Hello,
i bought this amp a few years ago with a broken PS and Audio. Fixed this a few years ago, tested, but had a power off bump in the sub. I decided a few weeks later, too work again on it, but it stays in protect from the beginning.
Now, 2 years later, i had time to work on it again. Connected it to a sub, and a multimeter.
Powered up, dc offset up to 4VDC, slowly decreasing to 0.6VDC. Amp works fine in this state, without protection . But with this little offset, you can hear a little bump.
Anyway, i think it wont work reliable.
Removed the Pre amp board, no dc offset. LED isnt lit, but draws the normal current 0f 1.4Amps.
Any suggestions?
i bought this amp a few years ago with a broken PS and Audio. Fixed this a few years ago, tested, but had a power off bump in the sub. I decided a few weeks later, too work again on it, but it stays in protect from the beginning.
Now, 2 years later, i had time to work on it again. Connected it to a sub, and a multimeter.
Powered up, dc offset up to 4VDC, slowly decreasing to 0.6VDC. Amp works fine in this state, without protection . But with this little offset, you can hear a little bump.
Anyway, i think it wont work reliable.
Removed the Pre amp board, no dc offset. LED isnt lit, but draws the normal current 0f 1.4Amps.
Any suggestions?
No, there is no Pot for DC. I cant test up to clipping right now, because my dummy loads are not here. I could test it in two weeks.
The DCO seems to change quite a bit and was never 0.6v.
Does changing the position of any of the switches or pots make a difference in DCO? Let the amp have a minute or so to settle if the DCO is drifting after the change.
That's a lot of hum (from lighting or other electrical noise from the mains?). Does that go away if you install shorting plugs in the RCA input jacks?
Does changing the position of any of the switches or pots make a difference in DCO? Let the amp have a minute or so to settle if the DCO is drifting after the change.
That's a lot of hum (from lighting or other electrical noise from the mains?). Does that go away if you install shorting plugs in the RCA input jacks?
The 'hum' was from looking at a waveform with a 10ms timebase.
The waveforms with the 5us timebase are residual from the carrier and insignificant.
This is 0.1v of offset. That's far from 0.6v. Did that cause a turn on/off pop when driving a subwoofer?
The offset is 0.004v without the preamp board. Does the preamp board have an op-amp with significant DC offset?
The waveforms with the 5us timebase are residual from the carrier and insignificant.
This is 0.1v of offset. That's far from 0.6v. Did that cause a turn on/off pop when driving a subwoofer?
The offset is 0.004v without the preamp board. Does the preamp board have an op-amp with significant DC offset?
I checked the +-15 V and +-5 V with preamp Board inside,to See,If there is any difference during Start Up. Everything Looks fine. Now the amp stays in protect during Power Up. After a third try to Power Up,i got a little bang. Have to Look now First,what Happens..
The DCO was only in the First Minute. It slowly decreases from 4v to 0.1v. I expect a dead capacitor for this Problem, because everytime i started Up,it becomes a little better..
But now,i have to Look what Happens.
The DCO was only in the First Minute. It slowly decreases from 4v to 0.1v. I expect a dead capacitor for this Problem, because everytime i started Up,it becomes a little better..
But now,i have to Look what Happens.
I will try to remove the Op amps from the pre amp board one by one, and check wether the problem is gone or not. I dont have cables at the moment,
to work in the board outside the mainbord.
to work in the board outside the mainbord.
Wouldn't it be much easier to make up cables?
You can't just remove them. You would have to replace them because the removal of one would break the connection to all before it.
How loud is the pop? 0.1v isn't going to make much of a pop. Does it possibly have a turn on/off transient that's not related to the steady DC offset?
You can't just remove them. You would have to replace them because the removal of one would break the connection to all before it.
How loud is the pop? 0.1v isn't going to make much of a pop. Does it possibly have a turn on/off transient that's not related to the steady DC offset?
I think, the DCO and the Pop are different problems, maybe the DCO isnt a problem, because in less than a minute, the DCO is gone.
The Pop depends, on how long the amp runs, and how much gain i have given. The Pop is only at switch off.
The DCO is at power up only. DCO raises within 5 seconds, to about 4V,not audible.
Maybe there is an op amp damaged, or circuit for this. I dont know, how the amp works, but it seems to me, that the microcontroller is detecting the DCO, and start reducing the DCO. When the amp switched off, the microcontroller switches off, and the DCO is back for that moment of switching and cause the pop.
The Pop depends, on how long the amp runs, and how much gain i have given. The Pop is only at switch off.
The DCO is at power up only. DCO raises within 5 seconds, to about 4V,not audible.
Maybe there is an op amp damaged, or circuit for this. I dont know, how the amp works, but it seems to me, that the microcontroller is detecting the DCO, and start reducing the DCO. When the amp switched off, the microcontroller switches off, and the DCO is back for that moment of switching and cause the pop.
The DC is rarely controlled by a MCU. It's almost always done op-amps.
You need to determine if the muting is switching on/off properly. I'm not sure what they use for muting. Does the SD voltage for the output ICs correspond to muting?
You need to determine if the muting is switching on/off properly. I'm not sure what they use for muting. Does the SD voltage for the output ICs correspond to muting?
Mute ist working well. Here are two ir2010s installed. Pin 13 is sd. I have 5V,until Rail ist build.if i remove remote,a second later 5V is applied again,until the amp Switch Off completly.
But,you can See and hear,that the Pop is audible,a microsecond,before the mute switches on.
But,you can See and hear,that the Pop is audible,a microsecond,before the mute switches on.
I load Up two Videos on YouTube for you. You can See the Offset in the First Video,and mute with Offset on the second video