Eberline ESP-1 - Page 63

If the counter has failed, check:
(1) High voltage at the detector connector. Use a voltmeter with 1000 МО or greater input
impedance. The voltage should be set for the detector being used. If not correct, see
"Repairing the High Voltage Supply," section V.C.2.d. before proceeding.
(2) Amplifier output at pin 7 of A103 using an oscilloscope with an Eberline MP-2 (or
MP-1) connected to the detector connector. Set the pulser to 15 mV and 40k counts per
minute.
The positive pulse on the scope should be 2.0 volts or greater. If good, go to step 3 below.
If bad, the probable causes are:
(a) A103 inoperative.
(b) Q106 inoperative.
(c) CR103 shorted.
(d) C11 defective.
(3) Discriminator output at pin 10 of A103 using the scope (MP-2 still connected and set
as in step 2 above). This should be a positive square pulse of 4.0 volts or greater. If good,
go to step 4 below.
If bad, the probable causes are:
(a) A103 inoperative.
(b) DISCR control (R16) defective.
(c) A105 inoperative.
(4) Binary output at pin 9 of A105 using the scope (MP-2 still connected and set as in step
2 above). This signal should change state at the rate of the MP-2 and switch between
ground and 4.0 volts or greater.
If the signal is not present, A105 is bad. If the signal is present, move the scope to pin 14
of A1 (microcomputer chip). The signal should be as above. If it is, A1 is bad. If not, check
for broken wire in the ribbon jumper between boards, for damaged PC board, or bad
contact at A1, pin 14.
If the counter is noisy, the most common causes of counter noise are:
(a) High voltage too high.
(b) Loose or bad ground connections.
ESP1.MAN/February 1992