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Old 10th July 2014, 02:57 PM   #1
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Default lm1876 problems

hi guys .

first of all please excuse my english. secondly i builded un amplifier using the schematics for typical aplicatLM1876-circuits.jpgion my problem is that i have 18 v in both outputs. when i try to atach the speakers the source transformer 63 v 200w starts to make un huge noise and also the speakers . if i conect the speaker trough un polarized capacitor in series then the amplifier starts working and after that if you remove the capacitor works also . after power down same story again. can any of you please help me
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Old 10th July 2014, 03:17 PM   #2
Mihkus is offline Mihkus  Estonia
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63 what? Volts V?
64V DC is its maximum supply voltage.... 63AC to DC is nearly 90V without load...
You chip is probably blown because you need split supply... and resistor between input and GND ...
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Old 10th July 2014, 03:30 PM   #3
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i build this amplifier as un replacement for front chanells amplifier in genius sw hf 5,1 5005 the suply the transformer has 63 v indeed but i used his internal split power suply with +18 -18 v the amplifier still work but my problem are at start when it doesnt stars and the transformer vibrate unless i put un capacitor in series with the speakers . i might uses it with that capacitor but is not ok it at high frequencies and mids sounds ok but the buss its almost inexistent . when i remove the capacitor and i connect the witout it the amplifier sounds at least ok both hi and lows also the transformer noise but again after power down i nedd to conect again the capacitor and after that to remove it and connevt the speakers
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Old 10th July 2014, 03:31 PM   #4
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i forgott what do you mean with resistor between input and ground
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Old 11th July 2014, 10:04 PM   #5
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aparently by adding the zobel network from auxiliary schematics of the texas instruments lm1876 datasheet putting 0.1uf capacitors in parallel with the bypasing caps and putting the stand by pins to ground solved my problem . the amplifier works now without problems(when now sound are played through him you can hear un sound like zzzzzz if you put you ear close to speakers). besides that sounds great and its a great improvement versus original tda7269 amplifier. thank you all who gived un thought to try to solve my problem

Last edited by redcristi; 11th July 2014 at 10:21 PM.
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