Telequipment D56

Manuals – Specifications – Links – Pictures

The Telequipment D56 is a 15 MHz dual-channel dual beam oscilloscope produced in the late 1960s.

It uses a mix of tube and solid-state circuitry. In the absence of a D56 manual, the closest manual is that of the D55A, which is an all-tube scope from 1963.

Key Specifications

Bandwidth	DC to 15 MHz (-3 dB)
Rise time	23 ns
Deflection	10 mV/div to 50 V/div, 1–2–5, and ×10 magnifier
Input Impedance	1 MΩ // 40 pF
Sweep Rate	500 ns/div to 5 s/div, 1–2–5, and ×10 magnifier
Features	10 MHz time calibrator (intensity modulated marker) on CH11 using Timebase A
Power	90 - 240 VAC, 50 Hz, ~275 VA
Dimensions	24 cm × 43 cm × 48 cm
Weight	26.7 kg (59 lb)

Internals

Differences between D56 and D55A

The main differences between D56 and D55A are the following:

• Both have 15 MHz Bandwidth. However, at 10 mV/div sensitivity, the bandwidth is limited to 500 kHz.
• 10 mV/div compared to 100 mV/div Sensitivity.
• Circuit boards are used more consistently apart from the vertical amplifiers.
• Mixed transistors and tubes. Still many tubes, but adding transistors gives more possibilities.

Tubes

• 35 tubes + CRT (same CRT as in the D55A).
• Vertical Amplifiers (each): 2×EF184, 2×ECC88, 2×E810F.
• Horizontal Amplifiers (each): V101: ECF80, V102 ECF80, V103: ECC88, V104: ECC88, V105: EAA91, V106: ECF80, V107: ECF80, V108: ECF80, V109: ECF80.
• Time Delay: V302: ECC88, V303: ECC88.
• Trace Blanking: V304: ECC88, V305: ECC88, V403: EF184.
• Regulators Board ? PC23: V301: ECC88.
• Regulators Board PC24: V401: EL86, V402: ECF80.
• CRT: 5" flat-face, double gun, P1 phosphor. 1374K G.E.C.

Transistors

• Nine germanium PNP transistors.
• Motorola LB293, T-119, TO-92, germanium, PNP: TR251, TR252, A; TR101, TR102, B; TR101, TR102. 6 pcs. total.
• Newmarket NKT452, TO-3, germanium, PNP, 3A. TR402.
• Newmarket ACY22, TO-5, Germanium, PNP. 225mW, TR401, TR403. 2 pcs.

Pictures

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  D56 Front View

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  D56 trace

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  D56 Rear View

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  D56 Vertical Amplifiers Side View

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  D56 Vertical Amplifiers Side View

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  Rear View with Transformers and Regulators

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  D56 Regulators

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  Timebase Side View

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  Timebase A top

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  Trace Blanking Board PC27

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  Timing Delay Transistors

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  Trigger? Board Transistors

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  Neutralization Trimmer, do not change

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  Vertical Amplifier Component Side

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  Rear Board on Vertical Side