Bose 1600-VI Service Manual download pdf (Page 32)

32

TEST PROCEDURES

3. Distortion Level

3.1 Apply a 1.5 Vrms, 1 kHz signal for low

sensitivity units, or a 775 mVrms, 1 kHz

signal for high sensitivity units, to the

amplifier channel under test.

3.2 Set the CH1 or CH2 level controls, as

appropriate, to the full on position (fully

clockwise).

3.3 Measure the distortion level. It should

be ≤ .2% THD.

4. DC Offset

4.1 With no signal applied, measure the

DC voltage level at the amplifier output.

4.2 It should be ≤ 35 mVdc.

5. Overcurrent Shut Down Test

5.1 Apply a 1.0 Vrms, 1 kHz signal to the

amplifier channel under test.

5.2 Use a 0.1 Ω, 50 W resistor to simulate

a short circuit across the amplifier channel

under test. Do not apply a dead short

across the amplifier output as damage

could result. Test duration should be ap-

proximately 5 seconds.

5.3 The amplifier protection circuit should

cause the output relays to drop out, remov-

ing the output signal from the binding

posts. After a short period, the amplifier

should attempt to come out of protect

mode. If the short is still applied, the ampli-

fier should stay in protect mode.

Once the short is removed, the output

relays should stay on and provide signal

output to the binding posts.

6. Thermal Shut Down Test

6.1 Remove the top cover using Disassem-

bly/Assembly procedure 1.

6.2 Apply a 16 mVrms, 1 kHz signal to the

input jacks of both channels of the amplifier

under test.

6.3 On the amplifier PCB, locate RT100

and RT200. They are located near the

corners of the PCB. See the amplifier PCB

layout diagram for more information.

6.4 Apply a short to RT100. Verify that the

appropriate protection LED for CH 1 illumi-

nates on the front panel and that the fan

speed increases while RT100 is shorted.

6.5 Remove the short on RT100.

6.6 Apply a short to RT200. Verify that the

appropriate protection LED for CH 2 illumi-

nates on the front panel and that the fan

speed increases while RT200 is shorted.

6.7 Remove the short on RT200 and

replace the top cover using Disassembly/

Assembly procedure 2.

7. Channel Imbalance Test

7.1 Apply a 775 mVrms, 1 kHz signal to

both channels of the amplifier under test.

7.2 With both gain pots on the front panel

fully CW, reference a dB meter to the

output level of one channel.

7.3 Measure the output level on the other

channel of the amplifier. There should be

less than a 0.5 dB difference between

channels.

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