lm3886 not working

[SISKO]

hi, all
        well a week ago i made the lm3886 amp @ ggg.
it ran perfectly.. but yesterday i came from holydays and this baby do not want to fly anymore
when i touch the HOT in, it make the typical noise when you touch a guitar cable.. but when i touch both, ground and hot in, the noise just disappear..
any body knows?
could it be a low amp. transformer.?
or a bad heatsink?
thank you in advance

[ninoman123]

Its VERY hard to tell from what you told. How about some pictures of the board? A picture speaks 1000 words.

[Joecool85]

Yeah, pics and some specs.  As I'm finding out now, these babies take large heat sinks.  At least 1" tall fins, and at least 9" square area (IE- 3x3 or 2x4.5) and thats minimum, most people do double that!  Also, a large transformer is in order, minimum of 18 + 18 160va or so.  On my project that uses a lm4780 (which is two lm3886s in one chip) I'm going to be using a heatsink that is roughly 1" tall fins, and 3" x 8" for a total of 24 square inches of heatsink. 

[SISKO]

ok thanks guys...
it`s true, it`s hard from what i told..
anyway, when i guet the camera i`ll post som pics.
right now i`m thinking about if i could damage the chip.
my situation was. (i guess): having a low amp. transformer, i wanted more volume, but i couldn`t get enouhg ,so, i plug the distortion and turn the LEVEL too high (couse i did it ) and burnt the chip.
that make sence?
anibody knows what the maximun voltage capability?
finillaly, could i have some voltage reading?
thanks a lot in advance 

[RDV]

ok thanks guys...
it`s true, it`s hard from what i told..
anyway, when i guet the camera i`ll post som pics.
right now i`m thinking about if i could damage the chip.
my situation was. (i guess): having a low amp. transformer, i wanted more volume, but i couldn`t get enouhg ,so, i plug the distortion and turn the LEVEL too high (couse i did it ) and burnt the chip.
that make sence?
anibody knows what the maximun voltage capability?
finillaly, could i have some voltage reading?
thanks a lot in advance 

We don't know what transformer you used.
We don't know what type of power supply you used.
We don't know which version of the chip you used.
We don't know how big your heatsink was.
Nothing.

If you can't tell us any of that we can't help you.

RDV

[R.G.]

There's a sticky at the top of the list of postings called "What to do when it doesn't work".

Could you read that and post the appropriate information back here?

The posting was designed to get the correct information to allow us to diagnose problems remotely.

[SISKO]

ok  thanks you guys..
you have the true..
i may have gone out of my way
anyway... thanks.. a lot.. i´m sometimes a litte despistado...
i just wanted to know if that was a NORMAL problem... but i should advice you..
OK anyway.. thanks
bye

[SISKO]

thanksans R:G. i should read it..
any way.. if you can help me ....thanks for your patience...
here we go again:
well i built the lm3886 from ggg..
http://www.generalguitargadgets.com/pdf/ggg_lm3886_amp.pdf
i followed closely the project.. all components of the right value. the PS is the bipolar supply at ggg http://www.generalguitargadgets.com/pdf/ggg_bipolar_ps.pdf
What it does and does not do well i have already said that
i didn't substituted any part..
voltage reading... i´ll post it tomorrow..
i used  a transformere of an old videoplayer.. but I'm gonna get a 18+18 x 160VA
ok thanks for your largeeeeeeeeeeeeeeeeeee patience
(and for teaching)