fiuch that it, too? is biased just beyond cut-off. Under these conditions, no
plate current flows in the 6BN8 and no reading is obtained on the meter in
its plate circuit.
However, if the tube under test is gaseous, or its grid is contaminate<i with
some of the cathode coating, then current will flow from grid to plate and
through the 5.6 meg resistor back to the grid again. This will produce aposi*
live voltage drop across the 5,6 meg resistor, lifting the cut-off bias on the
6BN8 and producing ameter deflection. Upon seeing this deflection, the
technician immediately knows that the test tube is defective and areplacement
is indicated.
HOW TO OPERATE THE DYNA JET MODEL 600 TUBE TESTER
Simplified Instructions
1. Look up tube in chart
2. Set Heater to voltage indicated in Heater column of chart.
3. Set “A**, "B” and “C" controls to positions indicated on chart.
4. Insert tube into proper socket as indicated on chart.
5. Allow tube to warm up and observe Shorts indicator. If Shorts light
glows, reject tube.
6. Depress Grid Emission button. Any deflection of the meter pointer
into the “Grid Emission-Reject" area of the scale is cause for reject
of the tube.
7. Depress Quality button. Tube will read on the Good-Bad scale of
the meter.
8. To test for all other shorts rotate Switch through each of its
positions and observe Shorts lamp. (The Shorts lamp may glow
instantaneously while rotating switch “C” through ita position. This
is due to acapacitor discharge and is to be ignored.)
TEST PROCEDURE
I
The Model 606 Tube Tester is designed for use at 105^125 volts, 50*60 cycle
A.C. only. The instrument is turned on and ready for use merely by inserting
the line cord into an A.C, socket. The first step in the testing of atube is to
look up this tube in the chart contained in the cover of the instrument. Let us
take atypical example such as a6AU6. Fig. 7shows atypical listing for this
type. The heater voltage for this tube type is 6, as shown, and the heater
switch must therefore be set to the 6voH position. This will then apply the
correct heater voltage to the tube under test.
1^" __ »wter "A" ^^Socket Ne.
6AU6 633 S11
Figure 7.
If the tube in question had a17 volt heater, the heater switch will be
rotat^ to the 15-20 position. Any tube with a heater voltage between 15-20
volts is tested with the heater switch in this position,
CAUTION! THE HEATER SWITCH MUST BE SET TO THE COR-
RECT FILAMENT VOLTAGE BEFORE INSERTING THE TUBE IN
THE SOCKET. FAILURE TO OBSERVE THIS PRECAUTION MAY
RESULT IN BURNING OUT THE FILAMENT OF THE TUBE.
'“set to 33, the "B” switch placed in position 6, and the
"C switch in position 1, The tube is now inserted into socket No. 1, as shown
mthe last column of the type UsUng in Fig. 7. The tube is automatically tested
for grid to cathode shorts and leakage as soon as the tube is inserted into
the socket
To test for grid emission, depress the Grid Emission button. Any deflection
of the meter pointer into the “grid emission*reject“ area of the meter scale
indicates adefective tube. This tube should be discarded. If the tube passes
the Grid Emission test, we then proceed to the Quality test.
The tube is tested for Quality by depressing the Quality button and observing
the Good-Bad reading on the meter scale. Afew tube types do not normally
register ameter reading mto the “Good” area because of our exceptionally
critical Quah^ test. For these types the chart indicates the minimum
numencal reading that this tube must have to be acceptable.
The tube can be tested for shorts or leakage between any of the other
elements by rotating switch “C” through each of its positions. If the Shorts
indicator neon lamp glows in any of the switch positions of switch “C” the
tube should be rejected. (As the switch is rotated from one position to the next
shorts indicator may instantaneously glow due to acapacitor discharge'
Inis 13 to be ignored.)
C3U rJT ^1^TJiuitJOLiun lor agiven element,
therefore the Short mdicator lamp may normally glow in certain positions of
Switch C.even if fhexe is no short in the tube. The chart will indicate where
^normal short indication will occur. These tubes should not be rejected
for these normal shorts. ^
This completes the test on the tube.
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