Hi I was wondering if anyone can Help with a TDA 2030 audio chip guitar amp oscillation problem that I'm having with my amp build.
I'm using a Single supply and using the Schematic from the Data sheet for single power supply application.
After finally getting the chip to amplify a guitar signal from a tl-072 pre amp, and figuring out where to put the volume control and what size pot to use,, I've managed to get the set up working.. Only problem is,, It oscillates at a particular volume setting.. I'm truly stumped here.. I'm using the components listed on the schematic, but i'm wondering if there is some other component that has not been included? How do I stop this tda 2030 from oscillating? Hope fully some one can help. Thank you...
Can you show us some pictures and the schematic you used?
Hi here is the schematic,, I hope,,,
I bet the schematic is fine, oscillation problems come from poor layout or shielding, poor grounding, etc.
Have you installed C3/ C9 (0.1 uf) & R4/ R10 (1 ohm)?
Hi J.P.. Hi J.M.. Thank you for your replies,, Yes I have installed C3 (.1uf) and R4 (4.7ohm) .
Here is what I've come up with,,, I uninstalled C8(B?) from the Hi pass filter and reversed The polarity of C1 the input capacitor,,, Guess what?? The Oscillation totally stopped, Yaaaaaaaay,,,,,
I have one more question if I may,,, Do I really need to install the 2000uF capacitor on the output to go into the speaker? Aaaaaaaaaaaaand what happens if it is not installed? I realize that it is there to block the DC from hitting the Voice coil but,,??
Quote from: TK on September 27, 2017, 10:24:55 PM
I have one more question if I may,,, Do I really need to install the 2000uF capacitor on the output to go into the speaker? Aaaaaaaaaaaaand what happens if it is not installed? I realize that it is there to block the DC from hitting the Voice coil but,,??
YES tiss there to block the DC which will burn out the voice coil,,,, but If you just can't accept the science,, feel free to try it ;)
A cap at that point has the advantage of being a point where you can tailor the freq response a bit,,smaller values will wipe off excess bass if needed.
Phil.
Hi Phil,, How will or does it burn out the voice coil? :)
"How does a dc voltage burn out a voice coil"?
Heat.
Yes, heat.
In this case, the heat is a result of the power going to the speaker. Voltage squared, divided by the resistance of the voice coil.
Why does the power from DC burn the coil, when AC voltage usually does not?
DC is constant polarity, so the coil sits in place. The usual heatsinking of the magnet and polepiece when the coil is moving from AC does not take place.
Often the DC is even big enough to push part of the coil out of the gap, and that part will burn first.
Quote from: g1 on September 29, 2017, 01:37:22 PM
Yes, heat.
In this case, the heat is a result of the power going to the speaker. Voltage squared, divided by the resistance of the voice coil.
Why does the power from DC burn the coil, when AC voltage usually does not?
DC is constant polarity, so the coil sits in place. The usual heatsinking of the magnet and polepiece when the coil is moving from AC does not take place.
Often the DC is even big enough to push part of the coil out of the gap, and that part will burn first.
Fresh voice coil on right, burnt on left.
Notice the back area looks almost normal (it stayed inside the gap), but forward one which was pushed out (speaker cone pushed forward by positive DC) is toasted:
(http://www.speaker-doctor.com/Gallery_files/Media/DSC00006/thumb.jpg)
same but higher power amplifier involved:
(http://sound.whsites.net/articles/spk-fail-f6.jpg)
notice burned glue and insulation and wire on its own travelled even forward.
Ah, I get it,, That's crappy for sure... will place the cap in the positive side of the chip output..... Thanks you guys.
Understand that the reason for the capacitor on the output is because the power supply is a single polarity.
Therefore the output will 'sit' at 1/2 of the supply voltage.
Which is Volts dc.
The cap is not needed on a dual supply because the output 'sits' at 0 Vdc.
Very strange indeed. This is my first experience with these chips, so learning an amazing amount about them for sure... I've blown 2 of them up,, which is very frustrating for sure.. Had the last one wired up and everything was correct.. Voltage from the tl-072 was finally working and before I put it in the Chassis it worked,, after that nothing,, Crappy,, LOL,,, No output,, going to try another TDA2030,, Not sure if the issue was static or overheating or just being played with too much,,, Checked the temp with my lazer and it got hot but still under the radar,,, I'll take the dead chip out an install a new one and see what happens,,, Thanks for your Help.. Really super appreciated it for sure..
Q do you have the 2030 mounted on a heat sink? If so is it electrically isolated from the heat sink. The tab is not ground so you always check that it's not shorted to chassis before you apply power.
Phil.
Hi Phil,, Yes I do,,, I found the problem when I went to replace the chip,,, It was a Broken Pin 4,, Snapped right off,, I'm going to have to find a way to support the Heat sink,,, It keeps flopping back and forth and broke the pin off,, Dang,, so close to getting this working,, LOL,,,, Are you talking about the Metal tab that is the back of the 2030,,, I always thought that was tied into ground and connected on the inside to pins 3 ?
I would have to question where you purchased the TDA2030 ic's.
That ic is no longer in production.
LM1875 is.
May be wrong but I think TDA2050 is the dropped out one and 2030 is still in the race.
Anyway, browsing through Mouser/Digikey/Farnell will clear the doubt.
Quote from: TK on October 04, 2017, 03:02:52 PM
Hi Phil,, Yes I do,,, I found the problem when I went to replace the chip,,, It was a Broken Pin 4,, Snapped right off,, I'm going to have to find a way to support the Heat sink,,, It keeps flopping back and forth and broke the pin off,, Dang,, so close to getting this working,, LOL,,,, Are you talking about the Metal tab that is the back of the 2030,,, I always thought that was tied into ground and connected on the inside to pins 3 ?
Pin 3 is the negative supply (and having just checked) IF using single supply it becomes circuit common (ground) so it does not need to be isolated,,,,BUT when using split supply rails that tab is at negative voltage and with no isolator it would cause a dead short.
(just sayin,,so you know for future builds :tu:)
Yes you need to mount the pcb to the heat sink otherwise you will break the lead wires. 8|
Phil.
I bought them from a friend of mine who bought them when they were still in production.. I think he said he had 100 of them or so,,, I bought 10,, and good thing,, LOL,,,
I built an epoxy support for the chip and it is mounted to a Heat sink,, it's waaaaay better now,,,
Every thing is installed and now will amplify a guitar signal,, Sounds crappy but I'll have to re bias the tl-072 because i had to put in a voltage divider to drop some of the voltage to the op amp,,, Just keep going round and round,, but getting closer... :)
Not sure about the 2050's but for sure the 2030 are obsolete. I have bought a LM 1876 chip for later on. Gotta say,, sure am learning alot here. Thank you guys.