Eico 667 Instruction Manual

Page 1

INSTRUCTION MANUAL

Page 2

MODEL 667 ADDENDUM - TRANSISTOR

(For Instruction Manual)

An Improved procedure has been developed for transistor testing, which is described in the
following revision of steps 5 to 8 on page 7 of the Instruction Manual. No transistor chart is
provided, as it is not required when using the revised test procedure. m of
transistors now available, a transistor handbook would be needed, in any case, to determine the
type (p-n-p or n-p-n) and basing of all the transistors to be encountered.

Revised Steps 5 to 8, Page 7 of the INSTRUCTION MANUAL:

5. Refer to a transistor handbook for the type (p-n-p or n-p-n) and basing of the transistor to be
tested. Note that only signal transistors can be tested with the instrument and the criteria
described below apply only to signaI transistors (not power transistors).

6. Insert the emitter (E), base (B), and collector (C) lead of the transistor in the corresponding
terminals of the transistor socket located immediately above the TRANSISTOR TEST selector.

7. Turn the TRANSISTOR TEST selector From "TUBIE'l to position I (first position away from "TUBE')
on the p-n-p or n-p-n side depending on the type of transistor under test. The indication on
the meter will be proportional to the collector current with emitter grounded and no base
signal. On this test, transistors in good condition should preferably read in the loo GOOD'
area between 0 and 40 on the 0 to I40 meter scale, but are acceptable with readings up to 80
on this scale. Reject transistor that reads above 80 on this test.

8. Turn the TRANSISTOR TEST selector to position 2 (second position away from lTUBE"), and
read the DC Beta (ratio of collector current to base current). The minimum acceptable DC
Beta reading depends on the [co reading obtained in step 7. The higher the Ico reading (up to
the maximum acceptable limit of 80), the higher the minimum acceptable DC Beta reading is,
in direct proportion, Numerically, the minimum acceptable DC Beta reading is slightly more
than 60% of the Ico reading on the 0 to I40 meter scale. Examples: If the Ico scale reading
is 80, the minimum acceptable DC Beta reading is 50; if the Ico scale reading is 40, the minimum
acceptable DC Beta reading is 25.

Page 9 of the INSTRUCTION MANUAL:
Delete the following material from the text:
"In some cases, the range of Beta given in the chart has been taken directly from the

transistor manufacturer's specification; in other cases Beta has been calculated from the
grounded base Alpha, Alpha ce, according to the relationship:

Alpha ce
I-Alpha ce

Beta =