hello there!
just recently i cleaned and recapped my inherited marantz 2270.
everything seems to work just fine, i sounds just great..
except that the speaker protection relais does not react propperly.
as i replaced the caps (with same uF-ratings but slightly higher V-ratings) on the power supply board -which seem to define the timing of the relais- i do not know how to fix this. i just dont have enough background to do the maths.
could someone please help me find a clue and or solution?
thanks in advance
just recently i cleaned and recapped my inherited marantz 2270.
everything seems to work just fine, i sounds just great..
except that the speaker protection relais does not react propperly.
as i replaced the caps (with same uF-ratings but slightly higher V-ratings) on the power supply board -which seem to define the timing of the relais- i do not know how to fix this. i just dont have enough background to do the maths.
could someone please help me find a clue and or solution?
thanks in advance
Attachments
Sadly I don't know the math either however...
Looks like R816(390K) and C807(220uf/16V) form the RC timer for power-ON mute.
Increasing the voltage rating of the cap does not affect this timer. I suspect
that we are not interested in fully charging C807 but more interested in the
time taken for it to reach (about) 1.25V signalling H809, H810 being turned on
and current flow through the relay coil.
This mute period is to allow startup transients to settle. If your amp has
problems then these transients may continue beyond the mute period, the protection
circuit will detect this excessive dc voltage and delay operating the relay until
the transients settle, that is, the relay is not being opperated because of
excessive Vdc, not a failure in the RC mute timer.
Suggest monitor the dc voltage at pins J813 and J814 to GND during power up. If both
voltages are below 100mV and the relay does not operate then there is a timer issue
maybe C806 leakage or ...
Looks like R816(390K) and C807(220uf/16V) form the RC timer for power-ON mute.
Increasing the voltage rating of the cap does not affect this timer. I suspect
that we are not interested in fully charging C807 but more interested in the
time taken for it to reach (about) 1.25V signalling H809, H810 being turned on
and current flow through the relay coil.
This mute period is to allow startup transients to settle. If your amp has
problems then these transients may continue beyond the mute period, the protection
circuit will detect this excessive dc voltage and delay operating the relay until
the transients settle, that is, the relay is not being opperated because of
excessive Vdc, not a failure in the RC mute timer.
Suggest monitor the dc voltage at pins J813 and J814 to GND during power up. If both
voltages are below 100mV and the relay does not operate then there is a timer issue
maybe C806 leakage or ...
Attachments
hello!
thank you people for the immediate answers, highly appreciated.
voltage at pins J813 and J814 to GND during power up is all over the place and settles at around 5mV.
replacing c807 to the part that has been installed previously didnt change anything (but i dont know if it is faulty) so i will try a brand new one, once i ordered it.
relais seems to actuate immediately after power up, so no muting time at all. resulting in a pop sound and a lf-wobble below 10hz..
🙁
thank you people for the immediate answers, highly appreciated.
voltage at pins J813 and J814 to GND during power up is all over the place and settles at around 5mV.
replacing c807 to the part that has been installed previously didnt change anything (but i dont know if it is faulty) so i will try a brand new one, once i ordered it.
relais seems to actuate immediately after power up, so no muting time at all. resulting in a pop sound and a lf-wobble below 10hz..
🙁