Shure Pro Master 700 Service Manual page 26

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NOTE: The Interchange" footnotes shown below
the connector tables in the circuit diagrams are for manu-
facturing purposes only. Wires should not be interchanged
during servicing as incorrect ohmmeter readings may
result.
TROUBLESHOOTING
A general troubleshooting process is as follows: If the
console is completely "dead," check the ac power source,
fuses, chassis power supply output (54V across capacitors
C5 and C6), regulated power supply (+15V between pin E
and ground, connector P502, or -15V between pin M and
ground, P503, board A5). If the POWER LED is on but the
output is low or not present, follow the procedure de-
scribed under TROUBLESHOOTING in this manual. Fol-
lowing localization of the problem, determine that the
input and output voltage to the board is correct. If an incor-
rect voltage is found, perform Ac and Dc Voltage Measure-
ments as described below to isolate the problem area.
AC VOLTAGE MEASUREMENTS
The numbers within rectangular symbols
circuit diagrams denote the ac voltages at that point under
the following test conditions:
1. Voltages measured with respect to chassis unless
otherwise indicated.
2. Line voltage: 120V, 60 Hz.
3. Test signal of 0.5 mV, 1 kHz applied across pins 2 and
3 of connector J802.
4. Ac voltage measurements may vary +30% from
values shown.
5. Measurements made with ac VTVM of 1 megohm or
greater input impedance.
6. No load on SPEAKER OUTPUTS jacks (J16-J19).
7. All controls in full clockwise settings.
8. REVERB RETURN set to full counterclockwise.
9. PAN (700) and EQ controls set to center.
DC VOLTAGE MEASUREMENTS
The numbers within elliptical symbols
cuit diagrams denote the dc voltages at that point under
the following test conditions:
1. Voltages measured with respect to chassis unless
otherwise indicated.
2. Line voltage: 120V, 60 Hz.
3. No input signal applied.
4. Dc voltage measurements may vary +20%
values shown.
5. Measurements made with VTVM of 11 megohms or
greater input impedance.
RESISTANCE MEASUREMENTS
With the ac line cord disconnected from the ac source
on the
and the Power ONIOFF switch in the OFF position, the
following ohmmeter measurements may be made:
1. Reverb pan A10 output coil: approximately 360 ohms;
input: approximately 40 ohms.
2. Transformers may be checked for continuity of each
winding.
3. To test transistors and diodes, refer to the section on
ACTIVE COMPONENT CHECKING.
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