Electrical Checkout Procedures; General Information; Test Procedures; Standard Initial Conditions - Crown Com-Tech CT-1610 Service Manual

Rev. 0
6 Electrical Checkout
Procedures

6.1 General Information

The following test procedures are to be used to verify
operation of this amplifier. DO NOT connect a load or
inject a signal unless directed to do so by the proce-
dure. These tests, though meant for verification and
alignment of the amplifier, may also be very helpful in
troubleshooting. For best results, tests should be per-
formed in order.
All tests assume that AC power is from a regulated
source. Test equipment includes an oscilloscope, a
DMM, a signal generator, loads, and I.M.D. and T.H.D.
noise test equipment.

6.2 Test Procedures

6.2.1 Standard Initial Conditions

Level controls fully clockwise.
Stereo/Mono switch in Stereo.
Sensitivity switch in 26 dB fixed gain position.
70-V mode switches in the 8/4 ohm position.
Place a jumper across pins 3 and 4 of both TP100 and
TP200. This will keep the amplifier out of auto standby.
It is assumed, in each step, that conditions of the am-
plifier are per these initial conditions unless otherwise
specified.

6.2.2 Turn On Delay

Spec: 4 seconds ±2 seconds.
Procedure: Up to 1 second after turn-on, the current
path to the primary is through an NTC. After 1 second
a relay closes that shorts out the NTC. Three seconds
later bias is applied to the output section of the ampli-
fier.

6.2.3 Output Bias Adjustment

Spec: 320 to 340 mVDC.
Procedure: While the heatsink temperature is less than
Com-Tech 810 and 1610 Amplifier Service Manual
40° C measure the DC voltage on the output module
across R37 (15 ohm), adjust R02 if necessary. Mea-
sure the DC voltage on the output module across R39
(15 ohm), adjust R33 if necessary. Repeat for the sec-
ond channel.

6.2.4 ODEP Voltage Adjustment

Spec: See chart
Procedure: Measure the heatsink temperature. If un-
able to do so, note the room temperature and do this
procedure while the heatsink temperature is still at room
temperature.
Measure the voltage on TP100-5 and adjust R186 for
the voltage per the chart. This voltage will be a nega-
tive voltage. Measure the voltage on TP100-10 and
adjust R300 for the voltage per the chart. This voltage
will be a positive voltage. For channel 2 the designa-
tions are TP200-5, TP200-10, R286, and R400.
ODEP Voltage Chart
Tolerance ±0.1V
°F °C
66 18.9
68 20.0
70 21.1
72 22.2
74 23.3
76 24.4
78 25.6
80 26.7
82 27.8
84 28.9
86 30.0
88 31.1
90 32.2
92 33.3
94 34.4

6.2.5 DC Offset

Spec: 0 VDC, ±10 mV.
Procedure: Measure DC voltage at the output con-
nectors (rear panel). There is no adjustment for output
offset. If spec is not met, there is an electrical mal-
function. Slightly out of spec measurement is usually
due to U104/U204 out of tolorance.
]
Voltage
10.55
10.48
10.41
10.34
10.26
10.19
10.12
10.05
9.97
9.90
9.83
9.75
9.68
9.61
9.54
6-1