Hi,
The reading for the Q166 removed out looked normal. The base should read .5 volts. When you soldered it back the base read 1 volts. Looked like Q166 it is leaking voltage to the base. The reading from Q168 were OKAY following the reading in the schematic. Base should read .5 volts and the output should read between 0 and 300mv. To compare the reading can you check and compare the voltages from the Q169 and Q171. Q166 should read same as Q169 and Q168 should read same as Q171.
The reading for the Q166 removed out looked normal. The base should read .5 volts. When you soldered it back the base read 1 volts. Looked like Q166 it is leaking voltage to the base. The reading from Q168 were OKAY following the reading in the schematic. Base should read .5 volts and the output should read between 0 and 300mv. To compare the reading can you check and compare the voltages from the Q169 and Q171. Q166 should read same as Q169 and Q168 should read same as Q171.
Hi,
But the reading for Q168 shown it is OKAY. Also you replaced it with Q175 and it didn't fixed the problem. But the reading of the Q166 are not right. With the Q166 in the base read 1 volts and it is not right. With Q166 out the base read right .4 volts . That it is why before do any else let's compare the reading of Q166/Q168 with a good one.
But the reading for Q168 shown it is OKAY. Also you replaced it with Q175 and it didn't fixed the problem. But the reading of the Q166 are not right. With the Q166 in the base read 1 volts and it is not right. With Q166 out the base read right .4 volts . That it is why before do any else let's compare the reading of Q166/Q168 with a good one.
Hi,
The bases should be about .5volt. When you removed Q166, the base read .4 volts. When soldered it back it read 1 volt. I think when you powered ON the amplifier the system it is looking all the outputs for less than 300mv. More than 300mv means that some thing it is wrong and the system shutdown the power to protect the speakers. That's why to compare the reading with another channel will tell us if we are in the right track. We can do a test to see if it is the Q166. Replace it with Q175 and see what happened with the readings.
The bases should be about .5volt. When you removed Q166, the base read .4 volts. When soldered it back it read 1 volt. I think when you powered ON the amplifier the system it is looking all the outputs for less than 300mv. More than 300mv means that some thing it is wrong and the system shutdown the power to protect the speakers. That's why to compare the reading with another channel will tell us if we are in the right track. We can do a test to see if it is the Q166. Replace it with Q175 and see what happened with the readings.
Q177, 174, 180, 171, all are on the nose
B is -58 or 59 v DC.
C on all is 0.
E is -58 or 59 v DC, (and the ones that have 59 on the B leg have the C as 59 and 58 is 58) Perfect correlation.
Q175 (not in circuit - Its in the 168 location and the original 168 one is sitting in the parts bottle)
B=1.6
C=59
E=0
Q172
B=.6
C=59
E=0
Q178
B=.5
C=59
E=0
Q169
B=.5
C=59
E=0
Q168 has been pulled from circuit, if it was in the amp shuts down)
B=.42
C=.51
E=-59
Q166 (in circuit)
B=1
C=60
E=.7
Q166 Out of circuit
B=.4
C=59
E=.4
I'm stumped - needles to say.
Thanks Tauro.
Srinath.
B is -58 or 59 v DC.
C on all is 0.
E is -58 or 59 v DC, (and the ones that have 59 on the B leg have the C as 59 and 58 is 58) Perfect correlation.
Q175 (not in circuit - Its in the 168 location and the original 168 one is sitting in the parts bottle)
B=1.6
C=59
E=0
Q172
B=.6
C=59
E=0
Q178
B=.5
C=59
E=0
Q169
B=.5
C=59
E=0
Q168 has been pulled from circuit, if it was in the amp shuts down)
B=.42
C=.51
E=-59
Q166 (in circuit)
B=1
C=60
E=.7
Q166 Out of circuit
B=.4
C=59
E=.4
I'm stumped - needles to say.
Thanks Tauro.
Srinath.
Hi,
The problem here it is that the voltages are not too far out of spec and the system do not allowed to do some checks before it shut down the amp.
Let's do one more check. With everything connected check the voltage at the Q167 base,collector and emitter when you power on the amplifier. You may have to power on few times.
The problem here it is that the voltages are not too far out of spec and the system do not allowed to do some checks before it shut down the amp.
Let's do one more check. With everything connected check the voltage at the Q167 base,collector and emitter when you power on the amplifier. You may have to power on few times.
Q168 has been pulled from circuit, if it was in the amp shuts down)
And while powering up it shows these readings.
B=1.2
C=1.5
E=-59
I initially got the below readings for it with it pulled from circuit.
B=.42
C=.51
E=-59
I am confused - what could be happening, I have powered it many many times after that and played it on 1 channel etc etc ... maybe something that regulates it is going ... and letting it get worse and worse ...
Or maybe after many many minutes it will settle back down to the readings I had earlier. Either way, its what I saw ...
Thanks.
Srinath.
And while powering up it shows these readings.
B=1.2
C=1.5
E=-59
I initially got the below readings for it with it pulled from circuit.
B=.42
C=.51
E=-59
I am confused - what could be happening, I have powered it many many times after that and played it on 1 channel etc etc ... maybe something that regulates it is going ... and letting it get worse and worse ...
Or maybe after many many minutes it will settle back down to the readings I had earlier. Either way, its what I saw ...
Thanks.
Srinath.
Hi,
Does the display worked?
It is maybe that removing the transistor remove load and allow the amplifier to come up. It is possible channel A it is not the problem. All the voltage reading do not showed any abnormality that will allow us to determine for sure what it is the problem. We should start looking why the system shot down the power immediately.
Maybe we may need to recap. I was reading the instructions and found that
3 thing can caused the problem.
1- I PROTECTION - power will turn off instantly. Abnormal amplifier current flow - Display will work
2-PS PRT - display power turn off after .5 second -Display may not provide information - bad display PS
3-DC PRT - display bad channel DC output
One of the member recommend to check the fault signals
mcu pin 36 = PRD DC protection should be 0 = good 1 = fault detected
mcu pin 35 = PRV V protection should be 0 = good 1 =fault detected
mcu pin 44 = PRI I protection should be 0 = good 1 = fault detected
My suggestion it is install all the transistors back and test the voltage at the mcu pins to see which it is the one it is killing the power supply.
Does the display worked?
It is maybe that removing the transistor remove load and allow the amplifier to come up. It is possible channel A it is not the problem. All the voltage reading do not showed any abnormality that will allow us to determine for sure what it is the problem. We should start looking why the system shot down the power immediately.
Maybe we may need to recap. I was reading the instructions and found that
3 thing can caused the problem.
1- I PROTECTION - power will turn off instantly. Abnormal amplifier current flow - Display will work
2-PS PRT - display power turn off after .5 second -Display may not provide information - bad display PS
3-DC PRT - display bad channel DC output
One of the member recommend to check the fault signals
mcu pin 36 = PRD DC protection should be 0 = good 1 = fault detected
mcu pin 35 = PRV V protection should be 0 = good 1 =fault detected
mcu pin 44 = PRI I protection should be 0 = good 1 = fault detected
My suggestion it is install all the transistors back and test the voltage at the mcu pins to see which it is the one it is killing the power supply.
I dont have DBT. I will need to build one.
This amp does not even power on with Q168 in, and that is the same case with the one from Q175 or its original one. The Q168 location has something in that circuit that overloads the circuit. It doesn't even make it to the .5 second mark. Display doesn't light, nothing comes on.
Removing Q168 and it powers up and display works and it makes sound on 1 channel.
Cool.
Srinath.
This amp does not even power on with Q168 in, and that is the same case with the one from Q175 or its original one. The Q168 location has something in that circuit that overloads the circuit. It doesn't even make it to the .5 second mark. Display doesn't light, nothing comes on.
Removing Q168 and it powers up and display works and it makes sound on 1 channel.
Cool.
Srinath.
Hi,
Okay see if you can read these pins voltage to see which one it is causing the problem. You can do the check with the 168 out.
mcu pin 36 = PRD DC protection should be 0 = good 1 = fault detected
mcu pin 35 = PRV V protection should be 0 = good 1 = fault detected
mcu pin 44 = PRI I protection should be 0 = good 1 = fault detected
Okay see if you can read these pins voltage to see which one it is causing the problem. You can do the check with the 168 out.
mcu pin 36 = PRD DC protection should be 0 = good 1 = fault detected
mcu pin 35 = PRV V protection should be 0 = good 1 = fault detected
mcu pin 44 = PRI I protection should be 0 = good 1 = fault detected
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