I 177 TUBE TESTER INSTRUCTIONS

I - Preliminary Instructions

Before handling Tube Tester I-177, read the operating instructions carefully. This is a delicate electrical instrument containing a meter and parts that can easily be damaged by mishandling. Pay particular attention to the notices. It also uses voltages sufficient to KILL you. If you don't know what you're doing, get help from someone that does. Remember, it's old and a lot can go wrong in that period of time. Be alert and be careful and stay alive.

CAUTION: After testing tubes, always set all controls to off or saftey positions as indicated in table. Tubes may be burned out if inserted in test sockets before the controls have been properly set.

Control Safety Position
POWER OFF
SHORT TUBE TEST 1
LINE ADJUSTMENT Extreme counterclockwise
A 1
B 1
FIL OFF
MICROMHOS 15000
L 80
R 80
II - SHORTS TEST
  1. Make sure that all controls are in the safety positions, listed in table 1, above.
  2. Plug the power cord of the tester into a suitable a-c power outlet (105 to 125 volts)
  3. Determine the type number of the tube to be tested and locate this type number either in the column headed Tube Type or in the filter Tube Type at the top of the page.
  4. Set selector switch A to the number indicated in column A.
  5. Set selector switch B to the number indicated in column B.
  6. Set selector switch FIL to the number indicated in the column headed either Fil. Volts or Filament Volts.
  7. Insert the tube in the socket indicated in the column headed Socket Letter.

NOTE: When inserting or removing a loctal or acorn tube from a socket, handle the tube as gently as possible. Tube pins pass directly through the glass seals and excessive force will crack the glass. A slight sideways pressure applied to a loctal tube will release the lock and permit easy removal of the tube from the socket.

  1. If the tube has a top cap, attach the clip of the CAP lead to the cap. For acorn tubes, use the ACORN CAP lead and clip. For tubes having a star in the Notations column (such as some listings for the 807, 871, etc.) connect the plate top cap of the tube to the upper left contact of the 6-pin socket C with the 12-inch lead having a clip and banana plug. For some tube listings, other instructions may be present in the Notations column that may direct you to connect the 12-inch lead to other locations. ALWAYS read and pay attention to the Notations column.
  2. Set the POWER switch to the ON position.
  3. To adjust the line voltage, press and hold down the LINE TEST button and turn the LINE ADJUSTMENT knob until the meter pointer is exactly at the LINE TEST position (at 1,500, not at the ? on the scale); then release the LINE TEST button.
  4. After allowing at least 30 seconds for the tube to warm up, turn the SHORT-TUBE TEST switch slowly from position 1 to positions 2, 3, 4, and 5 successively while tapping on the tube with a finger and watching the SHORTS neon lamp. If the lamp continuously or glows during tapping in any of the five positions, the tube contains shorted electrodes and should be discarded without further testing (to prevent damage to the meter) unless and exception is noted in the Notations column. Disregard a momentary flash of the neon lamp while this switch is being turned from one position to the next, since this is due to the charging of a capacitor in the lamp circuit.

NOTE: Before discarding the tube, refer to the Notations column of the test data for the listing of that tube to see if the tube being tested normally appears to be shorted on certain positions of the switch. Thus, for the 1LN5, the notation "Shorts on 4 and 5" in the Notations column means that the neon lamp will normally glow at positions 4 and 5 for good tubes. This tube has no shorts if the neon lamp stays out for positions 1, 2, and 3. Tapping on certain tubes will damage them. Pay particular attention to the Notations column comments.

  1. On tubes having several sections, the shorts test need to be made only once.
III - QUALITY TEST
  1. Test the tube for shorts by following the complete procedure listed above. If the tube is shorted, discard it without making further tests.
  2. If the tube is not shorted, turn the SHORT-TUBE TEST switch to the TUBE TEST position. Do not change any of the other controls used for the shorts test.
  3. Set potentiometer L to the number indicated in column L on the test data.
  4. Set potentiometer R to the number indicated in column R.
  5. Set the MICROMHOS range switch at 3,000.
  6. Press the button indicated in the Press column of the test data, and read the meter on the RED-GREEN scale.
  7. Normally, if the pointer stops in the GREEN sector the tube is good; if in the RED sector, the tube is defective and should be discarde If the pointer stops in the ? sector, the tube is usable for a few more hours but should be replaced soon. For tubes in the Notations column having a note such as "OK over 160" (for example, type 40), read the meter on the 0-3,000 micro ohms scales. Tubes reading higher than the value given in the Notations column are goo Good diode sections may read in the portion of the RED scale marked DIODES O.K. Only diodes reading to the left of this section (to the left of A in REPLACE on the scale) should be considered defective.

CAUTION: Do not press the red AMPL.TEST button while testing rectifier tubes. When testing small diodes, do not press either the AMPL. TEST or a RECTIFIER TEST button, because the high voltage would damage the delicate cathode. Press only the DIODE TEST button as called for in the test data.

  1. If a tube is listed two or more times in the test data, it has two of more sections requiring individual tests, or has two input grids (for example, 6A8 pentagrid converter) requiring separate dynamic tests.
  2. Remove the tube from the socket after the first test is complete Then repeat the quality test for each additional listing in turn. The shorts test should be made only for the first listing, however the tube sectioned covered by a listing is identified in the Notations column in the test data.
IV - MEASURING MUTUAL CONDUCTANCE

This procedure gives a mutual conductance reading in micro ohms for an amplifier tube on amplifier section, instead of a RED-GREEN reading.

  1. Test the amplifier section or section for shorts by following the complete procedure given above. If it is shorted, discard it without making further tests.
  2. If the tube is not shorted, turn the SHORT-TUBE TEST switch to the TUBE TEST position. Do not change any of the other controls used for the shorts test.
  3. Set the potentiometer L at GM (replaces 60 on the dial).
  4. Set the potentiometer R to the number indicated in column R on the test data.
  5. Set the MICROMHOS range switch to an appropriate range for measuring the value listed for Mut.Con in the Notations column of the test data.
  6. Press the button called for in the Press column, and read the meter on the scale to which the MICROMHOS switch is set. This reading is thew mutual conductance of the tube in micro ohms under the element voltage conditions provided by the tube tester.
  7. If a tube is listed two or more times in the test data, remove the tube from its socket after the first test. Then repeat all of the tests except the shorts test for the next listing as if testing another tube.
V - GAS TEST

This procedure determines whether or not an amplifier tube contains too much gas.

  1. Carry out the shorts test procedure given above. If dealing with a multi section tube, the shorts test and the gas test must be made on an amplifier section. The gas test does not apply to diode sections or to rectifiers.
  2. Set potentiometer L at GM (replaces 60 on dial).
  3. Set the MICROMHOS range switch at 3000.
  4. Hold down GAS NO.1 button and adjust potentiometer R until the meter reads 100 micro ohms on the 0-3000 scale.
  5. While holding down GAS NO.1 button, press GAS NO.2 button. If the pointer moves upward more than one scale division, the tube contains too much gas for satisfactory operation. If the pointer movement is less than one scale division, the tube can be considered sufficiently free from gas.

NOTE: If the pointer cannot be brought down to 100 micro ohms by adjusting the potentiometer R with the GAS NO.1 button pressed, set R at 82, note the position of the pointer, and press GAS NO.2 button to see if the pointer moves upward more than one scale division. In some cases it may be necessary to let the tube warm up for a few minutes before making the gas test, since the tubes may develop gas only after filament current has been on for a period of time.

VI - NOISE TEST

This procedure detects intermittent contacts between tube electrodes during the shorts test, even though the shorts are too brief to be detected by the neon shorts lamp.

  1. After completing the conventional shorts test explained above, connect the NOISE TEST jacks on the panel of the I-177 tube tester to the antenna and ground terminals of a radio receiver.
  2. With the radio receiver turned on, with the volume advanced, and with the tube tester still set as in SHORTS TEST section “k” above, tap the tube while turning the SHORT-TUBE TEST switch slowly from position 1 to 5. Loud static noises coming from the loudspeaker of the radio receiver indicate shorts between electrodes, and mean that the tube is ba

NOTE: This procedure was developed long before solid state receivers. There's no way in hell, even if the blocking capacitor in the tube tester IS good, that I'd use a solid state receiver for this test. It's not worth the risk.

VII - TESTING CATHODE-RAY INDICATOR TUBES.

Since the function of these tubes is to indicate rather than amplify, conventional mutual conductance or quality tests cannot be made. Test data is therefore given only for the purpose of checking the functioning of the eye. No shorts tests are made. The meter and controls L, R, and MICROMHOS are not used in this test. The procedure checks only the opening and closing action of the eye.

  1. Turn on the tube tester and adjust the line voltage as outlined above.
  2. Set the FIL switch at the correct filament voltage (2.5 for the 2E5 tube and 6.3 for tybe types starting with 6).
  3. For the 2E5, 6AB5, 6E5, 6G5, 6H5, 6N5, and 6U5 tubes, set selector switch A at 12, set selector switch B at 3, and press the red AMPL.TEST button. The eye should open. Release the button, set selector switch B at 2, and again press the red AMPL.TEST button. The eye should now close if the tube is goo
  4. For 6AD6 and 6AF6 tubes, set selector switch B at 8, set selector switch A at 2, and press the red AMPL.TEST button. Eye No.1 should open and eye No.2 should close. Release the button, set selector switch A at 3 and again press the AMPL.TEST button. Eye No.2 should open and eye No.1 should close if the tube is goo

I-177 instructions is from I-177 beta 1.08 worksheet, from July 5, 2002. A great compilation by Nolam E. Lee.
Cape Old Radio ©Carlos Eduardo Lazarini da Fonseca