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Home-brewed Theremins ... and other strange devices

Tektronix Type 576 Curve-Tracer

Tektronix Type 576 Curve-Tracer Front-View 01

From a local industrial measurement equipment reseller I acquired a vintage non functional Tektronix Type 576 Curve-Tracer (first series, manufactured by Tektronix Holland N.V. /Heerenveen in the Netherlands) including several test-fixture units but no component test-adapters. The unit had to be serviced as described below.

Adjustment

To adjust the TEK576 Curve-Tracer, the Calibration Fixture (TEK067059900) has to be used. It provides calibration voltages and currents for the horizontal- and vertical deflection units of the TEK576. In addition, it contains current-loads for testing the collector supply and step generator.  Because this unit was not available, it had to be substituted. Luckily, I was able to find a manual for the calibration unit, containing schematics and circuit description. Although complex, circuit parts, which had to rebuild, could be identified. The circuit provides synchronous pulses of +25V and 0.5V as well as a synchronous 0.5V saw-tooth signal. In addition, a service jack and switch was added to the TEK576, to connect the pulse source and other DC calibration signals.

TEK576 Curve-Tracer Calibration Adaptor PCB 01
TEK576 Curve-Tracer Calibration Adaptor PCB 02
TEK576 Curve-Tracer Calibration Adaptor PCB 03
TEK576 Curve-Tracer Calibration Adaptor PCB 04
TEK576 Curve-Tracer Calibration Adaptor PCB 05
TEK576 Curve-Tracer Calibration Adaptor PCB 06
TEK576 Curve-Tracer Calibration Adaptor Installation 01
TEK576 Curve-Tracer Calibration Adaptor Installation 02
TEK576 Curve-Tracer Calibration Adaptor Installation 03
TEK576 Curve-Tracer Calibration Adaptor Installation 04
TEK576 Curve-Tracer Calibration Adaptor Installation 05
TEK576 Curve-Tracer Calibration Adaptor Installation 06
TEK576 Curve-Tracer Calibration Adaptor Installation 07
TEK576 Curve-Tracer Calibration Adaptor Installation 08
TEK576 Curve-Tracer Calibration Adaptor Installation 09
TEK576 Curve-Tracer Calibration Adaptor Installation 10
TEK576 Curve-Tracer Calibration Adaptor Installation 11


TEK576 Curve-Tracer Calibration Adaptor Installation 12
TEK576 Curve-Tracer Calibration Adaptor Installation 13
TEK576 Curve-Tracer Calibration Adaptor Installation 14
TEK576 Curve-Tracer Calibration Adaptor Installation 15
TEK576 Curve-Tracer Calibration Adaptor Installation 16


HV-Range Reactivation

When I first acquired the TEK576 Curve-Tracer (which was manufactured by TEK Netherlands around 1974) the high-voltage (HV) ranges had been partially deactivated by the previous owner, as marked by a sticker. To reactivate the high-voltage, it was necessary to partially dismantle the collector voltage switch unit, which was quite complicated and took a long time. Soldering points were hidden or blocked by other parts. Nevertheless, the HV could be brought back to full functionality.

TEK576_Sweep-Power-Supply_01
TEK576_Sweep-Power-Supply_02
TEK576_Sweep-Power-Supply_03
TEK576_Sweep-Power-Supply_04
TEK576_Sweep-Power-Supply_05
TEK576_Sweep-Power-Supply_06
TEK576_Sweep-Power-Supply_07
TEK576_Sweep-Power-Supply_08
TEK576_Sweep-Power-Supply_09
TEK576_Sweep-Power-Supply_10
TEK576_Sweep-Power-Supply_11
TEK576_Sweep-Power-Supply_12
TEK576_Sweep-Power-Supply_13



Faulty HV-Transformer

The HV transformer of the early production TEK576 Curve-Tracers contains an isolation compound which is hygroscopic. This leads to high losses and excessive currents within the HV circuit, causing the power supplies over-current protection circuit to switch off. Because there was nothing to loose, I tried to carefully remove the brown sticky wax-like compound. Because the inner construction was unknown, layer by layer was removed using a small knife and pliers. Special care was necessary to not cut the thin wires of the HV winding. After all compound was removed, the windings have been covered by insulation enamel. In addition, the ferrite core next to the winding have been covered by isolation-tape. In the finished reassembled HV circuit, no spark-overs have been noticed, even when the transformer is not entirely encapsulated by compound. The resulting HV and currents are now within tolerances.

TEK576_HV-Power-Supply_01
TEK576_HV-Power-Supply_02
TEK576_HV-Power-Supply_03
TEK576_HV-Power-Supply_04
TEK576_HV-Power-Supply_05


TEK576_HV-Power-Supply_06
TEK576_HV-Power-Supply_07
TEK576_HV-Power-Supply_08
TEK576_HV-Power-Supply_09
TEK576_HV-Power-Supply_10


TEK576_HV-Power-Supply_11
TEK576_HV-Power-Supply_12


TEK576_HV-Power-Supply_13
TEK576_HV-Power-Supply_14
TEK576_HV-Power-Supply_15
TEK576_HV-Power-Supply_16
TEK576_HV-Power-Supply_17
TEK576_HV-Power-Supply_18
TEK576_HV-Power-Supply_19
TEK576_HV-Power-Supply_20
TEK576_HV-Power-Supply_21
TEK576_HV-Power-Supply_22
TEK576_HV-Power-Supply_23
TEK576_HV-Power-Supply_24
TEK576_HV-Power-Supply_25
TEK576_HV-Power-Supply_26


To archive additional cooling, a small fan was added to the cover of the HV compartment as shown in the pictures. The 12V van is operated via a current limiting resistor with lower speed.

TEK576 Curve-Tracer HV-Compartment-Cover 01
TEK576 Curve-Tracer HV-Compartment-Cover 02
TEK576 Curve-Tracer HV-Compartment-Cover 03
TEK576 Curve-Tracer HV-Compartment-Cover 04
TEK576 Curve-Tracer HV-Compartment-Cover 05
TEK576 Curve-Tracer HV-Compartment-Cover 06
TEK576 Curve-Tracer HV-Compartment-Cover 07
TEK576 Curve-Tracer HV-Compartment-Cover 08


Step Generator Amplitude Switch

Additional descriptions under construction!

TEK576_Step-Gen-Amplitude-Switch_01
TEK576_Step-Gen-Amplitude-Switch_02
TEK576_Step-Gen-Amplitude-Switch_03
TEK576_Step-Gen-Amplitude-Switch_04
TEK576_Step-Gen-Amplitude-Switch_05
TEK576_Step-Gen-Amplitude-Switch_06
TEK576_Step-Gen-Amplitude-Switch_07
TEK576_Step-Gen-Amplitude-Switch_08
TEK576_Step-Gen-Amplitude-Switch_09
TEK576_Step-Gen-Amplitude-Switch_10
TEK576_Step-Gen-Amplitude-Switch_11
TEK576_Step-Gen-Amplitude-Switch_12
TEK576_Step-Gen-Amplitude-Switch_13
TEK576_Step-Gen-Amplitude-Switch_14
TEK576_Step-Gen-Amplitude-Switch_15
TEK576_Step-Gen-Amplitude-Switch_16
TEK576_Step-Gen-Amplitude-Switch_17
TEK576_Step-Gen-Amplitude-Switch_18

Readout Display

Additional descriptions under construction!

TEK576_Readout-Display_01
TEK576_Readout-Display_02
TEK576_Readout-Display_03
TEK576_Readout-Display_04
TEK576_Readout-Display_05
TEK576_Readout-Display_06
TEK576_Readout-Display_07
TEK576_Readout-Display_08
TEK576_Readout-Display_09
TEK576_Readout-Display_10
TEK576_Readout-Display_11
TEK576_Readout-Display_12

Variable Sweep Voltage Converter

Additional descriptions under construction!

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Readout PCB LED Conversion

  • IMG_3078_WZ
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  • 93_WZ
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  • DSCN1450_WZ
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Additional descriptions under construction!

Readout LED Light-Pipe

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Additional descriptions under construction!

PE Indicator & Line-Connector

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 Additional descriptions under construction!

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Additional descriptions under construction!

Main PCBs

  • DSCN1263_WZ
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Additional descriptions under construction!

PCB Hinge

  • DSCN1432_WZ
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 Additional descriptions under construction!

Noise Trimmer-Capacitor

  • DSCN1379_WZ
  • DSCN1384_WZ
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  • DSCN1396_WZ
  • DSCN1395_WZ
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Additional descriptions under construction!

LV-Regulator PCB

  • DSCN1254_WZ
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 Additional descriptions under construction!

Indicator Lamps LED Conversion

  • [000146]_WZ
  • [000148]_WZ
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  • DSCN1898_WZ
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Additional descriptions under construction!

Graticule Lamps LED Conversion

  • DSCN1963_WZ
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  • DSCN1974_WZ
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 Additional descriptions under construction!

Dispaly Switching PCB

  • DSCN1424_WZ
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Additional descriptions under construction!

 CRT

  • [000012]_WZ
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  • [000016]_1_WZ
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  • DSCN1598_WZ
  • [000025]_WZ
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  • [000023]_WZ

 Additional descriptions under construction!

 Self-Made Photo Adaptor

  • DSCN1429_WZ
  • DSCN1430_WZ
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Additional descriptions under construction!