hi
i am impatient...i did it!
i set the chip on 20V rail and it worked fine. so now its a TDA2040.
correct?
i let the amp run on its clipping border = 500mVrms with my sweep 5 minutes at 8R and its survived. the chip has 59°C then i stopped and cooled with fan.
pic 1 is the consumption during 500mVrms 1khz on 8R
pic 2 is the scope probe ...its about 11,1V rms = 15,5 Watt
chris
good night
i am impatient...i did it!
i set the chip on 20V rail and it worked fine. so now its a TDA2040.
correct?
i let the amp run on its clipping border = 500mVrms with my sweep 5 minutes at 8R and its survived. the chip has 59°C then i stopped and cooled with fan.
pic 1 is the consumption during 500mVrms 1khz on 8R
pic 2 is the scope probe ...its about 11,1V rms = 15,5 Watt
chris
good night
Attachments
Without magic smoke there is no glory
I have used mine with +/- 20V and without problems
Hi Jose
yes...i have a lot of kits with fake lm1875...so if something happened...TDA have to pay for
Without magic smoke there is no glory
I have used mine with +/- 20V and without problems
I supplied mine with +/- 26V and of course it went off in smoke.
Lesson learned: China PCBs ok. Components in the bin.
Or what do you all think?
Are any China Components ok?
Resistors perhaps?
good morning kurtvisti
yes the pcb is ok. the components are maybe not the best but using +/-26V per rail is not recommended to any of these chips. TDA2030,2040, 2050 not more then 25V- datasheet .....the lm1875 is ok with +/- 30V at 8R and not at 4R!
actually my TDA2040?- fake 1875 is running since 90minutes with 20V per rail with a sweep of 10hz-35khz with 100mVrms. and the temp is on the chip 48°C. this is fine....don´t forget that no genuine TDA2030,2040,2050 is active or will be produces - so we have to expect a fake.
as i wrote i am surprised with the amazon kit that this chip can handle 25V per rail and give the recommended 20WAtt at 8R
so its definitive no TDA2030 - know i believe its a better one. its important to check because my transformer is a 18 -0 -18V AC = 25V DC.
chris
yes the pcb is ok. the components are maybe not the best but using +/-26V per rail is not recommended to any of these chips. TDA2030,2040, 2050 not more then 25V- datasheet .....the lm1875 is ok with +/- 30V at 8R and not at 4R!
actually my TDA2040?- fake 1875 is running since 90minutes with 20V per rail with a sweep of 10hz-35khz with 100mVrms. and the temp is on the chip 48°C. this is fine....don´t forget that no genuine TDA2030,2040,2050 is active or will be produces - so we have to expect a fake.
as i wrote i am surprised with the amazon kit that this chip can handle 25V per rail and give the recommended 20WAtt at 8R
so its definitive no TDA2030 - know i believe its a better one. its important to check because my transformer is a 18 -0 -18V AC = 25V DC.
chris
25V rail ... no smoke
Hi
i did it !....25V per rail and no smoke
pic 1 idle
pic 2 +3 1khz with 100mVrms at 8R
pic 4+5 1khz with 600mVrms at 8R near clipping
13,1 Vrms on the scope give me 21,4Watt at 8R calculated...
so my chip is fine
chris
Hi
i did it !....25V per rail and no smoke
pic 1 idle
pic 2 +3 1khz with 100mVrms at 8R
pic 4+5 1khz with 600mVrms at 8R near clipping
13,1 Vrms on the scope give me 21,4Watt at 8R calculated...
so my chip is fine
chris
Attachments
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kit 1 aliexpress_25Vrail_idle.jpg239.5 KB · Views: 252
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kit 1 aliexpress_25Vrail_100mVrms input 8R_1.jpg171 KB · Views: 261
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kit 1 aliexpress_25Vrail_100mVrms input 8R_2.jpg246.5 KB · Views: 252
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kit 1 aliexpress_25Vrail_600mVrms input before clipping 8R_1.jpg251.1 KB · Views: 59
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kit 1 aliexpress_25Vrail_600mVrms input before clipping 8R_2.jpg182.3 KB · Views: 56
i did it !....25V per rail and no smoke
And you have let the power on for a longer period of time?
Good morning.
+/- 26V is out of specifications, so magic smoke is a logical consequence.
I know that TDA have been off the production line for years but I don´t know another chip that has similar characteristics to LM1875. In all the websites I have consulted they talk about TDA models.
The good news for all (thanks to Chris's tests) is that the fake chip is good enough. How much? I do not know
+/- 26V is out of specifications, so magic smoke is a logical consequence.
I know that TDA have been off the production line for years but I don´t know another chip that has similar characteristics to LM1875. In all the websites I have consulted they talk about TDA models.
The good news for all (thanks to Chris's tests) is that the fake chip is good enough. How much? I do not know
Good morning.
+/- 26V is out of specifications, so magic smoke is a logical consequence.
Morning,
My ebay kit chips says LM1875 so therefore not out of specifications.
I don’t want a TDA20xx or a TDA20xx lookalike in my LM1875 amp.
Decent quality components bought instead....for me life is to short for fakes and poor quality.
Sure, you are right. What I mean is that to be a fake (a TDAXXXX), the chip does its job in an acceptable way.
As I said before, the cost of the kit is about 2€ or 3€ for me the PCB is the important thing, the rest of the components is simply a gift.
However, although I have original LM1875, I am curious to know what chip they have used for counterfeiting.
Jose
As I said before, the cost of the kit is about 2€ or 3€ for me the PCB is the important thing, the rest of the components is simply a gift.
However, although I have original LM1875, I am curious to know what chip they have used for counterfeiting.
Jose
As for the audio quality, I can tell you that so far, the differences I have found have been greater "brightness" in the LM1875. The fake has a "warmer" profile.
If you mean pure measurements, both were quite linear in a sweep of 20Hz to 20Khz although I only used a voltage of +/- 15vDC and +/- 18vDC for these tests, so take this with tweezers.
Chermann has a better laboratory tools so maybe he can provide more data.
If you mean pure measurements, both were quite linear in a sweep of 20Hz to 20Khz although I only used a voltage of +/- 15vDC and +/- 18vDC for these tests, so take this with tweezers.
Chermann has a better laboratory tools so maybe he can provide more data.
Hi again
so 4 hours test of the fake...i will say tda2050is done. 70mVrms input with my sweep let the chip run at 40°C with this heat sink configuration.
additionally to this i let this chip run at 5 minutes full power= 600mVrms sweep , 25V rail and 8R load. its about 13,5Vrms = 22,7Watt calculated.
the chip gets after 2 min about 73 °C then its stable up to 5 min...then i cooled it with fan.
i do all this effort like my class D chip projects. my amps had to run very long before i go to my good speakers. now i tested just the amp board and i have to check the other chips i have got....
yes you are right - the power says nothing about the sound. my first step must be to check the rail voltage i can handle because of my trani. so this is done.
i am not able to measure THD so i will try with rectangle or square to find some "ringing/oscillation"...i am not an expert guys
and yes this kit give me a lot of fun and much learning headache
BTW....my son is 11years and he finished a kit well...
chris
so 4 hours test of the fake...i will say tda2050is done. 70mVrms input with my sweep let the chip run at 40°C with this heat sink configuration.
additionally to this i let this chip run at 5 minutes full power= 600mVrms sweep , 25V rail and 8R load. its about 13,5Vrms = 22,7Watt calculated.
the chip gets after 2 min about 73 °C then its stable up to 5 min...then i cooled it with fan.
i do all this effort like my class D chip projects. my amps had to run very long before i go to my good speakers. now i tested just the amp board and i have to check the other chips i have got....
yes you are right - the power says nothing about the sound. my first step must be to check the rail voltage i can handle because of my trani. so this is done.
i am not able to measure THD so i will try with rectangle or square to find some "ringing/oscillation"...i am not an expert guys
and yes this kit give me a lot of fun and much learning headache
BTW....my son is 11years and he finished a kit well...
chris
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...and yes this kit give me a lot of fun and much learning headache
BTW....my son is 11years and he finished a kit well...
This is one of the best parts of this hobby.
Hi rabbitz
thanks for your hint but i go for 18-0-18 and these transformers are on my bench,
i did a 6 hours test with my aliexpress kit with 100mVrms sweep , 25Vrail 8R load ....its about 2,3Vrms output....0,7Watt......the chip gets stable with 46°C all the time....so for me this fake is a TDA2050.
now i test the second ali kit (from my son) and it worked with 25V per rail too.
test is ongoing.....running at 46°C stable...
DC offset is 0,1mV !!!
chris
thanks for your hint but i go for 18-0-18 and these transformers are on my bench,
i did a 6 hours test with my aliexpress kit with 100mVrms sweep , 25Vrail 8R load ....its about 2,3Vrms output....0,7Watt......the chip gets stable with 46°C all the time....so for me this fake is a TDA2050.
now i test the second ali kit (from my son) and it worked with 25V per rail too.
test is ongoing.....running at 46°C stable...
DC offset is 0,1mV !!!
chris
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