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Sanwa U-50D Operator's Manual

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Summary of Contents for Sanwa U-50D

  • Page 3: Table Of Contents

    C O N T E N T S GENERAL DESCRIPTION 1 Introduction ..................2 2 Specifications..................3 GENERAL INSTRUCTIONS 1 Selection of the Range ..............4 2 Test Lead Connections ..............4 3 Replacement of Batteries ............4 Reading the Scale................. 5 5 Meter Movement Protection.............

  • Page 4: General Description

    GENERAL DESCRIPTION Introduction. is a pocket-size, high performance circuit U-50 tester equipped with a meter movement of 35 micro­ amperes in sensitivity. The high internal resistance of the DC range accurately measures voltage of high impedance circuits. The acrylic front cover admits full light on the scale dial with a mirror to obtain accurate reading.

  • Page 5: Specifications

    Specifications. Measurement Ranges Available. DC voltage: 0. IV 0. 5V 5V 50V 250V lkV (20kn/V) AC voltage : 2. 5V 10V 50V 250V 1000V (8kn/V) DC current: 50/iA 0. 5mA 5mA 50mA 250mA R x l R x 10 R x 100 R x IK Resistance: Range 50k n...

  • Page 6: General Instructions

    GENERAL INSTRUCTIONS Selection of the Range. Ranges are selected by rotating the selector switch. They are arranged around the knob, resistance ranges on the top, AC voltage ranges on the right, DC voltage ranges on the left, and DC current ranges on the bottom. Test Lead Connections.

  • Page 7: Replacement Of Batteries

    Replacement of Batteries. Exhausted batteries should be immediately replaced, because the electrolyte might leak and corrode the internal components. For replacement, see OPERATION -5, Note. Reading the Scale. The meter should be placed level for correct reading. Look at the scale right over where the pointer falls exact­ ly over its image in the mirror.
  • Page 8 Resistors subject Part Nos. Tester ranges to burn R x 1 505a R x 10 5. 56ka R x 100 47. 3k a R x IK DC 0. 1V(5(VA) DC 0. 5V 90k a DC 5 V 841H • 84. 2 a • 5. 41ka R ll •...

  • Page 9: Other Precautions

    Other Precaurions. a The selector switch should not be rotated leaving the test leads connected to power: the movement or the internal components could be damaged. b Avoid allowing the meter to receive severe shock or vibration. Do not leave it where there is high temperature or moisture, or strong magnetic field.

  • Page 10: Operation

    OPERATION DC Voltage Measurements. DC voltage ranges are mostly used for measurements of batteries, B( + ) power, plate, screen-grid and cathode voltages of radio/TV receivers and amplifiers. Their circuits generally have minus potential grounded, though pnp transistor circuits, their plus potential. For measurements, go through the following procedure: a Zero Correction.
  • Page 11 corrector screw at the base of the scale dial. (Fig. 1-1) b Range Selection. The selector switch can be rotated to any one of the six DCV positions. When in doubt as to the approximate voltage present, always start with the highest range. After the first reading, the switch can be reset to a lower range for a more accurate reading.
  • Page 12 c Test Lead Connections. See GENERAL INST­ RUCTIONS^. The test leads connected to the meter are applied across the voltage to be measured, the red lead to plus and the black lead to minus potential of the load. In most cases, minus side is earthed or connected to the chassis.

  • Page 13: Ac Voltage Measurements

    Scale to read : Multiplied by Ranges 0.01 0. IV 0 - 10 0 - 50 0.01 0.5V 0 - 50 0 - 50 50 V 0 - 250 250 V 1000V 0 - 10 AC Voltage Measurements. AC voltage ranges are mostly used for checking the mains, secondary voltages of a power transformer, etc.
  • Page 14 Zero C orrection. See 1-a. (Fig. 2-5; b Range Selection. The selector switch can be rotated to any one of the five ACV positions. When in doubt as to the approximate voltage present, always start with the highest range. After the first reading, the switch can be reset to a lower range for a more accurate reading.
  • Page 15 Measurement of Proper range to be used 250-1000 volts 1000V 50-250 volts 250V 10-50 volts 2.5-10 volts 0-2.5 volts 2.5V c Test Lead Connections. See GENERAL INST­ RUCTIONS^. The test leads connected to the meter are applied across the voltage to be checked. Since alternating current is being measured, the readings are correct to which side of the voltage the test leads are con­...

  • Page 16: Internal Resistance Of The Voltage Range

    Range Scale to read Multiplied by 2.5 V 0 - 2 . 5 0 - 10 0 - 50 250V 0 - 250 1000 V 0 - 10 Internal Resistance of a Voltage Range. Voltage is measured applying the test leads in parallel with the power.
  • Page 17 DC, the internal resistance of the 250 volt range is 250X20,000 = 5,000,000 [Q) = 5,000(kl2), or 5 megohms. When the plate or screen-grid voltage of a triode or pentode of high impedance load and high amplification factor along with small circuit current is checked by a meter of small internal resistance, considerable current flows from the meter into the series load resistance of the tube.

  • Page 18: Dc Current Measurements

    DC Current Measurements. a Zero Correction. See 1-a. (Fig. 3-1) b Range Selection. The selector switch can be rotated to any one of the five current ranges prescribed. When in doubt as to the approximate current present, always start with the highest range. The switch can be reset to a lower range for a more accurate reading.
  • Page 19 Proper range Measurement of to be used 250(mA) 50 - 250mA 50 (mA) 5 - 50mA 5(mA) 0.5 - 5mA 0. 5(mA) 0. 05 - 0. 5mA 50 (/i A) 0 -0. 05mA c Test Lead Connections. See GENERAL INST­ RUCTIONS^.
  • Page 20 Range | Scale to read Multiplied by 0 - 50 0 .5mA 0 - 50 0.01 0 - 50 0 - 50 50mA 250mA 0 - 250 Note. For measurement of a low resistance circuit, the internal resistance of the current range used is connected in series with it resulting in current decrease to cause erroneous reading.

  • Page 21: Resistance Measurements

    Resistance Measurements. a Zero Correction. See 1-a (Fig. 4-1) © © b Range Selection. The selector switch can be rotated to any one of the four Q positions. (Fig. 4-2) For an accurate measurement, use a range which w ill allow the pointer to fall near the middle of the ohm scale.
  • Page 22 Measurement of Proper range to be used 0 - I50n R x l 150H - 1. 5kO R x 10 1. 5kO - 15kn R x 100 15kf2 - 5mgO R x IK c Test Lead Connections. See GENERAL INST­ RUCTIONS^.
  • Page 23 internal batteries are exhausted, and they must be immediately replaced. For replacement, see Note below. After the pointer is properly adjusted, the test leads are opened and are applied across the resistance to be measured. (Fig. 4-6) e Scale Reading. Use the top black scale marked Q for all resistance measurements.
  • Page 24 (2) Use of the battery sheaths. If iron-armoured cells are used in this model, magnetic field effect w ill cause big error of reading. W ith­ out the sheaths, the meter w ill read error on plus side. Always use them when the batteries are replaced.

  • Page 25: Volume Level Measurements

    a resistance range when the meter is not in us. The test leads might be accidentally shorted allowing the internal battereries to become consumed. Volume Level Measurements. Audio output of a tube radio and amplifier where both DC and AC currents are present is checked on AC voltage ranges by placing a non-polarized condenser of 0.1-2 microfarads in series with a meter terminal to block DC component.
  • Page 26 Voltage - 20 log,,, ? 2 Current - 20 log,o-j2 ° Input (E,) j Circuit j O u tp u t;'(E ^ Power - 10 logio— —■ - They are decibels. But they only express input and output by ratio independently from each other, and can not be taken as comparison values.
  • Page 27 For instance, for a 600-ohm line of a uniform impedance on both input and output sides, gain or loss can be readily known by the output dB minus input dB. If the impedance is other than 600 ohms on one side or on both sides, each decibel measured only serves to compare their voltage level.
  • Page 28 is for measurement on the AC 2.5 volt range, and the lower scale on the AC 10 volt range. For the 50, 250 and 1000 volt ranges, l4(dB), 28(dB; and 40(dB) is added respectively to the reading of each range. d Impedance Matching by a Graph.
  • Page 29 Example 1. Providing the meter reads 9dB for the AC 2.5 volt range for a speaker impedance of 16 ohms, the Load Impedance [Q) 16 is followed up, and then to the left at the intersecting point with the oblique line to obtain 15.7 on the Decibel Additon axis.

  • Page 30: Capacity And High Resistance Measurements

    comparison. Loss from connecting the meter to a 600-ohm line is negligible, but when a high impedance circuit is checked, the internal resistance of the meter must be fully taken into consideration. Capacity and High Resistance Measurements, a Zero Correction. See 1-a.
  • Page 31 For capacity. For high resistance. The selector switch is rotated to a specified vol­ tage range, and, connecting the test leads to the external power as shown by the dotted line, the pointer is calibrated to full scale by means of a vol­ tage regulator (for AC) or potentiometer (for DC).
  • Page 32 Note. The static capacity of electrolytic condensers can not be checked. — 30 —...

  • Page 33: Supplementary Data

    SUPPLEMENTARY DATA 1. Schematic Diagram A C V CIKO.'VJ o 0 V (ZOKO/V) E C m A 2 . 5 2 5 0 1 0 0 0 0 . 5 2 5 0 1 0 0 0 0. 5 2 5 0 R X I R X 1 0 R X —...

  • Page 34: Arrangement Of Parts (Rear View)

    Arrangement of Parts (Rear View) — 32 —...

  • Page 35: List Of Main Parts

    3. List of Main Parts D escrip tio n R .S . N am e R e s isto r 15M ohm (f ilm , % W ) , DC 1000V m u lt ip lie r R e s isto r 6M ohm (f ilm , % W ), A C 1000V m u ltip lie r R e s is to r 4M ohm (f ilm , % W ), DC 250V m u lt ip lie r...
  • Page 36 Accessories Available for U-50D For exclusive use of the 1. Shunt Adapter. U-50i> to extend the DC current range (SA-25A) to 1, 5 and 25 amperes. 2. High Voltage Probe. 25kV rating for 20k Qf V to measure high DC voltage.
  • Page 37 T CO., LTD S A N W A M E T fR TO K YO ” Kakuta Bldg., 1-MO Yushima, Bunkyo ku...

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