Motorola pro7100 Service Manual download pdf (Page 61)

Maintenance 3-7

3.7 Receiver Troubleshooting Chart

Bad SINAD

Bad 20dB Quieting

No Recovered Audio

START

Audio at pin 8

of U3101?

Check Controller (in the case of no audio).

Or else go to “B”

Ye s

No

Spray or inject 44.85MHz

into XTAL Filter FL3101.

Audio heard?

B

Ye s

No

Check 2nd LO

(44.395MHz) at C3135.

LO present?

B

Ye s

Check volt-

ages on

U3101. OK?

Biasing OK?

No

No

A

Ye s

Check Q3102 bias

for faults.

Replace Q3102.

Go to B

Ye s

No

Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)

Check cir-

cuitry around

U3101.

Replace

U3101 if

defect.

Check circuitry around Y3101.

Replace Y3101 if defect.

1 2 ... 56 57 58 59 60 61 62 63 64 65 66 ... 108 109

Comments to this Manuals

No comments