need tda7240 guitar amp schematic

[Jdansti]

That doesn't sound too bad if it were in the US, but hopefully it didn't affect your budget too much.

[jogina111]

ok, I built the TG but  it sounded like an arriving ferry. It hums like a giant.. What could be wrong, Im sure the components are in correct places.

[Jdansti]

It could be your power supply. As a test, take the largest electrolytic cap you have and just hold it in your fingers and put the + lead on the +12v pad and the (-)lead on the negative pad and see if that helps. If it does, I'll tell you where you can solder it permanently.

[jogina111]

it didnt helped...

[jogina111]

it didnt helped a lot. The humming is still too loud and .. The 2200uf cap eases it like 10%

[Jdansti]

Can you temporarily hook the power up to a 12V car battery and see if the hum goes away?

[jogina111]

if a power supplx is noisy, could it be on the transformer or the filter? Im looking on building a power supply..

[Jdansti]

I'm not an expert on power supplies, but my guess is that you need more filtering.

The thing to watch out for, whether you add a filter to your current PSU, or you build one, is the TG could potentially draw 1-3 amps depending on the PSU voltage.  You need to make sure your caps, resistors, and diodes in your filter are rated properly to avoid frying them.

To reiterate what several of us have said, building a PSU from scratch is potentially a deadly act, especially for noobs. Hopefully someone can give you some guidance on filtering your factory-built PSU. It might be as simple as building a beefed up Huminator that can handle the current draw of the TG.

[jogina111]

I connected my guitar to the tg and the hum dissappeared and its really a good amp.. But when my guitar is removed, it hums loudly again...is that normal?

[Jdansti]

I believe that most amps hum when there isn't a complete circuit at the input (no instrument plugged in).  I know that my amps do.  This usually isn't a problem because there's no reason to crank up the amp when there's no instrument plugged in.

Glad you got it going. Is it loud?     If someone has told you to turn it down, it should be loud enough.

[jogina111]

yeah, its pretty loud...my brother and sister came shouting at me to turn it down...haha i thinks its done... I just need a better power supply and use some of the parts you  sent me to build an overdrive channel..

[Jdansti]

Cool!  On to the next project! 

[jogina111]

just cant decide on what to build next..

[jogina111]

just cant decide on what to build next..

[Jdansti]

How about an echo?

[Jdansti]

How about an echo?

[jogina111]

thats pretty complex...Im thinking of a booster, distortion, compressor and /or reverb.

[jogina111]

thats pretty complex...Im thinking of a booster, distortion, compressor and /or reverb.

[Seljer]

I believe that most amps hum when there isn't a complete circuit at the input (no instrument plugged in).  I know that my amps do.  This usually isn't a problem because there's no reason to crank up the amp when there's no instrument plugged in.

Glad you got it going. Is it loud?     If someone has told you to turn it down, it should be loud enough.

Most commerical amps use switching jacks to ground the input if there isn't any 1/4" plug inserted (though the silence doesn't apply if a cable is plugged in without a gutiar at the other end)