475

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The Tektronix 475 is a portable dual-trace oscilloscope with dual time-bases similar to the 465, but with 200 MHz bandwidth and a maximum vertical sensitivity of 2 mV/Div. It is all solid-state except for the CRT. It was introduced in November 1972.

A revised version, the 475A, has 250 MHz bandwidth and a maximum vertical sensitivity of 5 mV/Div. The 1106 is a battery pack for the 475.

The optional DM44 multimeter attaches to the top of the instrument.

Key Specifications

Bandwidth 200 MHz (475), AC cutoff 10 Hz, switchable BW limit 20 MHz
Rise time 1.75  ns (475)
Deflection 2 mV/Div to 5 V/Div, 1-2-5
Cascaded mode 400 μV/Div, 50 MHz with CH1 input connected to CH2 VERT SIG OUT
Time base 10 ns/Div to 500 ms/Div, 1-2-5, and ×10 magnifier
Input impedance 1 MΩ // 20 pF
Triggering 0.3 Div (int) or 50 mV (ext) to 40 MHz, increasing to 1.5 Div/250 mV at 200 MHz; AC coupling >60 Hz; LF REJ >50 kHz, HF REJ <50 kHz
X bandwidth 3 MHz
Z axis input 5 Vp-p, 50 MHz
Calibrator 1 kHz, 30 mA / 300 mV square wave
Outputs CH2 Vert Signal Out, 20 mV/Div into 1 MΩ or 10 mV/Div into 50 Ω; A and B +GATE OUT, +5 V; Probe power jack
CRT 8 × 10 cm², P31 phosphor (P11 opt.)
Power 110, 115, 120, 220, 230 or 240  VAC ±10%, 48-440 Hz, max. 100 W

Internals

The 475 uses a number of Tek-made integrated circuits, including the 155-0032-01 input preamplifier, 155-0085-00 input amplifier, 155-0078-00 vertical amplifier, 155-0091-00 channel switch, 155-0082-00 vertical output amplifier, and 155-0049-00 sweep control.

Links

Common Problems

The 475 series scopes use tantalum capacitors. They are known to short out and bring the scope down. Typical symptoms will be no trace, or powering on and going off in few seconds due to built in foldback protection. The shorted capacitor in the power rails will down one (or more) of them and causing entire scope to be non functional.

Quick way to troubleshoot is, after powering off and ensuring all capacitors are discharged, check resistance to ground on each power supply rail and identify the shorted power rail. Then trace the offending tantalum capacitor with the help of schematic.


Pictures