This service manual of the old video cassette recorder VT-LC50EM is very good readable even the tiniest numbers (i.e. IC-pins). The circuits are very clear. Many details of the schematic are very good described but in GERMAN language. Many schematic details - but complete at all. Common background information of several details are enclosed and physical knowledge of the TFT liquid crystal display for example. The manual lacks PCB drawings. If you understand german I would recommend this manual for you.
Text excerpt from page 83 (click to view)
THE AUDIO CAN NOT RECORD
NO Is bias level at L101 OK? YES
In starting recording, is there sine wave at pin 11 of IC101? YES
Check POWER BLOCK and voltage of base of Q103.
Check disconnection and short of L101.
Is there audio signal at pin 76, 78 and 80 of IC101? YES
Check IC701 and the circuit from TUNER or audio input jack to IC701 .