Breeze TPA3255 XLR Balanced Amplifier TearDown : DIP8 Op Amps.

[Doodski]

Welcome to ASR @ToniESP.

 

[ToniESP]

Yes, you have correctly generalized the easiest and most obvious modifications of this amplifier:
1. replace operational amplifiers with better ones (to your taste).
2. replace the 4 original Wima Caps 1µF or 2,2µF with 10µF to reduce phase distortion of the input signal.
Next are non-obvious modifications that can cause controversial opinions about their expediency:
3. if you have large speakers with 10 or 12-inch drivers, then you need to replace four 470µF/50V capacitors with two (three/four) LowESR 2200µF/63V electrolytic capacitors (this will be enough to provide dynamics at low frequencies). To test the dynamics at low frequencies, you can use these two audio-tracks. When listening through a good quality amplifier, the sound of a bass drum from first track resonates in your chest and makes it difficult to breathe.
4. replace the 30 kOhm resistor with 10 kOhm, which raised the frequency of the modulator from 450 kHz to 600 kHz. This will cause increased heating of the TPA3255 chip, so it is necessary to make ventilation holes in the upper cover of the case.
5. shunting a 220uF/63V electrolytic capacitor to power the chip TPA3255 with a 1nF/100V film capacitor to remove some of the high-frequency ripples.
6. we improve the quality of the power supply of operational amplifiers and the modulator in TPA3255 by replacing the parts around the converter voltage from 36-50V to 12V LM2575HV.

I made all six of these modifications on my amplifier and am pleased with their result!

1. View attachment 246438 or View attachment 246439
2. View attachment 246440 View attachment 246441 View attachment 246447
3. View attachment 246443 View attachment 246442
4. View attachment 246444 View attachment 246445
5. View attachment 246446
6. View attachment 246451 View attachment 246449 View attachment 246448 View attachment 246450

Hello,

Thank you for the detailed information regarding your amplifier modifications.

I was inspired by this idea and made modifications exactly according to your suggestions for choosing parts from Mouser and of course I changed the voltage to 42V.

Unfortunately, I have a problem - after turning on the amplifier, the inductor (Murata 19E225C) begins to heat up and smoke. This is not a disadvantage of this coil - I replaced it with a new one and the effect is the same, unfortunately ... What can cause this problem, should I use a different inductor? I compared the Murata 19E225C datasheet with the coils mentioned in the LM2575-12V datasheet and for example the Renco RL2448 is identical to the Murata 19E225C ...?

I enclose some photos and I will be grateful for any advice.

Greetings to all forum users.

 

[v1adpetrov2]

Unfortunately, I have a problem - after turning on the amplifier, the inductor (Murata 19E225C) begins to heat up and smoke. This is not a disadvantage of this coil - I replaced it with a new one and the effect is the same, unfortunately ... What can cause this problem, should I use a different inductor? I compared the Murata 19E225C datasheet with the coils mentioned in the LM2575-12V datasheet and for example the Renco RL2448 is identical to the Murata 19E225C ...?

Earlier in the discussion I wrote:
"First I set the inductance to 2200µH - there was a lot of RF interference.
Therefore, I installed another inductance, which I had in stock, at 1200µH - the level of interference was greatly reduced..."
And this inductor was wound with a wire designed for load current = 2A.

That is, when designing a reliable power supply circuit, using the rules of the old school, you need to take a current / voltage margin of 2 - 2.5 times more than the calculated figures.
And the inductance values can be from 470µH to 1200µH.

 

[ToniESP]

Earlier in the discussion I wrote:
"First I set the inductance to 2200µH - there was a lot of RF interference.
Therefore, I installed another inductance, which I had in stock, at 1200µH - the level of interference was greatly reduced..."
And this inductor was wound with a wire designed for load current = 2A.
View attachment 263837
That is, when designing a reliable power supply circuit, using the rules of the old school, you need to take a current / voltage margin of 2 - 2.5 times more than the calculated figures.
And the inductance values can be from 470µH to 1200µH.

Thank you for your explanations. This is my mistake - I did not read this thread carefully. I've already ordered new parts from Mouser and I'm getting to "work" ...

 

[NorTroll]

Hello! Been following this thread for a while, and decided to purchase one of these amps for myself!
Without modifications I must say I do enjoy the sound of the amp. But I do have a few questions, if referencing v1adpetrov2s list of 6 mods on the previous page. Does any of them make it so I have to do more mods? My initial thoughts are that I wanna do mod 1,2 and 3.

Secondly, I'm having an issue where after about 20 minutes of casual listening, I will lose sound on one channel. That channel proceeds to play a certain amount of white noise that isn't affected by the volume. If I turn it on and off again the problem sorts itself. Any common causes for this?

-NorTroll

 

[NorTroll]

Hello! Been following this thread for a while, and decided to purchase one of these amps for myself!
Without modifications I must say I do enjoy the sound of the amp. But I do have a few questions, if referencing v1adpetrov2s list of 6 mods on the previous page. Does any of them make it so I have to do more mods? My initial thoughts are that I wanna do mod 1,2 and 3.

Secondly, I'm having an issue where after about 20 minutes of casual listening, I will lose sound on one channel. That channel proceeds to play a certain amount of white noise that isn't affected by the volume. If I turn it on and off again the problem sorts itself. Any common causes for this?

-NorTroll

Sorted out the issue i was having, was caused by a bad RCA cable.

Any list where i can compare opamps anywhere?
-NorTroll

 

[ToniESP]

Thank you for your explanations. This is my mistake - I did not read this thread carefully. I've already ordered new parts from Mouser and I'm getting to "work" ...

Thanks again for this detailed information regarding your amp modifications.
I corrected my mistakes and made the modification exactly according to your recent suggestions on the selection of parts from Mouser and of course changed the voltage to 42V.
I have complete success! In fact, I should write that I am delighted with such a positive change in the overall dynamics and sound quality of this amplifier. I do not have the ability to make measurements, but I have two such amplifiers - so I directly compare the unmodified and modified one - playing the mono file on parallel amplifiers.

I also want to replace the 30kohm resistor with a 10kOhm one - is the one from Mauser 279-RP73D2A10KBTG suitable?

 

[v1adpetrov2]

I also want to replace the 30kohm resistor with a 10kOhm one - is the one from Mauser 279-RP73D2A10KBTG suitable?

Resistor 279-RP73D2A10KBTG is suitable for replacement.
But!!! This will cause increased heating of the TPA3255 chip, so it is necessary to make ventilation holes in the upper cover of the case.
Think twice - do you need it?

 

[sergedc]

Sorted out the issue i was having, was caused by a bad RCA cable.

Any list where i can compare opamps anywhere?
-NorTroll

Hi,
Did you open it yet? Is your board V1.5? Or has there been further changes?

FYI, this amp is now selling cheaper here : https://www.aliexpress.us/item/3256804855303917.html

 

[NorTroll]

Hi,
Did you open it yet? Is your board V1.5? Or has there been further changes?

FYI, this amp is now selling cheaper here : https://www.aliexpress.us/item/3256804855303917.html

My board is version 1.5 and the issue was actually not resolved it seems. Had a period of good luck where it did not trigger safety mode. Trying to figure out what causes it to trigger safety mode.

 

[v1adpetrov2]

My board is version 1.5 and the issue was actually not resolved it seems. Had a period of good luck where it did not trigger safety mode. Trying to figure out what causes it to trigger safety mode.

1. Disconnect the speaker from the amplifier and measure its resistance with a tester: if it is less than 3 Ohms, the TPA3255 chip will overheat and the protection will turn on.
Then the problem is in the technical condition of the speakers or crossover.
2. The manufacturer forgot to apply thermal paste to the radiator of the chip, in connection with which overheating occurs and protection is turned on.

 

[NorTroll]

1. Disconnect the speaker from the amplifier and measure its resistance with a tester: if it is less than 3 Ohms, the TPA3255 chip will overheat and the protection will turn on.
Then the problem is in the technical condition of the speakers or crossover.
2. The manufacturer forgot to apply thermal paste to the radiator of the chip, in connection with which overheating occurs and protection is turned on.

Hello, checked all the speakers I've tested with, they all measure at least 4ohms on my multimeter. And I have reapplied thermal paste to make sure it's a good amount. Is there anything other than overheating that can cause me to lose power on one channel? It happens even without volume. I'm thinking that maybe one of the relays are broken or something like that. Thank you for the reply.

 

[v1adpetrov2]

I'm thinking that maybe one of the relays are broken or something like that. Thank you for the reply.

Checking the relay is easy.
After the signal disappears in the loudspeaker, try to close the contacts of the input from the XLR and the signal output from the relay (red stripes in the photo).
If the sound appears in the speaker, then the relay is really faulty.

 

[NorTroll]

Checking the relay is easy.
After the signal disappears in the loudspeaker, try to close the contacts of the input from the XLR and the signal output from the relay (red stripes in the photo).
If the sound appears in the speaker, then the relay is really faulty.
View attachment 266799

since i do not have any xlr preamps, which ones are for the rca in and relay out? are there anything else that can cause the amp to behave the way it is? all speakers are measuring 7ohms, sound is there for 20-30 seconds before it makes a pop noise and sound on left channel goes away, chip never gets hot, power on output from power supply stays at 36v, i enjoy troubleshooting this but i soon have to send a refund request if i can not fix it.

 

[v1adpetrov2]

since i do not have any xlr preamps, which ones are for the rca in and relay out? are there anything else that can cause the amp to behave the way it is? all speakers are measuring 7ohms, sound is there for 20-30 seconds before it makes a pop noise and sound on left channel goes away, chip never gets hot, power on output from power supply stays at 36v, i enjoy troubleshooting this but i soon have to send a refund request if i can not fix it.

 

[Calleberg]

Hello! Been following this thread for a while, and decided to purchase one of these amps for myself!
Without modifications I must say I do enjoy the sound of the amp. But I do have a few questions, if referencing v1adpetrov2s list of 6 mods on the previous page. Does any of them make it so I have to do more mods? My initial thoughts are that I wanna do mod 1,2 and 3.

Secondly, I'm having an issue where after about 20 minutes of casual listening, I will lose sound on one channel. That channel proceeds to play a certain amount of white noise that isn't affected by the volume. If I turn it on and off again the problem sorts itself. Any common causes for this?

-NorTroll

My 2.1 BRZ TPA3255 amp (non XLR model) does a similar thing. But I can have music playing forever if I do not play very loud.

There are a few comments about similar issues in the Reviews from others that bought it and also at least one Youtube review with this issue.

It is the overcurrent protection that kicks in prematurely. Only Overcurrent and Overtemp needs a powercycle to Reset.
I hooked up a DMM to it and Current peaks of just over 2A triggers the protection like clockwork.

There is a resistor(resistors? don't rember exactly, did this over a year ago) that sets the current range/mode for the protection. But that checked out ok. In fact Everything checks out ok, Heat sink thermal paste is there. The amp chip solder connections look good, like everything else on the circuit board.

So, there is only two or maybe three possible failure modes here really.

#1 There IS an actual overcurrent situation, but in the HF domain, that means that a cap or coil in (most likely) the output filter is more or less shorting the Carrier to ground (saturating inductors maybe?). This would fit well with the behaviour of your amp, as the Carrier HF is on even without input signal, it also fits how my amp behaves, if in my case the component shorting the hf is just a little less faulty. ( being HF current a generic DMM, even a Fluke 179 like mine will not pick this up)

#2 Faulty/ Fake Amp Chip

#3 Same as #1 But related to Circuit board layout, improper layout causing parasitic capacitance which could also act as a short for HF, less likely as such a parasitic capacitance and HF current draw would have to be pretty substantial, I don´t think something of that magnitude would be possible and it also does not fit well with your failure mode as well as it does mine.

#4 A combination of the above

I have not done any modifications to my amp as I find it a waste of time. Nor have I made any serious effort to fix the actual issue I have. Instead I moved on and bought some Hypex UCD180 Modules.

I did eventually get a replacement board from BRZ that I have yet to try though.

Hope this helps...

 

[NorTroll]

okay, so update! my amplifier got fully refunded, and i blew the tpa chip when i accidentally shorted pin1 and 2 on the lm2575. currently looking at two options. 1 i order parts and fix the amplifier as it is, with potential upgrades, there are some bridged pads where the tpa3255 gets soldered to the board, but they are all connected either way, so i figgured that wont be an issue.

My option two, and this is the one i am most unsure about - It does sound like the option i will enjoy the most, and learn the most from.
I design a new pcb, Solder wires from the outputs of both opamps or anywhere from the outputs where its feasible to do so, assemble the new pcb with standoffs, bringing the new pcb high enough that i will have a protruding heatsink. Possible making room underneath for the bigger capacitors to fit. all while having a good time.

But i do have a few questions, why did they put 1k resistors between outputs on opamps and the 10uF caps for the inputs on the tpa3255?
is pin 4? on the relays supposed to go to ground?
And does any1 have suggestions as to what the best way of utilizing the fault and clip outputs on the tpa3255 is?
I desoldered quite a bit now, so if any1 wants a picture of the board pretty bare bones i'm more than willing to take a picture

 

[v1adpetrov2]

But i do have a few questions, why did they put 1k resistors between outputs on opamps and the 10uF caps for the inputs on the tpa3255?
is pin 4? on the relays supposed to go to ground?

1. Resistors of 1 kOhm are needed to protect the outputs of operational amplifiers, if the TPA3255 chip suddenly burns out and an increased voltage appears on pins 5, 6, 16 and 17.

2. Yes! Pin 4 on the relay must be earth-locked.