Dear All,
I have a Accuphase P102 that I recently purchased, unfortunately there were some bad soldering points, that has been taken care of, but now one of the power transistors went up in smoke... anybody any idea how this could happen? Bias is measured at 200mv seems a little high!
Does anybody know what the bias should be?
Does anybody know if there is a service manual available?
thanks so in advance for your help!
with regards
Joris
the Netherlands
I have a Accuphase P102 that I recently purchased, unfortunately there were some bad soldering points, that has been taken care of, but now one of the power transistors went up in smoke... anybody any idea how this could happen? Bias is measured at 200mv seems a little high!
Does anybody know what the bias should be?
Does anybody know if there is a service manual available?
thanks so in advance for your help!
with regards
Joris
the Netherlands
Hi Joris,
There is a circuit diagram here: https://www.diyaudio.com/community/threads/accuphase-p-102-schematic.363147/post-6422895
Service manual will be trickyer..
I wouldn't fiddle with the bias prior to find what's wrong. 200mV might be correct. Start looking for bad driver transistors and compare parts with the good channel.
Good luck,
Hugo
There is a circuit diagram here: https://www.diyaudio.com/community/threads/accuphase-p-102-schematic.363147/post-6422895
Service manual will be trickyer..
I wouldn't fiddle with the bias prior to find what's wrong. 200mV might be correct. Start looking for bad driver transistors and compare parts with the good channel.
Good luck,
Hugo
Have a look at https://files.fm/u/erjxzb4bj
The P102 is not listed but another amp from the P-series might resemble it.
Hugo
The P102 is not listed but another amp from the P-series might resemble it.
Hugo
Hello again, terrible silence on this topic 
There is hope that I will get the BIAS value but I have to wait.
However, I came up with another way. The documentation states that the power consumption (without signal output) is 245 W. So I need to set the BIAS so that the amplifier consumes just these 245 W.
Can someone who knows this confirm if I'm thinking correctly?
Regards
Tom
There is hope that I will get the BIAS value but I have to wait.
However, I came up with another way. The documentation states that the power consumption (without signal output) is 245 W. So I need to set the BIAS so that the amplifier consumes just these 245 W.
Can someone who knows this confirm if I'm thinking correctly?
Regards
Tom
Supply voltage + total consumption + value of resistances at the measuring points divided by the number of modules = bias value at first glance.
otherwise, you know that at 14mV it works, that at 22mV it does not burn out, at 18mV you should remain safe and you can compare with the total consumption of the device without an incoming signal.
otherwise, you know that at 14mV it works, that at 22mV it does not burn out, at 18mV you should remain safe and you can compare with the total consumption of the device without an incoming signal.
Today I played with the BIAS adjustment. At the previously set 15 mV, the amplifier consumed 95 W. I slowly increased the BIAS value by measuring the temperature and power consumption.
At 87 mV, the amplifier consumes 210 W (without signal output) and the heatsink temperature is 50 degrees C. I left this value and after an hour of normal music listening, the temperature increased to 58 degrees C.
The first impression is more sound in the sound. Everything sounds more fully.
Regards
At 87 mV, the amplifier consumes 210 W (without signal output) and the heatsink temperature is 50 degrees C. I left this value and after an hour of normal music listening, the temperature increased to 58 degrees C.
The first impression is more sound in the sound. Everything sounds more fully.
Regards
https://www.diyaudio.com/community/threads/transistor-dissipation-and-turbo-projects.234153/
C3181 in da Accu ,btw baby sitter silent fan is good in summer
C3181 in da Accu ,btw baby sitter silent fan is good in summer
Attachments
N. Pass again:
"The limits are generally the temperature of the junction,
which you can infer from the known wattage and the
temperature of the case.
Typically the limit is 150 deg C, and the thermal resistance
from junction to case is maybe 1 deg C/watt, so the limit
for a device with a case temperature at 100 deg C is
about 50 watts."
"The limits are generally the temperature of the junction,
which you can infer from the known wattage and the
temperature of the case.
Typically the limit is 150 deg C, and the thermal resistance
from junction to case is maybe 1 deg C/watt, so the limit
for a device with a case temperature at 100 deg C is
about 50 watts."