Multitone RPR750 Series - Basic Test Measurements; MKI Decoder 0261-7498 Underside; MKII Decoder 0261-8243 Underside

TM1215 Iss. 6.0 RPR750
MKI Decoder 0261-7498 Underside
MKII Decoder 0261-8243 Underside
4.5.4 Basic Test Measurements
1. 3.3V ±5% should be present on the positive end of C12.
Fault condition found - check the operation of the voltage converter IC10, the series
inductor L1, or the rectifier diode D29. With a 'scope probe on IC10 Pin 1, check for the
converter oscillating; a short circuit on the 3.3V rail would prevent this from working.
2. 3.3V ±5% should be present on the Source pin of TR10.
Fault condition found - check the "battery detect" circuit, TR8, R10 & C62, or for a short
circuit elsewhere on the 3.3V supply rail.
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