Home Digital (measurement) tools
HP 1600A Logic Analyzer

HP 1600A Logic Analyzer

Gotten from the inheritance of Domaine l’Espitalet. This device is one of the first logical analyzers from HP and a companion of the HP 1607A I already have. The device seemed in good physical shape, just a bit dirty. But sadly enough it did not work. A quick measure of the +5V showed that no power was present there.

The insides looked quite clean too:

Repairing the device

First step is to get access to the power supply. First remove the A1 board, taking care of the connectors at the top:

For the top right ones the PCB has markings that echo the plugs at front.

Power supply

The schematic was stitched together from the service manual:

Disconnecting everything showed that +12, -12, +5 were all fine, until I put load on the +5V line. Even 200mA dropped it to 200mV.

Part numbers in that power supply:

Q1, Q2M552 4-433Hfe=43, Hfe=29
Q32N3053
U1 case1826-0147 7812
U2 case1826-0221 7912
U1, U2 brduA723Voltage regulator

The current sensing resistors seemed fine at 0.5ohm.

© 2024 by Frits Jalvingh. All information in here can be freely used (MIT License)