Digital Test
Ballantine Laboratories Inc. Autometronic 5500B

Manufacturer: Ballantine Laboratories Inc.
Model: Autometronic 5500B
Year: 1975
Schematic: RE
Max. Rate: 80 - 125 MHz (IC spec)
Display: 7-seg LED
Digits: 8
Logic: TTL

A novel counter with auto-ranging. Rather than selecting the gate time, the operator selects the desired number of digits of resolution. The counter adjusts the display over the sampling cycle to fit that resolution.

- Unit Log -

Serial Number: 121162
Year of Manufacture: 1975 (Component date stamps 7203 to 7535)
Date of Receipt: 2006 Aug 29
State upon Receipt: Good physical condition. Slight layer of grimy dust inside. Non-functional: resets to arbitrary display, not responsive to any input, resolution switch selection not consistent.

Date: 2006 Aug 31
Procedure: -15V supply is 0V. Traced to shorted capacitor (local 220µF/40V filter cap in load circuit of driver transistor). Replaced. Unit is now mostly functional, with the exception that resolution selection is still flaky.

Date: 2006 Aug 31:
Procedure: Logic supply is a little high at 5.5V. Reduced to 5.1V by adding parallel 6.8K resistor.

Date: 2006 Oct 22:
Procedure: Reseating of ICs (low quality sockets) and some soldering cleanup seems to have improved the functioning.

Lamp-test wire rerouted through PCB connector pin 15 to avoid fixed wire connecting boards.


Date: 2006 Oct 25:
Procedure: Dim over-range LED replaced.

Filter cap (10µF,350V) for unused 200V supply removed. The 200V supply was probably used for NIXIEs in an earlier model, why the components for the 200V supply were installed is a question.

Date: 2008 Mar 06:
Symptoms: Does not count or dispay over ~900 Khz.
Solution: Most socketed ICs jiggled/reseated. Functional.

  .. | Ballantine Laboratories Inc. Autometronic 5500B | ..
Early Digital Test Equipment