lm4780 amp not working

[rs1026]

I am not getting any sound but the heat sink is getting hot within few minutes.Could there be a short somewhere??

[Vikash]

check all your wiring and components thoroughly!

[Roushon]

possibly short circuit at output stage.....

[carlmart]

If you using a double-sided pcb, have a careful look at every solder pad on the ground plane side to see if there is any solder shorting anything.



Carlos

[rs1026]

I am using a single sided pcb based on ukram's design.The pcb looked quite ok but some how i guess there was a short somewhere.i tried locating it through continuity testing but was unable to do it.So I thought of replacing the chip but couldnt desolder the chip properly the pcb tracks started coming out.I was put off by all this stuff so i trashed the pcb and the chip

But I have few more chips I personally feel lm4780 pcbs are not diyable.Hence I like lm3886 when it comes to this issue.

[Lsharptec1]

Any project is diyable to a resourceful DIYer. Experience tells us that often it is the simplest of things that cause problems like the one you are having.

Larry

[hilbren]

check the mute function

[juggle2]

I'm having the same problem...no sound, nothing.

BGT kit, dual/mono...checked connections- everything looks good. i think if it's a simple bad soldering connection one channel might work.

Assembled as per "garbage" post here. chipamp lm4780 components


but on the pcb i'm not sure which goes where as there is no documentation yet.

can someone confirm the below?

i gather the following information from other threads:
R1 = 22k (feedback resistors)
R2 = 22k (feedback resistors)
R3 = 1k or 680R (for more gain)
R4 = 22k
R5 = 1k or 680R (for more gain)
R6 = 1k or 220R (series input resistors)
R7 = 1k or 220R (series input resistors)
R8 = 0.1R (output)
R9 = 0.1R (output)
Cz1 and Cz2 seems to be the zobel cap.
the holes parallel to Cz1 and Cz2 seems to be the zobel resistors.
C1 and C2 are the 10uF bypass caps or BG 4.7uF N caps.

Could someone elaborate on how to check mute function?

[juggle2]

Oops, not the same problem...power to the amp board, but the chip's not hot.

[x. onasis]

Any project is diyable to a resourceful DIYer. Experience tells us that often it is the simplest of things that cause problems like the one you are having.

Yes, the problem is often very simple, once you find it.

Brian's instructions for the 3875 kit are pretty thorough, but almost nonexistant for the 4785. Does anyone have pics of their finished 4785 kits, or have advice to share about the differences in building the two?

Are non-conductive mounting bolts or washers necessary between the chip and heatsink?