Arcam PA240, Service Manual

Page: 10 / 60

EN-10
Functional Verification and Test Procedure
1. Check mains power consumption at idle (no inputs or loads connected)
Mode should be set to ST.
Input should be set to RCA.
Gain should be set to 31dB.
Expect to see 60 – 70W @ 230V.
2. Set bias to approx. 9mV if cold, 12mV when hot.
3. Check DC offsets at speaker terminals with DVM (no inputs or loads connected)
Should be < 10mV, typically 5mV.
Repeat for other channel.
4. Check residual noise floor (no inputs connected)
8R load – balanced feed to analyser input.
10-500kHz input filter, amplitude should be < 300uV, typically 250uV
10-22kHz input filter, amplitude should be < 110uV, typically 90uV
10-22kHz A weighted input filter, amplitude should be < 90uV, typically 70uV
Repeat for other channel.
5. Check THD into 8R (RCA input)
8R load – balanced feed to analyser input.
Generator output to 1kHz, level to get approx. 19V output, typically 1.4-1.5V into one channel.
10-22kHz input filter, THD should be < 0.001%, typically 0.0006%.
Repeat for other channel.
6. Check THD into 8R (XLR input)
8R load – balanced feed to analyser input.
Switch to XLR input with rear panel switch.
Generator output to 1kHz, level to get approx. 19V output, typically 2.8-3V into one channel.
10-22kHz input filter, THD should be < 0.001%, typically 0.0006%.
Repeat for other channel.
7. Check THD into 4R (XLR input)
4R load – balanced feed to analyser input.
Generator output to 1kHz, level to get approx. 19V output, typically 2.8-3V into one channel.
10-22kHz input filter, THD should be < 0.0012%, typically 0.0007%
Repeat for other channel.
8. Check dual mono operation
Connect only left XLR input
Switch to Dual Mono mode with rear panel switch.
Generator output to 1kHz, level to get approx. 19V output, typically 2.8-3V into one channel.
10-22kHz input filter, THD should be < 0.0012%, typically 0.0007% on left channel.
Check right channel matches left channel.
9. Check bridged operation into 8R
Connect only left XLR input
Switch to Bridged mode with rear panel switch.
Connect 8R load across L and R +ve output – balanced feed to analyser input.
Generator output to 1kHz, level 2.8-3V into one channel.
10-22kHz input filter, THD should be < 0.0012%, typically 0.0007%.
Output level should be 42V.
Switch to Stereo mode with rear panel switch.
Connect 8R load normally– balanced feed to analyser input.
10. Check maximum output level into 8R
8R load – balanced feed to analyser input.
Generator output level to get approx. 42V output level, this is with all channels driven.
THD should be < 0.01%, typically 0.002%.
Check all other channel.
11. Check maximum output level into 4R
4R load – balanced feed to analyser input.
Generator output level to get approx. 38V output level, this is with all channels driven.
THD should be < 0.01%, typically 0.002%.
Check all other channel.