I have a Nakamichi PA7 which goes immediately into protection, pulling well in excess of 1.75A. There is a "buzzing" sound (relays?) which accompanies this.
I have replaced the low value electrolytics on the PCBs, and have added (and now removed) the additional capacitance across c102/c202 which has been suggested.
The outputs all seem fine on multimeter testing, and I am wondering how I can "cold bias" the amp to try and test
any assistance appreciated
Peter
I have replaced the low value electrolytics on the PCBs, and have added (and now removed) the additional capacitance across c102/c202 which has been suggested.
The outputs all seem fine on multimeter testing, and I am wondering how I can "cold bias" the amp to try and test
any assistance appreciated
Peter
That amount of current must suggest a heavy current device is faulty at or near the output but you say the outputs are "okay " otherwise you have a short circuit somewhere and if that is in a low current device it should be obvious .
And you say you have tested the higher value capacitance's--?
It would be harder to find if it was just "chattering " safety relays but it goes straight into safety due to the tested high current, that should be easier to trace simply by isolating various parts of the circuit from the power lines to see if the high current drops then check the isolated part doing it in stages .
I still think its somewhere near the output rather than the low current input.
And you say you have tested the higher value capacitance's--?
It would be harder to find if it was just "chattering " safety relays but it goes straight into safety due to the tested high current, that should be easier to trace simply by isolating various parts of the circuit from the power lines to see if the high current drops then check the isolated part doing it in stages .
I still think its somewhere near the output rather than the low current input.
Thanks Duncan.
My faithful Peak ESR70 capacitance meter has died, so I have replacement coming and will report back. I did measure the large caps originally and from memory they were between 29k and 33k, but I will check this when the new ESR70 arrives.
I concur that it must be something on the "heavy current" side. Given that it appears to be both channels, that implies the current limiter, protection or power supply-so I will disconnect each amp board and see what results
I will report back
My faithful Peak ESR70 capacitance meter has died, so I have replacement coming and will report back. I did measure the large caps originally and from memory they were between 29k and 33k, but I will check this when the new ESR70 arrives.
I concur that it must be something on the "heavy current" side. Given that it appears to be both channels, that implies the current limiter, protection or power supply-so I will disconnect each amp board and see what results
I will report back
