Good value for money. This also serves the Yamaha TC-511B which just has a different front panel from the TC-511S. This appears to be the complete Yamaha factory service manual. It has useful descriptions of the signal paths through the unit and the names of the major functional blocks. The accompanying circuit diagrams are useful. It's good enough on how to pull the unit apart. The section on how to adjust the recording head bias was not particularly helpful. You are better off recording pure tones of various frequencies for a range of bias settings, playing them back and selecting the bias setting which gives the overall flattest frequency response for its respective channel.