TDA 2050 signal input security

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-----------i made the tda 2050 amplifier played for 30 min-in-low volume----suddenly volume became very

high crackling noise comes out along with song---so switched it off---then checked transformer and tda

2050 ic attached to a big heatsink--slighty warm---then checked power supply everything ok---

then again tried to play song----no sound --but speaker vibrating tremendously as it would burst out

making a booming sound----checked amplifier with another speaker same thing----


------MAIN ISSUE-------------

---i was using mobile phone and pc 3.5 mm jack output (inbuilt realtek soundcard in motherboard) as

signal source----after amplifier went wrong---

i used stereo headphones to check signal output of mobile and pc-----sound was coming out-------

---------BUT ONLY MUSIC AND HIGH FREQUENCY sound coming--VOICES IN THE SONG ARE ALMOST GONE JUST ECHOING

SLIGHTLY------------SO THE AMPLIFIER DAMAGED MY PC AND MOBILE PHONE 3.5 MM SOUND OUTPUT-------

---- :( :( :( :( :( :( :( :( :( :( :( :( :(---------------------MY QUERY IS----------- :( :( :( :( :( :( :( :( :( :( :( :( :( :( :( :( :( :( :( :(------

1----------IS THERE ANYTHING LIKE SIGNAL INPUT SECURITY IN TDA 2050 AMPLIFIER WHICH IN FUTURE WOULD KEEP

MY SIGNAL SOURCE DEVICES PROTECTED IN FUTURE ?

2----------MY BEST GUESS IS AMPLIFIER FAILED AND SEND POWER DIRECTLY TO SPEAKER AND SOURCE SIGNAL

DEVICES AS PC AND MOBILE so they are damaged------CAN ANYBODY TELL ME WHAT EXACTLY HAPPENED ?




------------------DETAILS OF TDA 2050 BUILD---------------




i made dual rail tda 2050 circuit---according to this----


DIY TDA2050 Hi-Fi Chip Amplifier (chipamp)

pcb diagram----http://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier/TDA2050-ChipAmp-PCB-

Component-Layout.pdf

parts list----http://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier/Updated-List-of-

Components-for-PCB.pdf

---------power supply--transformer dual rail---16-0-16 v ac------

22.5-0-22.5 v dc after bridge rectification 10 a and filter capacitor 2200 uf 50 v--------

power circuit looks similiar to this type-values are different--i have used--bridge rectification 10 a-

filter capacitor 2200 uf 50 v

https://cdn.instructables.com/FH7/T1DU/H8RVD01S/FH7T1DUH8RVD01S.MEDIUM.gif



-------------------thank you---------------------
 
Voices echoing means ... check the headphone or PC jack ground connection.


For protection You can use resistors in series. If You use say a 1K resistor, with 16V DC that would be 16mA, I think Your phone or PC would survive that.. but wait ... there is a 1 uF capacitor in the path....so DC shouldn't pass. Something must be very wrong on Your connections. I had the same problem on a china mixing desk where the inserted jacks touched the PCB and beneath the jacks was a 16V PCB track from the PSU.
 
-----------thank you


ok so for signal input protection for audio source device i use 1 k/1 watt in series in +ve signal wire---is it that you want to say----but i was thinking does that resistor reduce signal strength of audio source ?

-----what should be done in easy way for speaker driver protection ?
 
Take care the ic is correctly insulated from the heatsink otherwise heatsink contact with ground, perhaps sleeve of your headphone input plug or contact to your phone (iphone metal case) would cause a short. You'd probably notice if this had happened but if not the symptoms you described would be likely if the input ground track had burned through.
I've been caught out by this one with tda7295 where the connection of v- to the chips tab was not clearly specified to someone with limited experience.
hope you got it working
 
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