INSTRUCTIONS
PART 1 - PURPOSE
GENERAL
The type 862 Valve and Circuit tester is a self-contained instrument for making the following types of measurements rapidly and conveniently:
(a) Resistors: Four Ranges. Direct reading Ohm-meter for resistances between 0.1 Ohm and 10 Megohms
(b) Condensers: Leakage and open circuit on Mica and Paper Condensers on direct current insulation tester. Leakage current of low voltage and high voltage Electrolytic Condensers.
(c) Milliamperes: Four ranges of direct current milliamperes. Full scale deflections: ImA, lOmA, lOOmA, 250mA. 100 mV voltage drop at full scale deflection.
(d) Volts D.C: Four ranges. Full scale deflections of lOV; l00V, 250V, 1000V. Meter resistance: 1000 Ohms/Volt.
.(e) Volts A.C: Four Ranges Valve Rectification. Full scale deflections: l0V, 100V, 250V, 1000v,
(f) Output Volts: Identical with A.C. ranges.
(g) Valves: Merit test on direct reading scale and short circuit or leakage between elements of all common type receiver and small transmitter valves.
PART 2 - OPERATING INSTRUCTIONS.
POWER SUPPLY:
The type 862 Valve and Circuit Tester can be operated from either A.C (200 to 260 volts) or from a 6 Volt Accumulator.
The 5 pin plug on the supply line of the instrument, coming through a hole inside the small compartment on the top of the case, is wired according to the circuit given below:-
0 240V 0
0 6v - 0
0
Earth
(a) A.C. Operation. The three core power cord supplied with the instrument and fitted with a 5 pin base is wired according to S.A.A. rules, green is earth, red and black 240 Volts A.C. After connecting the power cord to the Mains and inserting the plug on the supply line into the 5 pin base the instrument is ready for use.
(b) Operation from 6 Volt Battery. The 5 pin plug on the instruments supply line has to be inserted into the 5 pin base on the battery cord and the battery cord connected to a 6V accumulator.
The current drawn from a 6V battery is approximately 1.75 Amperes. When a valve is inserted for emission test the current drawn from the battery may raise to 6 Amperes according to the filament current and the voltage of the valve under test
MULTITESTER RANGES:
NOTE:- It is necessary to have the instrument connected to the power supply (A.C. or battery) for all tests except Milliamperes, D.C. Volts and the Low Ohms, Ohms and Ohms x 10.
MEGOHMS:- The voltage across the test prods is 225 volts and care has to be taken not to touch them when the Megohm test is carried out. However since the maximum power present is only a fraction of a watt a shock would be more unpleasant than dangerous -
Before taking a reading the switch in the left hand bottom corner is placed into "MEGOHMS" position and the test prods shorted together. Adjust the instrument to full scale deflection by means of the "LINE ADJUST" switch (top left hand.) When the prods are placed across the points to be measured the meter will show the resistance. Multiply the reading on the Ohms (top scale) by 500 to obtain the resistance value. The Megohm range which extends from 0 to 10 megohms can be used to measure high resistors and potentiometers and for testing insulation properties of component parts like sockets etc.
OHMS:- Two ranges are available, both operated from the dry cell placed in the compartment on the top of the cabinet, Place left hand bottom switch into "OHMS" position and right hand bottom switch into either "OHMS" or "OHMS x 10" position as required. Before taking a reading, short the test prods together and adjust the instrument to full scale deflection by means of the control marked "OHMS ADJ." Read the resistance on the Ohms scale. Multiply value by 10 for the "Ohms x 10" range.
LOW OHMS:- This range, for which the voltage is applied by the battery and which extends from 0 to 30 ohms, allows the measurement of resistance values as low as .1 of an ohm which gives a reading of half a division. It can therefore be used to check poor contacts, short circuits in coils, dry joints etc.
The left hand bottom switch is placed into "OHMS" position and the right hand bottom switch is placed into "LOW OHMS" positon. The pointer of the instrument will go up scale and has to be adjusted to full scale deflection by means of control marked "OHMS ADJ."
When the test prods are shorted together the pointer will not return exactly to zero owing to the resistance of the test leads themselves.
NOTE:- Do not leave the right hand switch in "LOW OHMS" position when not using this range, because this will exhaust the battery in a very short time owing to the high current drain.
ELECTROLYTIC CONDENSERS:- The Valve and Circuit Tester is provided with two ranges for the test of either the low voltage type electrolytic condenser up to 25 volts test voltage or the high voltage types which are encountered in the filter net-work of the power supply in wireless receivers etc. The rotary switch in the left hand bottom corner has to be set accordingly. Preferably alligator clip should be placed on the test prods and the connection across the electrolytic condenser under test made permanent.
NOTE: IT IS IMPORTANT TO OBSERVE THE CORRECT POLARITY OTHERWISE THE ELECTROLYTIC CONDENSER WILL BE DESTROYED.
The direct reading dial on the instrument will show the condition of the condenser. If an electrolytic condenser has not been used for sometime it will be necessary to allow it to "form" for a minute or two after it has been connected for the test. The pointer of the instrument will, if the condenser is good1 gradually go down the scale, finally becoming stationary,
NOTE:- If the condenser is wired into a piece of equipment it will be necessary to disconnect the positive lead of the condenser under test from the circuit before making the test.
PAPER CONDENSERS: Leakage or open circuit in paper condensers can be detected. Turn left hand rotary switch to "Paper Cond. Test." Now apply the prods across the condenser. In case the condenser is in parallel to a resistor or another component or an Electrolytic Condenser it will necessary to disconnect one end. For sizes from 0.1 mfd. or over clip test prod onto condenser and observe the neon. On a good condenser the neon will flash regularly, the period of the flash depending on the size of the condenser, For lower capacity values than 0.1 mfd. touch the terminals of the condenser with the prods and watch for a single flash that should occur. Very low values (1000 mmfd and lower) will only generate a very minute flash and the neon should be watched closely. A second flash will not take place unless the condenser is discharged or the polarity reversed.
A pronounced continuous glow in the neon will indicate a leakage. Sometimes a faint glow will be present, especially when the flexible cords of the test prods are placed close together or the operators hands are touching them, This will indicate a leakage and is quite insignificant.
MILLAMPERES: The left hand rotary switch is placed into mA position and the correct range selected by means of the right hand rotary switch. Always take the initial readings on the highest range first and switch to lower ranges if readings obtained are too far down the scale.
D.C. VOLTS: Turn left hand rotary switch into "D.C. Volts" position and select the correct range on the right hand bottom switch. Always take a reading on the highest range first to avoid overloading the instrument.
A.C. VOLTS: A valve rectifier is incorporated in the tester for A.C, volt ranges. Turn left hand rotary switch into "A.C.Volts" position. Right hand switch serves as selector for the
range.
NOTE: THE INSTRUMENT MUST BE CONNECTED TO THE POWER SUPPLY (A.C. OR BATTERY) TO ALLOW THE RECTIFIER VALVE TO OPERATE.
Measurements on the A.C. line can be taken notwithstanding the fact that the instrument is plugged into same.
It will be noted that on the lower A.C. ranges the pointer will advance a few degrees above the zero. This is due to the use of a valve as a rectifier; this idle current is caused by some electrons reaching the plate owing to their initial velocity despite no voltage on the plate. No inaccuracy however is caused by this fact. The effect will not be so apparent on the higher ranges.
OUTPUT VOLTS: The "Output Volt" ranges use the valve rectifier. A built in condenser of 2 Microfarad blocks the D.C. from the signal, Set left-hand switch into 0/Pt. V. position and select correct range with right hand switch.
VALVE TESTING
I. Plug the instrument into power supply and switch on Turn the bottom left hand switch to position marked "LINE CHECK." The meter needle should now swing over to full scale deflection. Should the needle stop above or below this point, adjust by means of the top left hand switch marked "LINE ADJ." It is important in some districts to check the line voltage constantly. When testing a valve with the tester operating from a 6 volt battery it is necessary to adjust line with valve under test in its correct socket, after carrying out the operations 2 and 3 (Below).
2. Select correct filament voltage as shown on chart.
3. Plug valve into correct socket as shown on chart.
4. Test for inter-element shorts and leakages after waiting for valve to heat. A shorted element or leakage as high as 100,000 ohms will cause the neon electrodes to show a definite glow. A very faint glow, which may be apparent even with the valve out of a socket, can be disregarded,
NOTE: UNDER NO CONDITION CARRY OUT ANY FURTHER TESTS IF
ANY SHORT IS INDICATED, AS THE METER MAY BE SERIOUSLY
OVERLOADED; RESULTING IN THE PERMANENT DAMAGE OF THE
MOVEMENT. If the valve passes the above test, proceed as follows
5. Move bottom left hand switch to position marked "MERIT."
6. Turn selector switch (Middle right hand) to number shown on chart.
7. Adjust range control (Middle potentiometer below meter) accurately to correct number shown on chart.
8. Press button marked "MERIT" and the meter will show directly the condition of the valve. When testing diodes the merit button must be only depressed for the section marked TA and PA and the button marked diodes for the selector switch numbers with the suffix DA. On no account press either button before valve is heated sufficiently to give full emission or for a period longer than three (3) seconds which is ample time to read the condition of the valve.
The reading of diode plates will vary by as much as 20% to 50% between various valves of the same type; but approximately equal readings will be obtained for the diode plates of any one particular valve.
9. TESTING OF 1.4 VOLT VALVES: For merit test on these valve, press the diode button. DO NOT use the MERIT button, as this might cause damage to the valves.
10. This valve tester indicates "end-of-life" point, so far as emission is concerned. The emission readings of new valves have no direct significance, provided they are above this point.
NOTE: To identify the shorting of elements, the following information can be utilized.
Selector Switch Position Number: (NOTE: The purpose of this switch is to select that electrode in the valve which collects enough electrons from the cathode to serve as an emission indicator,, Generally, this is the electrode nearest to the cathode),
1. Control or screen grid.
2. Plate
3.& 4. Filaments (not shown on selector switch,)
5. Cathode
6. Supressor-screen or osc-grid.
7. Osc.-grid or plate
8. Top cap or control grid on screen grid valves.
Method of Calibrating Valves not Listed:
Take two or three valves of type required and follow this procedure:
1. Check line voltage,
2. Set filament switch to correct filament voltage of valve
3. Turn bottom left hand switch to "MERIT", turn Range Control to about (5) and plug in valve, connecting grid cap, if any.
4. Depress Merit Button and rotate selector switch, setting it to the point giving the highest reading on meter.
5. Now advance Range control until meter reads between 90 and
100 (on the voltage scale). Repeat above with valves available, then note readings such as Socket No. Filament, Range settings and Selector position for further use.
The Use of The Adapter Panel:
To provide test facilities for the valve which are only now being released on the market, and to cover those which will be available shortly, the adapter panel has been included as an integral part of model 862 Valve and Circuit Tester.
The adapter panel which is mounted in the front lid is connected to the main instrument by means of an octal plug and also a banana plug. These are connected to NO.7 socket and the TC socket respectively. This makes it possible to select a suitable electrode by means of the Selector and also to supply heater voltages.
If the valve to be tested is listed in the chart, proceed as directed under Valve Testing, Sections 1-10. In the case of valves which are not as yet listed, proceed in accordance with the directions shown in the proceeding section (Method of Calibrating Valves Not Listed).
The sockets F, G and H are for Loctal-based valves. Sockets J and K are for Octal-based valves, in which pins Nos. 1 and 8, and pins 7 and 8, are the heater connections respectively, Socket E is for type 832 Valves, whilst sockets N and D cover the miniature types, including 9000 series. Socket C is for acorn valves and sockets A and B cover European types of 5 and 7 pin valves. Positions L, M, 0 and P are provided to permit the inclusion of any future types of sockets. This precludes the possibility of the Tester becoming obsolete. A circuit diagram of the adapter panel is provided at the end of the book.
NOTE: If a valve is not listed, care must be taken to apply the correct filament voltage and to choose that socket which has the correct filament connections for the valve to be listed,
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