NO! not again....

[Audiophilenoob]

I received my 0.004" mica in the post today and I took it out and cut a piece and put it behind the LM4780 chip that I FINALLY got to work two days ago

It worked fine... no light bulb on. outputs hooked up and input hooked up

then I turned it off started on the other one... but before I did I turned it back on to make sure connections were correct...

now the lights on... ALWAYS.... 100w bulb FULLY LIT

I removed the amp from the heatsink again and STILL it's doing it!!

I check my connections nothings wrong! I removed the outputs (this is the only thing I changed from before)... STILL IT"S DOING IT!

it was working so good the other day with the outputs running strong iwth musical input... everything is testing correct on the voltages even the input when music is sent through. But the 100w bulb is FULLY lit at idle and the amp isn't playing music again!

I tried it on another board... SAME THING!!!!

GAH FOR THE LOVE OF GOD!!

 

[Audiophilenoob]

I know this amp shouldn't be this hard to build....

this is ridiculous!!!

I'm really just about to dump this entire effort and all these boards into the garbage

I can not for the life of me get that board to do what it did earlier... I removed all the wires but the DC mains to the amp board and it STILL has that damn light on full blast... I'm about to just remove the light from in line just to see if for some inane reason it's doing this to just **** me off!

Screw it if it blows another chip!!!!!!!!!!!!!!!

 

[Stocker]

Put it aside for a week or two

and if it still goes to the trash, send it all to me instead!

 

[Audiophilenoob]

Put it aside for a week or two

and if it still goes to the trash, send it all to me instead!

it's getting sent to my good friend in cali who's been troubleshooting amps and such since before I was born

.... sry no free amps... though an hour ago you MIGHT have gotten it

 

[Stocker]

Ho well, that's what I get for actually *working* at work until a good stopping point comes along...

 

[cowanrg]

I know this amp shouldn't be this hard to build....

this is ridiculous!!!

I'm really just about to dump this entire effort and all these boards into the garbage

I can not for the life of me get that board to do what it did earlier... I removed all the wires but the DC mains to the amp board and it STILL has that damn light on full blast... I'm about to just remove the light from in line just to see if for some inane reason it's doing this to just **** me off!

Screw it if it blows another chip!!!!!!!!!!!!!!!

i feel your pain! ive been troubleshooting my preamp for 3 months now.

 

[Audiophilenoob]

i feel your pain! ive been troubleshooting my preamp for 3 months now.

Hopefully my incredibly good friend and his 20+ years troubleshooting will find the problem

what a great guy!

 

[wes-ninja250]

If the bulb is on full blast, you've probably got a dead short or the amp is oscillating like mad.

Are your input and output leads well separated?

Pause, measure, check, think. The bulb is telling you that there is a big problem. Removing the bulb from the circuit will only make the chip use MORE power. And we all know where that leads.

Wes

 

[Audiophilenoob]

Are your input and output leads well separated?

6 feet apart enough???

 

[demogorgon]

I havn't been diy'ing for long, but i can give you a tip for future projects:

use extra soldering flux
use pcb cleaner or etanohl and a toothbrush to clean off the nastities that may hide in places unknown. brush thoroughly.

built myself a nice litle lm4780 amp with used parts from a friend who felt like you did. it workes like a charm.the amp wasn't hard to do either, as you say. just take the time needed and then some.

my 2 cents
marius

 

[cowanrg]

i had a dead short in my preamp when i first started with all the problems.

the solution? taking the entire thing apart, using new wires and rebuilding it. turned out i had the secondaries wired wrong. there is nothing quite like taking it all apart and putting it back together again.