TDA 2050 SIGNAL INPUT SECURITY

[rahulrahullll]

------------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----


https://diyaudioprojects.com/Chip/DIY-TDA2050-Hi-Fi-Chip-Amplifier/

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

**broken link removed**



-------------------thank you---------------------

 

[Rich D.]

Without inspection I can't say what was wrong, but there must have been a fault with C1, 1uF or its wiring to cause damage to what was driving the amplifier.
For such a small value, C1 could easily be found at 50 or 100 volts. I would avoid using an electrolytic there, they are more failure prone - perhaps a Mylar or poly cap of some sort.

C1 is supposed to protect the input source and/or the TDA from any strong or steady DC voltage.
Whether or not the TDA has a fault the C1 capacitor should have prevented the damage to the source's output. Still, something else must have failed also to create this voltage.
The music sources (PC, phone...) outputs have been designed to withstand a shorted output, so the problem is more than just a shorted output.
You had a significant voltage on the input that was enough current to destroy the outputs. That voltage shouldn't have been there, and the capacitor should not have allowed that current to flow.

 

[rahulrahullll]

thank you----right now---amplifier working again everything ok-a resistor was loose i resoldered it-setup everything

i have taken a cable with one end 3.5 mm single jack-inserted to pc-set to 2 channel mode---other side 2 jacks of which one only i have put in input of amplifier other kept hanging---------IS THIS OK ?

----but right now amplifier sounding ok but my mobile phone and pc sound out ---mid part voice missing in songs when used stereo mobile headphones--but if i lightly insert the jack then sounds ok all frequencies----WEIRD----but when i connect to amplifier by 3.5 mm jack (this jack is bigger in size than the mobile headset) cable all sound frequency ok-----------WEIRDDDDDDDDD--------


-----------------ANY IDEA WHAT IS HAPPENING--------


what do you think---if amplifier chip fails or malfunction sometime---then is it possible that high voltage will enter source signal devices ?

---is there any possibility like that ?

 

[Rich D.]

First question: I'm not really sure how you have it connected, but if you are saying you are taking a stereo signal and only putting one side (left or right) in the amplifier ... that is OK.

Sounds like the ground wire is going in-and-out on the headphones. That does some weird stuff with the sound sometimes. Erratic connections with those audio wires can do all sorts of things at random times. Make sure every contact and wire is CLEAN and well connected. Give it a good wipe...sometimes invisible oil or oxidation can't be seen but is enough to cause resistance and audio issues. Look for tiny little shorts with a single strand of a stranded wire at connector ends where a mechanical strain relief should be - that happens some times. Wire-to-connector failures are #1 most common problem.

The fact that sometimes the PC or phone can sound OK is proof that they aren't permanently damaged. Lucky you.

Last question: All failures are possible, but not very likely. Modern devices have outputs that are usually protected against electro-static-discharge (shocking from a finger, etc.) and lower voltage failures. They have transient-voltage-suppressors (TVS), a current limiting resistor and sometimes steering diodes for DC voltages, as well as a capacitor also. Products sold in the EU are required to have some protection so most manufactures make that same design for the entire world. But seriously high voltages can blow thru anything! (take lightning for example, Nothing's impossible. More likely an insect will walk across a high voltage and create a temporary short and bug zapper.)

IF you have a well-built circuit with good components and quality solder joints, an amplifier failure is not likely to destroy the output of the music source.
It is more likely that a very powerful music source will destroy the input of an amplifier. The TDA chip can be destroyed by a +/- 15 volt signal on the chip pin's input. The output of the TDA is thermally and short-circuit protected though.
The schematic shown in the chip spec is a minimum, get-it-working design. I would add input protection that includes a small ferrite bead and a few tens of puffs of capacitance, and some TVS diodes. That's what you would find in a commercial product.

If you are driving an expensive speaker system, I would have an output fuse (at least on the tweeter). The input fuse on the power supply is absolutely necessary if you want to remain alive. Also, many designs will have fuses on the power supply DC outputs, or at least a reset-able poly fuse or a current limiter. These are features commercial manufacturers usually include. It may cost a bit more, but saves them a lot of bad reputation with product failures. It's one of those pay-me-now or pay-me-later deals.

 

[rahulrahullll]

i made pcb---i connected like this--------amplifier input capacitor is this one only value is 1 uf/250v

https://diyaudiocart.com/Electronics-Parts/Capacitors/DEC-2.2-MFD-250V-Axial?sort=p.price&order=ASC



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

https://diyaudioprojects.com/Chip/D...fier/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---2 nos 1 for each rail-----

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

filter capacitor 2200 uf 50 v

**broken link removed**

 

[audioguru]

We explained why the headphones sound weird, they have a missing ground connection which causes the headphones to play only the difference between left channel and right channel.
Mono and most low frequencies is the same signal in both channels and if the ground wire on headphones is not connected to the amplifier ground then they play the difference between the channels that is nothing. Stereo has a difference between channels for high frequencies and echoes which are heard loudly when the headphones have the ground wire not connected to the amplifier.