Replacement for TDA1112 audio IC for CRT TV
Good day folks. I wrote about this in the past, but never actually got a clear answer. I don't blame anyone, since the problem is rather generic and I myself wasn't too sure what could be causing it in order to narrow it down for people to provide more specific help, so in the meantime I did some troubleshooting on my own which hopefully narrowed the issue down enough to get some tips on what I'm trying to accomplish.
To recap: I got a CRT TV (that right there might also be enough to put people off) which has a buzzing sound on the internal speakers which reacts to the image being displayed. The noise appears as soon as the volume is raised to 1 and goes away when set to 0 or muted. It doesn't grow louder with the volume though, so at a normal listening level it's almost inaudible unless you know about it. That's what I wrote in my original post, so there's no way you'd be able to pinpoint what's wrong, since there are A LOT of things that can cause this.
Now: I first tried changing the SAW filter. This was pointless because the buzz is present on the AV input also, so it's not the tuner that's causing it. I then checked to see if the noise is present on the line outputs at the back: it's not - connecting the audio outputs to an external amplifier produces clear sound, so this narrowed it down even further to the amplifier IC. I replaced a bunch of caps around it, but that didn't help either - the buzz is still there, so at this point I'm pretty sure it's the amp IC itself, which brings me to my actual question: it's a TDA1112....I COULD NOT find anything about this IC, let alone find a place to buy it locally, so taking a closer look at the schematic made me pretty confident that I'd be able to install any other audio amplifier. I've included a snippet of the schematic showing the area of interest: all there is is SIGNAL IN A, SIGNAL IN B, VCC, GND, OUT A, OUT B and MUTE....I'm sure we can find those pins on other ICs as well. There are two more pins which I don't what they do: CIV and RR, but I see those just have caps on them. So what would be a good and easy to find 10w or less audio amp to hack in there ? It would have to run on 20v single rail and have a MUTE pin...any thoughts ? Cheers.
To recap: I got a CRT TV (that right there might also be enough to put people off) which has a buzzing sound on the internal speakers which reacts to the image being displayed. The noise appears as soon as the volume is raised to 1 and goes away when set to 0 or muted. It doesn't grow louder with the volume though, so at a normal listening level it's almost inaudible unless you know about it. That's what I wrote in my original post, so there's no way you'd be able to pinpoint what's wrong, since there are A LOT of things that can cause this.
Now: I first tried changing the SAW filter. This was pointless because the buzz is present on the AV input also, so it's not the tuner that's causing it. I then checked to see if the noise is present on the line outputs at the back: it's not - connecting the audio outputs to an external amplifier produces clear sound, so this narrowed it down even further to the amplifier IC. I replaced a bunch of caps around it, but that didn't help either - the buzz is still there, so at this point I'm pretty sure it's the amp IC itself, which brings me to my actual question: it's a TDA1112....I COULD NOT find anything about this IC, let alone find a place to buy it locally, so taking a closer look at the schematic made me pretty confident that I'd be able to install any other audio amplifier. I've included a snippet of the schematic showing the area of interest: all there is is SIGNAL IN A, SIGNAL IN B, VCC, GND, OUT A, OUT B and MUTE....I'm sure we can find those pins on other ICs as well. There are two more pins which I don't what they do: CIV and RR, but I see those just have caps on them. So what would be a good and easy to find 10w or less audio amp to hack in there ? It would have to run on 20v single rail and have a MUTE pin...any thoughts ? Cheers.
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