I recently purchased the sure electronics TDA7498 6x100watt amplifier. I also purchased 8ohm 100watt speakers to run the unit on. I was using my amplifier without any issues and unmodified. I have a 36v 350 wats switching power supply and it is running correctly. All of a sudden one of the tda chips burned out on the output of the unit. I can seem to figure out why this would occur. I was playing music from my iPhone with a phono to RCA cable, the DIP switches set for weak amplification as high was not needed. What would cause the output to melt and blow a hole in the chip? I am receiving a new board on warranty because I did not go beyond the directions and took ever precaution. I want to make sure that it does not happen again.
If anyone has suggestions or questions for more details, please provide input.
Thank you,
Neohd
If anyone has suggestions or questions for more details, please provide input.
Thank you,
Neohd
I think the reason this occurred was the input received a high frequency from my iPhone or when a phone call came in at the same time I was playing music. I realized that the iPhone has a RMS output of about 1v with a 60K impedance. This is acceptable from the Amplifiers perspective but could be a little lower. Now this is the only thing that I can think of, so I plan on building a small low-pass filter to filter out frequencies above 25kHz since this is well outside the audible range. I read that high frequencies above 60kHz cause a large amount of current to build up in the output filter on these boards, which I am not sure if this happened, but is so far the only explainable reason I can figure out.
That does make a certain amount of sense. Speaker / headphone drivers in phones have been class-D for quite some time now, and you can bet your a*s they use as little filtering as they can/need just to pass EMC testing...
One last thing that concerned me but might not be related to the issue I had was in the manual of the device it states the following warning:
"You are allowed to feed only one group (dual channel) of audio signal to the amplifier board at a time."
Now, I purchased this device to run several speakers not just two. What is the risk and why is this in the manual? Has anybody had problems with running the device with all 6 outputs running?
"You are allowed to feed only one group (dual channel) of audio signal to the amplifier board at a time."
Now, I purchased this device to run several speakers not just two. What is the risk and why is this in the manual? Has anybody had problems with running the device with all 6 outputs running?
New Enlightenment on this front. I had noticed some issues with the replacement Amplifier low audio vs previous device plus it started to go down the same road as the previous amp. So I decided to remove the heat sink to take a look at the chips, after cleaning them and verifying everything was good, I noticed that the board did not contain the 100W chips, but rather the TDA7498L(80W) model. I will be replacing them with the 100W versions and running the system to verify everything is looking good.
Thought I would share this concerning piece of information.
Thought I would share this concerning piece of information.
If this is true, then Sure is cheating on the customers. Are these boards bought from genue Sure or an official Sure dealer?
I would think of a thermal problem (bad heatsink connection) or shorts under the heatsink.
To me, this only means that you are allowed to connect just one source. That doesn't mean that you can only connect two speakers at the same time.
I would think of a thermal problem (bad heatsink connection) or shorts under the heatsink.
To me, this only means that you are allowed to connect just one source. That doesn't mean that you can only connect two speakers at the same time.
Sure electronics using different chips than claimed was reported before:
Trevor Marshall - Class D Audio Amplifier Design - TDA7498 Output filters
There it were higher graded chips.
I had one TDA7498 blown without visible reason, too.
It was on a board like this, bought from a random aliexpress-seller.
It was obviously the chip that failed as there was a visible burnt spot on it.
Trevor Marshall - Class D Audio Amplifier Design - TDA7498 Output filters
There it were higher graded chips.
I had one TDA7498 blown without visible reason, too.
It was on a board like this, bought from a random aliexpress-seller.
An externally hosted image should be here but it was not working when we last tested it.
It was obviously the chip that failed as there was a visible burnt spot on it.
The board is labeled 'yuanjing'.
Has nothing to do with sure.
But is a 7498 and it failed, too.
Whats the matter getting better stuff than advertised? *98 is "better" than *92, so what?
To me the reason for all those faults is easy, most of these layouts are just crap - so is thermal performance. (Beside the fake/bstock/recycled passive components) You just get what you pay for.
They are cheating a little maybe, but the 7498L could very well be 100w @ 36V, the "L" 80W spec is @ 32V.
Are you connecting all amplifiers to speakers ?
Class d is a bit fussy about having no load.
The output inductor rings and generate high voltages and blow the output filter capacitor. This will short out the amplifier module.
I always fit high voltage capacitors on my class d amps to stop that occurring.
Class d is a bit fussy about having no load.
The output inductor rings and generate high voltages and blow the output filter capacitor. This will short out the amplifier module.
I always fit high voltage capacitors on my class d amps to stop that occurring.
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