Arp omni field change notice model 2483

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FCN0011

FIELD CHANGE NOTICE

0 MODEL: OMNI 2483 DATE: 11/14/77

EFFECTIVITY: SEE BELOW
EST. TIME TO COMPLETE: 20 min.

Please make the following changes to any OMNI that is being repaired for a
series 'A CMOS failure. (This Field Change Notice is not necessary for OMle containing
series '8' devices.)

REASON FOR CHANGE:

To reduce the possibility of transient noise from power supply affecting the
reliability of the CMOS circuitry when instrument is turned on or off.

MATERIAL REQUIRED:

QTY. DESCRIPTION ARP PART NO.
1 68K 5% res. 1000321
2 .0I ceramic disc cap. 1100151
2 U2314 Transient Suppression 1201501
in WA

PARTS DISPOSTION:
Order FCN0011 parts kit.

DETAILS OF CHANGE:

Refer to the following page (Sht. 2) and add the components as illustrated.
Refer to location of components on P.C. Board assembly (Sht. 3).

Power Supply trimmer, R19, should be turned fully counterclockwise before
turning instrument on after the zener diode installation; then readjust Power
Suppy to plus and minus 13.00 volts.

It is recommended that defective CMOS devices be replaced with '3'
series where possible.

ARP INSTRUMENTS INC., 45 HARTWELL AVENUE, LEXINGTON, MA 02173 (617) 861-6000