Hi All
I have a slightly different use for an amplifier board. I am trying to drive 100 Volt line speakers for a Public Address system, using 2 step up transformers connected to the output of the amp.
Power supply is a 150 Watt (Mean Well LRS-150-36) - set to 32 Volts.
I have been using a TDA7498 board that I bought of ebay:
TDA7498E Digital Power Amplifier Board Single Channel 2x160W Audio Stereo Module | eBay
I can set it all up, and it works fine, and am able to draw 50 Watts per channel (my target Wattage), so I am happy with this.
I have been running in to issues though with the board when I power it down. Sometimes, when I power the board down, I hear a a faint crack, and when it is powered back up again I get plenty of smoke! Removing the heat sink, I can see that the power input pins to the IC is fried (pins 6&7, and pins 12&13). So far this has happened on 4 boards, so it is getting expensive!
I am not sure, but I think this has happened without speakers connected every time, and without audio being fed to the amp.
What could be happening, and more importantly, what could I do to stop this occurring? The only thing I can think of, is that it doesn't like the 100 Volt toroids on the output, which may present too low a load. When the amp is powered down, could there be a DC current put across the toroids which in turn puts a back EMF through the amp? I don't know enough about these things, so am hoping to make use of all your greater experience!
I have used a TPA3116 board previously, and this works fine. I now need to step up the power now, hence why I am trying the TDA7498 board
Thanks for any advice that you may be able to give!
Mike
I have a slightly different use for an amplifier board. I am trying to drive 100 Volt line speakers for a Public Address system, using 2 step up transformers connected to the output of the amp.
Power supply is a 150 Watt (Mean Well LRS-150-36) - set to 32 Volts.
I have been using a TDA7498 board that I bought of ebay:
TDA7498E Digital Power Amplifier Board Single Channel 2x160W Audio Stereo Module | eBay
I can set it all up, and it works fine, and am able to draw 50 Watts per channel (my target Wattage), so I am happy with this.
I have been running in to issues though with the board when I power it down. Sometimes, when I power the board down, I hear a a faint crack, and when it is powered back up again I get plenty of smoke! Removing the heat sink, I can see that the power input pins to the IC is fried (pins 6&7, and pins 12&13). So far this has happened on 4 boards, so it is getting expensive!
I am not sure, but I think this has happened without speakers connected every time, and without audio being fed to the amp.
What could be happening, and more importantly, what could I do to stop this occurring? The only thing I can think of, is that it doesn't like the 100 Volt toroids on the output, which may present too low a load. When the amp is powered down, could there be a DC current put across the toroids which in turn puts a back EMF through the amp? I don't know enough about these things, so am hoping to make use of all your greater experience!
I have used a TPA3116 board previously, and this works fine. I now need to step up the power now, hence why I am trying the TDA7498 board
Thanks for any advice that you may be able to give!
Mike
If the amp was muted instantly at power off, only a 50% duty cycle is offered by the driver stage whilst the power subsides, helping to avoid errors and both output transistors being turned on at the same time.
They don't like slow decay of power. What are you using as a power supply? Ideally a smpsu with minimal smoothing is best. To add extra smoothing is not recommended.
As an aside, how do you get enough power through a 2.1mm 3Amp maximum DC jack for full power? Hmm.
They don't like slow decay of power. What are you using as a power supply? Ideally a smpsu with minimal smoothing is best. To add extra smoothing is not recommended.
As an aside, how do you get enough power through a 2.1mm 3Amp maximum DC jack for full power? Hmm.
Hi JonSnell, thanks for taking the time to reply!
Power Supply is a Mean Well 150 Watt 32 volt -
http://www.meanwell.com/productPdf.aspx?i=420
There is no additional smoothing.
So if I mute the amp before powering down, you think it may stop frying the TDA7489? I am not sure how I can handle this if the board is accidently powered down though!
Good point about the power connector - thats one of the reasons I chose this board as it has screw terminals, rather than a plug in connector!
Once again, thanks for your time
Mike
Sent from my SM-G930F using Tapatalk
Power Supply is a Mean Well 150 Watt 32 volt -
http://www.meanwell.com/productPdf.aspx?i=420
There is no additional smoothing.
So if I mute the amp before powering down, you think it may stop frying the TDA7489? I am not sure how I can handle this if the board is accidently powered down though!
Good point about the power connector - thats one of the reasons I chose this board as it has screw terminals, rather than a plug in connector!
Once again, thanks for your time
Mike
Sent from my SM-G930F using Tapatalk
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