lm4780 problem lm4780 problem - diyAudio
Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

lm4780 problem
lm4780 problem
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 3rd June 2007, 02:29 AM   #1
Jim Karr is offline Jim Karr  United States
diyAudio Member
 
Join Date: May 2004
Location: Southwest Michigan
Default lm4780 problem

I've assembled one of BrianGT's LM4780 boards. Turned on the power, no smoke (praise the Lord). No signal from the speakers, just a very infinitesimally small hum. Apparently it's in protection of some sort.

I don't know what voltages and other measurements I should be getting on each pin out. Anyone have any ideas?

No solder bridges, and I've checked my connections several times. It all looks correct. Help?
__________________
As for me and my household, we shall serve the Lord. Joshua
  Reply With Quote
Old 3rd June 2007, 06:32 AM   #2
YFW is offline YFW  United States
Account Disabled
 
Join Date: Jun 2007
Please check the output DC voltage which should be very low if everything is in normal condition.
  Reply With Quote
Old 3rd June 2007, 01:22 PM   #3
jackinnj is offline jackinnj  United States
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
lm4780 problem
Default Re: lm4780 problem

Quote:
Originally posted by Jim Karr
I've assembled one of BrianGT's LM4780 boards. Turned on the power, no smoke (praise the Lord). No signal from the speakers, just a very infinitesimally small hum. Apparently it's in protection of some sort.

I don't know what voltages and other measurements I should be getting on each pin out. Anyone have any ideas?

No solder bridges, and I've checked my connections several times. It all looks correct. Help?

How have you connected the MUTE pin?
  Reply With Quote
Old 8th June 2007, 10:18 PM   #4
Jim Karr is offline Jim Karr  United States
diyAudio Member
 
Join Date: May 2004
Location: Southwest Michigan
DC voltage is almost nonexistent. It's been so long since I worked on this amp I don't remember the exact value, but I do remember that it was miniscule.

I believe the mute pin is just fed through the board into a plain unclad hole, so it is not connected at all.

Thanks for your responses!
__________________
As for me and my household, we shall serve the Lord. Joshua
  Reply With Quote
Old 9th June 2007, 12:38 AM   #5
jackinnj is offline jackinnj  United States
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
lm4780 problem
Quote:
Originally posted by Jim Karr
DC voltage is almost nonexistent. It's been so long since I worked on this amp I don't remember the exact value, but I do remember that it was miniscule.

I believe the mute pin is just fed through the board into a plain unclad hole, so it is not connected at all.

Thanks for your responses!
Well, ther you go...the mute of the LM4780 needs a few milliamps to turn the amplifier on...see the product PDF.
  Reply With Quote
Old 11th June 2007, 11:14 AM   #6
sangram is offline sangram  India
diyAudio Member
 
Join Date: Sep 2002
Location: India
On that particular board (at least the Peter Daniel version) there are two pads that look like surface mount pads on the 'copper' side of the board, where I solderded the mute resistor. It's not marked on the silkscreen, so it's easy to miss.
  Reply With Quote
Old 13th June 2007, 08:56 AM   #7
zei is offline zei  Sweden
diyAudio Member
 
Join Date: Feb 2005
Location: Gothenburg, Sweden
I did the same mistake
ie, i did not solder the MUTE resistor and i got no sound.

So follow sangram,s suggestion and you will have music in no time

/Z
__________________
Tala är tiga, silver är guld
  Reply With Quote

Reply


lm4780 problemHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Problem with LM4780 Cyberzim Chip Amps 14 24th January 2010 05:40 PM
LM4780 problem - need Help AndriyOL Chip Amps 56 29th January 2009 07:58 PM
LM4780 problem Lamicz Chip Amps 6 6th November 2005 01:50 AM
LM4780 problem Faber Chip Amps 8 16th August 2004 04:39 PM


New To Site? Need Help?

All times are GMT. The time now is 08:57 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki