00166
5487A: 920-00104
Year of Manufacture:IC date codes 1968::1971, mostly late-68::early-69
Date of Receipt:~ 2003
Source:(surplus)
State upon Receipt: Good condition. No manuals. CRT trace, signal can be displayed from inputs, but there seems to be a problem in processing. See Log entry of 2022 Apr 25.
Boards are mostly of early series.
Labeled with sticker from B.C. Children's Hospital.

Date:2015 Sep
Procedure: Schematics manual obtained: 5480-90013, "Printed Jan 1971". Source: ebay. Schematics only, Theory of Op and system structure are in a separate manual.

Date:2022 Apr
Procedure: Board and Assembly complement:

Where Assembly Series Description
A1 Display
A1 5480-60013 852 Deflection Amplifiers
A2 5480-60025 832 Calibrator
A3 1200-66505 REV A High Voltage Rectifier
A4 1200-66515 REV A High Voltage Regulator
A2 Memory, Clock, DACs
A1 5421-6001 744 Sense Amplifier
A2 5421-6002 744 Inhibit Generator
A3 5421-6001 744 Sense Amplifier
A4 5421-6002 744 Inhibit Generator
A5 5421-6003 744 Decoder Gate
A6 5421-6003 744 Decoder Gate
A7 5421-6004 744 R/W Generator
A8 5421-6004 744 R/W Generator
A9 5480-60010 832 Horizontal DAC
A10 5480-60009 852 Vertical DAC
A11 5480-60020 852 Voltage Regulator: +/-19.5
A12 5480-60073 928 20MHz Clock
A13 5480-60011 852 Memory Timer
A14 5480-60022 832 Memory Logic
A3 Accumulator & Address Register
A1 5480-60001 832 Preset Detector
A2 5480-60004 852 Accumulator Control
A3 5480-60002 852 High Speed Accumulator (Bits 0-3)
A4 5480-60003 832 Accumulator (Bits 4-7)
A5 5480-60003 832 Accumulator (Bits 8-11)
A6 5480-60003 832 Accumulator (Bits 12-15)
A7 5480-60003 832 Accumulator (Bits 16-19)
A8 5480-60005 832 Accumulator (Bits 20-23)
A9 5480-60007 852 Address Register (Bits 0-1)
A10 5480-60006 832 Address Register (Bits 2-5)
A11 5480-60006 832 Address Register (Bits 6-9)
A12 5480-60008 832 Address Register Control
Where Assembly Series Description
A4 Main Frame Lights & Switches
A1 5480-60012 832 Light Driver & +/-18V Indicator
A5 Power Supplies
A1 5480-60014 852 Low Voltage Regulator: +5, -7.5, +/-12
A2 5480-60015 832 High Voltage Regulator: +/-50, +200
5486A Process Control
A1 5486-60011 852 Input Buffer & Trigger
A2 5486-60010 832 Time Base B
A3 5486-60009 852 Time Base A
A4 5486-60008 832 Time Slot Decoder
A5 5486-60003 852 Light Driver Control
A6 5486-60014 832 Logic C
A7 5486-60006 852 Logic A
A8 5486-60005 832 Program Selector A
A9 5486-60004 852 Program Selector B
A10 5486-60007 852 Logic B
A11 5486-60002 832 Shift Control B
A12 5486-60001 832 Shift Control A
A13 5486-60015 852 Logic D
5487A Four Channel Input (w Option 01)
A1 5487-60001 908 Four Channel Input Amplifier
A2 5485-60004 852 Sample & Hold
A3 5485-60003 920 ADC
A4 5487-60004 908 Four Channel Switching Logic A
A5 5487-60005 908 Four Channel Output Amplifier
A6 5485-60020 908 Switching Logic B (Option 01)
A7 5485-60009 920 Interface

Date:2022 Apr
Symptoms: Trace is bright, intensity control has no effect, eventually reduces to bright dot on left of CRT.
Analysis: +50V supply is at +39V. +/-50V board set up in test jig with two 24VAC transformers. Oscillation on input & output lines during portion of 60Hz cycle. Sense transistor 2N3053 is being operated over Vce spec. Removed and tried with higher V transistor but still some oscillation.
Solution: Original replaced, board reinstalled to measure actual load current. Now works, output is clean. May have been just bad edge connector contact. Current into CRT PS board measured at 78mA @ 47V.

Date:2022 Apr
Procedure: A1 (Display) compartment, boards and CRT area damp-wiped.
A2 compartment damp-wiped.
A3 (Accumulator/Address) compartment and boards damp-wiped. Boards towards rear have some mold/grime on lower portions. Some corrosion on traces and TI IC pins. Isoprop and damp-wiped.
A4 compartment and board damp-wiped.
A5 (PS) boards damp-wiped.
5486 case, frame and boards damp-wiped.
5487 case, frame and boards damp-wiped.
5480 case, frame damp-wiped, upper & lower covers washed.

Date:2022 Apr 06
Procedure: Observation: Circuit of A3A2U3.6 noticed to have lower resistance (-probe GND) than other outputs of same IC, all having equivalent circuits (1 output, 3 inputs). Measured in test setup, HIGH level of U3.6 is 3.7V while others are 3.9V. Logic operation is fine.

Date:2022 Apr 07
Procedure: In operation, signal can be captured and displayed. Setup: SYNC LINE, MODE AVERAGE, SWEEP 10mS, SWEEP COUNT 1, CHANNEL 1 ON, 60 Hz to channel 1, DATA mode. Press CLEAR, START, DISPLAY.

Date:2022 Apr 07
Symptoms: Switching between INPUT vs DATA on 5487, INPUT was showing 'analog' version of signal, then digitized. When switched to DISPLAY mode, noisy unsynced 60Hz appears, looking like an open circuit.
Analysis: Looks like part of signal path is not switching to INPUT but remaining in DATA. Presumably normal behaviour.

Date:2022 Apr 07
Symptoms: Vernier level adjust on channel 3 is loose.
Solution: Plastic coupling broken. Glued.
Mounting bar for pots on channels 1 & 2 had been bent, apparently to correct for to-short spacers between switch body and pot mounting bar. Manufacturing flaw. Mounting bars straightened, washers added on all 4 channels to add space.

Date:2022 Apr 08
Procedure: PRESET/NORMAL knob tab had been broken off (was style like the TOTALISER knob). Replaced with cylinder-style knob (note replacement has different set-screw drive-key and thread size than other knobs on unit).

Date:2022 Apr
Procedure: Examination of operating manual and schematics indicates rear-panel system-interconnect connectors J15::J18 provide sufficient functionality to test and exercise many aspects of the 5480.
Controller program and adapter hardware created.

Date:2022 Apr 25
Symptoms: Conversion is not linear e.g. the slope of a triangle wave is not straight, instead having bursts of semi-random variation (pattern does appear to be same at same points in cycle). Error bursts appear around vertical low-order bits, ~32.
Also, process termination by preset sweep count only works for 1 & 2 sweeps count.
Analysis: During exercise tests with new controller, two faults noted: shift-left of 1 in accumulator fails from 4th bit to 5th bit when 3rd bit is 1, and counting up results in random extra increments e.g. counting up 0x10000 from 0 results in 0x10018.
Board A3A3 (high-speed accumulator) removed for bench testing. FF AC3 will set and reset, but during shift-left the clock signal appears riding at low amplitude on the Q & nQ logic levels. U4 (FF AC3) failed with internal short of pins 8 & 9.
Solution: U4 74H72 replaced with 7472. Speed questionable but seems to work.
Unit now appears to be working properly. The sweep-count preset failure would be explained in that this function uses memory locations above 1000, and thus relies on the accumulator for operation.

Date:2022 Jun 11
Procedure: Wire to 86A13.H opened and 86A13.7 grounded to allow for simpler remote control. With these alterations only SVQ_SUB needs to be asserted to enable remote control and the AR0/1 address bits will not be altered during remote control.

Date:2022 Jul 07
Symptoms: Similar problem to that of Apr 25: coarse conversion around low-bits and sweep count preset only works for 1 & 2 count.
Analysis: Functioning of PREP state figured out and then examined. Shifting and preset-limit-bit detection seems to be working correctly. Controller shows sweep count in memory 1020:1023 is not incrementing properly: sweep count oscillates 1-2-3-2-3-2-3-2-3-etc. Bit 2^0 counts properly but bit 2^1 sticks 1 without generating a carry. U2.8 noted to have poor LOW level, ~ 1V.
Board A3A3 removed again for bench testing, with monostable mock-up to generate 100nS clock pulse. Signal on pins U2.8 and U2.9 observed to be the same (FF AC0). Pins are internally shorted, same fault as with U4 although symptoms are not exactly the same.
Solution: U2 74H72 replaced with 7472.
Unit again appears to be working properly.

Date:2022 Jul 10
Procedure: Observation: With controller, sweep count after calibrated average processes (fixed sweep count) appears to be half what would be expected. 
7:   0x3FC:  0x000041 0x000041 0x000040 0x000040
4:   0x3FC:  0x000009 0x000008 0x000008 0x000008
3:   0x3FC:  0x000005 0x000004 0x000004 0x000004
2:   0x3FC:  0x000003 0x000002 0x000002 0x000002
1:   0x3FC:  0x000001 0x000001 0x000001 0x000001
0:   0x3FC:  0x800000 0x800000 0x800000 0x800000


  Unit Log
HP-5480A DSA 		bhilpert
2022 Apr