Yamaha n8 Service Manual page 134

n8/n12
2. Checking A/D input
ADI1 to ADI14
Each point of ADI1 to ADI14 has 2 test lands and their phases are opposite to each other while the signal level is the same.
The signal fl uctuates based on the bias voltage of approximately 2.5 V on the test lands.
The signal does not fl uctuate normally if the voltage, especially, +15 VA, or -15 VA is not normal.
Check the analog signal with reference to TL260 (AGND).
* Full-scale input of the A/D converter is 2.9 Vp-p (typ).
TL223
TL236
ADI15 (n12 only)
A signal which is created by increasing the sound signal from the microphone for talkback by approximately 40 dB is detected at
ADI15 regardless of the TALKBACK ON/OFF setting on front panel.
The signal fl uctuates based on the bias voltage of approximately 2.5 V on the test lands.
The signal does not fl uctuate normally if the voltage, especially, +1.5V, +15 VA, or -15 VA is not normal.
Check the analog signal with reference to TL260 (AGND).
* Full-scale input of the A/D converter is 3.0 Vp-p (typ).
134
TL204
TL219
TL224 TL221 TL220
TL222
TL235 TL233 TL227
TL234
TL207
TL206
TL217 TL215 TL213
TL218 TL216 TL214
TL225 TL231
TL228 TL226 TL232
TL237
TL260
TL205
TL259
TL208
TL211 TL209
TL212 TL210
TL229
TL230