Hi All !
I'm here today because I bough a TDA8954BTL board, for some euros $$
I tested this week and sound seems good, but before all, I'm facning to a "sshhh" noise on each chanel.
I tested with a SMPS power supply (2x40.5V, without the two bridges on the board) and a classic tranformer with 2x24v AC. Noise is the same.
Have you an idea for solve the issue ? I will check the capacitors, because I'm affraid that these was fake..
Board : XH-M252 Ultra haute puissance BTL Mode Dual Stereo 24V 420W * 2 TDA8954TH F7L0 | eBay
(not this vendor)
I'm here today because I bough a TDA8954BTL board, for some euros $$
I tested this week and sound seems good, but before all, I'm facning to a "sshhh" noise on each chanel.
I tested with a SMPS power supply (2x40.5V, without the two bridges on the board) and a classic tranformer with 2x24v AC. Noise is the same.
Have you an idea for solve the issue ? I will check the capacitors, because I'm affraid that these was fake..
Board : XH-M252 Ultra haute puissance BTL Mode Dual Stereo 24V 420W * 2 TDA8954TH F7L0 | eBay
(not this vendor)
The first thing I would do is to remove the heatsink and check the snubber components. They should be 10R/2x220pF. Check if the resistor (10R) really measures 10R or it is open. If open, the snubber capacitors are likely to be 220nF. Without the correct snubber component values you cannot rely on the performance of the TDA8954TH chip.
I checked the value of R, it's OK (9.9ohms)
For the capacitors, I will desoldered the parts tomorrow for check that.
The noise is more "Hmmmmmm" that "shhhh" !
For the capacitors, I will desoldered the parts tomorrow for check that.
The noise is more "Hmmmmmm" that "shhhh" !
If the snubber resistors are close to 10 Ohm you need not de-solder the capacitors for check, unless you are used to it.
"Hmmmmmmmmmm" and not "Shhhhhhhhhh" sounds like hum. If you short-circuit the inputs (no source) of the TDA8954TH board, do you then still have the "Hmmmmmmmmmmm"?
"Hmmmmmmmmmm" and not "Shhhhhhhhhh" sounds like hum. If you short-circuit the inputs (no source) of the TDA8954TH board, do you then still have the "Hmmmmmmmmmmm"?
I tried to measure with the capacitance meter when the capacitors are soldered but it doesn't work (= infinity), I tested this morning by desoldering and I have 0.275nF and 0.285nf.
It was not a problem for me, I have a hot air station at work 🙂
I will try this tonight for short cut the input.
For information, the caps on power line are 800µ, not 1000µ .... "Haaa les chinoiseries" 😀
It was not a problem for me, I have a hot air station at work 🙂
I will try this tonight for short cut the input.
For information, the caps on power line are 800µ, not 1000µ .... "Haaa les chinoiseries" 😀
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Disconnect the source and short-circuit the inputs to signal ground. That is the first test when analyzing hum.
Is your transformer connected directly to the amplifier board? The electrolytic decoupling capacitors on the board are absolutely insufficient in size and may be the reason for your hum (ripple on the supply rails).
Is your transformer connected directly to the amplifier board? The electrolytic decoupling capacitors on the board are absolutely insufficient in size and may be the reason for your hum (ripple on the supply rails).
Yes, I tested with the transformer directly connected to the board.
For the next tests, I will remove all fake caps, and connect 2ea 10000µ/100v caps, and add 2ea 100nf on the power lines.
For the next tests, I will remove all fake caps, and connect 2ea 10000µ/100v caps, and add 2ea 100nf on the power lines.
"Fake caps" are hardly the reason for hum. 2x10000uF external of the board and with an external rectifier bridge sounds like a much better idea.
Yep.
Other point, I checked the datasheet, and I checked some components on the board, mainly on the inputs configuration. I see on the datasheet that the inputs must be connected in anti parallel... And on the board, the inputs seems to be mounted strangly !
Left input are connected to In+ on TDA[1], and In- on TDA[2] -> OK
But In- on TDA[1] are connected to the ground via a capacitor. Some way for In+ on TDA[2].
And commun point is grounded on the inputs connector.
Is it a correct connection ?
Because I searched the schematic, but I only seen that :
https://www.electroyou.it/fidocad/cache/2884d7e71eb30e5de24b32f4f136c8e33e91aa88_3.png
And the inputs are not connected like my board..
Other point, I checked the datasheet, and I checked some components on the board, mainly on the inputs configuration. I see on the datasheet that the inputs must be connected in anti parallel... And on the board, the inputs seems to be mounted strangly !
Left input are connected to In+ on TDA[1], and In- on TDA[2] -> OK
But In- on TDA[1] are connected to the ground via a capacitor. Some way for In+ on TDA[2].
And commun point is grounded on the inputs connector.
Is it a correct connection ?
Because I searched the schematic, but I only seen that :
https://www.electroyou.it/fidocad/cache/2884d7e71eb30e5de24b32f4f136c8e33e91aa88_3.png
And the inputs are not connected like my board..
Sounds correct for non-balanced use of basically balanced IC inputs.
In this thread, posting #12, there is a schematic. Use that as guidance. NOT for component values!
In this thread, posting #12, there is a schematic. Use that as guidance. NOT for component values!
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pfff I just tart a test this tonigh, and one side is out 😱
I see that the 22R on the out are burned (but again 22R, I turn ON the power supply for only some seconds..)
I don't understand why -_- Nothing wrong, I used a 2x24v transfo, 2x10000uF, and simple bridge.
2x35V with that.
Now the board make a noise (tic tic tic) when I turn ON.
hm........
I see that the 22R on the out are burned (but again 22R, I turn ON the power supply for only some seconds..)
I don't understand why -_- Nothing wrong, I used a 2x24v transfo, 2x10000uF, and simple bridge.
2x35V with that.
Now the board make a noise (tic tic tic) when I turn ON.
hm........
Oh-no.
Would you happen to have a 2x12Vac - 2x18Vac transformer with a minimum of 20VA? If an amplifier board is not performing well, it is best to start with a lower supply voltage.
"Tic-tic" is (unfortunately) an indication of a failure that keeps on activating a protection functionality.
Try this: Disconnect the amplifier board from everything. Measure with an Ohm-meter the impedance from signal ground and to each of the four output lines. Any measurement below 100 Ohm? Then the same from supply "+" and to the four output lines. Finally from the "-" supply and to the four output lines. A measurement below 100 Ohm without power could mean a chip failure.
Would you happen to have a 2x12Vac - 2x18Vac transformer with a minimum of 20VA? If an amplifier board is not performing well, it is best to start with a lower supply voltage.
"Tic-tic" is (unfortunately) an indication of a failure that keeps on activating a protection functionality.
Try this: Disconnect the amplifier board from everything. Measure with an Ohm-meter the impedance from signal ground and to each of the four output lines. Any measurement below 100 Ohm? Then the same from supply "+" and to the four output lines. Finally from the "-" supply and to the four output lines. A measurement below 100 Ohm without power could mean a chip failure.
I have 1kR between GNd and the inputs, and more than 20MR (infinite ?) between powers and outputs.
I connected my SMPS (2x41V), and no noise, no smoke.. Seems ok !
So ! I don't understand, the problem seems come from my power supply ! It's just a classic transfo+bridge + caps !
I connected my SMPS (2x41V), and no noise, no smoke.. Seems ok !
So ! I don't understand, the problem seems come from my power supply ! It's just a classic transfo+bridge + caps !
The stupid question, you turned the capacitors right and they have a voltage rating of at least 50V? Please test the power supply without the amplifier board connected.
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Yes because it's very big caps (12cm * 6cm, 100V), and if I turn wrong these caps, I'm dead ^^ I tested without load, and I have 35.5V on each rail.
So, I tested the two channel with the SMPS with sound, they seems ok. And, the "hum" noise has disappear ! Maybe the fake caps so...
But for the power supply, I don't know. Maybe my bridge is dead, or the caps.. I will check tomorrow.
So, I tested the two channel with the SMPS with sound, they seems ok. And, the "hum" noise has disappear ! Maybe the fake caps so...
But for the power supply, I don't know. Maybe my bridge is dead, or the caps.. I will check tomorrow.
that IC has a quite high SNR tolerance, I used that with an additional feedback loop for multiple car-audio customers(kicker, jl, rockford, audison and a bunch of smaller). The trick reduces noise for 10-15db and THD by factor 5 at -3db power. I did post the schematic of that a few years ago on that forum.