Hello.
Integrated amplifier MARANTZ PM 700 DC.
Left channel no problems BIAS adjust 14 mV.
Right channel distorted and impossible adjust BIAS......1.5.......1.6 mV max.
1v DC voltage on right speaker terminal.
Trimmer is ok .
All voltages are OK
Thank you
SM.
https://www.google.com/url?sa=t&sou...8QFnoECAgQAQ&usg=AOvVaw1Zn33xMt46LyUGVnLXXf_j
Integrated amplifier MARANTZ PM 700 DC.
Left channel no problems BIAS adjust 14 mV.
Right channel distorted and impossible adjust BIAS......1.5.......1.6 mV max.
1v DC voltage on right speaker terminal.
Trimmer is ok .
All voltages are OK
Thank you
SM.
https://www.google.com/url?sa=t&sou...8QFnoECAgQAQ&usg=AOvVaw1Zn33xMt46LyUGVnLXXf_j
If I turn up the volume too much, the amp goes into protection. I even replaced both output transistors on the right channel, but no change.
Measure voltage at Q718b (+2.1Vdc) and Q720b (-2.1V). Also measure volt drop
across diode pair Q744 (1.3V?) possibly one has failed short? Adjusting trimmer
(R742) should cause Q718b voltage to rise/fall...
"All voltages OK" with "1V on spkr terminal" ???
across diode pair Q744 (1.3V?) possibly one has failed short? Adjusting trimmer
(R742) should cause Q718b voltage to rise/fall...
"All voltages OK" with "1V on spkr terminal" ???
Q718b...+2,1v
Q720b....-1.7v
Adjusting trimmer
(R742) should cause Q718b voltage to rise/fall....... works
Diod Q746 was dead,I replaced with 4148.
After replacing no change
Q720b....-1.7v
Adjusting trimmer
(R742) should cause Q718b voltage to rise/fall....... works
Diod Q746 was dead,I replaced with 4148.
After replacing no change
Check R760, R762(33ohms) on base of outputs, also emitter resistors R764, R766.
Diode test outputs Q726 b-e junction, likewise Q728b-e
Diode test outputs Q726 b-e junction, likewise Q728b-e
Emitter resistors R764, R766 will be ok since Q720b at -1.7V.
Expect one of the following to be open, R760, R762, Q726b-e, Q728b-e
Expect one of the following to be open, R760, R762, Q726b-e, Q728b-e