Service manual

Guide to ASTRO™ Digital Radios
Figure 5.4 A photo illustration which identifies various components which must be replaced or discarded. (Modifications have already been
performed in this example.)
Point 1 is C562. Remove and discard.
Point 2 is VR403. The original part number is 4813830A22—a 9.1V Zener. You must replace it
with 4813830A26—a 13V Zener diode.
Point 3 is R520 (10K). The original part number is 0611077A98. You must replace it with
0611077A74—a 1K chip resistor.
Point 4 is C334 on the RF board. The RF board is accessed under a shield, on the bottom side of
the radio. Remove and discard.
Once these modifications are complete, there are two more tweaks to do. One involves
installing a jumper between pins 2 and 8 of the accessory connector header on the command board.
This completes the normally-closed emergency button switch. Hobbyists have no use for an emergency
button, and without the normally-closed switch installed, the radio will display random “Fail 01/90”
errors upon power-up, and could cause malicious interference to occur on trunking/conventional
systems when emergency beacons are transmitted. Installing this jumper is the equivalent of having the
emergency switch in the “normal” non-activated state.
Figure 5.5 A photo illustration showing pins 2 and 8 jumpered on the ASTRO Digital Spectra™ command board. This completes the normally-
closed emergency button switch, and prevents it from becoming activated. The radio behaves erratically when this switch is left open.