Checking Of Protection Information - Yamaha A-S701 Service Manual

A-S701
Diode THM protection
Cause: Abnormal temperature of diode (D111 of MAIN (1) P.C.B).
Normal value: 0 to 0.346V (AD value: 0-18)
Detection port: THM3 (FUNCTION (1) P.C.B. 97 pin of the microprocessor IC502)
Detected at: THM3 (TH501 of FUNCTION (4) P.C.B., D111 of MAIN (1) P.C.B.)

• Checking of protection information

Check the following information when a protection function has been activated.
・ Protection history (up to 4)
・ Position of "VOLUME" knob when the protection function was activated (*)
・ AD value when the protection function was activated
・ AD value when the diode THM protection function was activated
・ Operating information for the speaker relay/headphones relay
・ AD value for the "BALANCE" knob
・ Input source information
Since the "VOLUME" knob automatically moves to the position when the protection function was activated, do not
*
to operate any other knob while the "VOLUME" knob is moving.
If several protection functions have been activated, history for up to four of the most recent protection functions can be
viewed by turning the knob indicated below.
BASS: History for the most recent protection function
TREBLE: History for the 2nd most recent protection function
BALANCE: History for the 3rd most recent protection function
LOUDNESS: History for the 4th most recent protection function
* When the "BASS" or "TREBLE" knob is turned to "–" or the "BALANCE" knob is turned to "L", the corresponding protection history will
be indicated by the power indicator.
* When the "LOUDNESS" knob is turned to a position halfway between "FLAT" and "-30dB", the 4th most recent protection history will be
indicated.
* When the "BASS", "TREBLE" and "BALANCE" knobs are set to their top positions and the "LOUDNESS" knob is set to "FLAT", the most
recent protection function (the same as that indicated by turning the "BASS" knob) is indicated by the "
the "VOLUME" knob will not move at this time. The "VOLUME" knob will move if a protection history is selected with one of the knobs.
(Fig. 7)
* The order of priority for indicating the protection history is as follows:
BASS > TREBLE > BALANCE > LOUDNESS.
If the "TREBLE" and "BALANCE" knobs were turned at the same time, the "TREBLE" knob will have priority, and the 2nd most recent
protection function is indicated.
When the 4th most recent protection function is indicated
18
* When the "LOUDNESS" knob is turned to a
position halfway between "FLAT" and "-30dB",
the 4th most recent protection history will be
indicated.
Note:
When checking the protection history, the "VOLUME"
knob will automatically move to the position when
the protection function was activated. Do not operate
any other knob while the "VOLUME" knob is moving.
Fig. 7
" (power) indicator. However,
z