Mute on BrianGT LM4780 PCB ? - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 1st April 2005, 08:53 AM   #1
AmA is offline AmA  France
diyAudio Member
 
Join Date: Feb 2005
Location: Lille
Default Mute on BrianGT LM4780 PCB ?

i buy the BrianGT LM4780 PCB and i don't understand how work the mute and how to make it . please help me. thanx
  Reply With Quote
Old 13th April 2005, 10:53 PM   #2
AmA is offline AmA  France
diyAudio Member
 
Join Date: Feb 2005
Location: Lille
Default Re: Mute on BrianGT LM4780 PCB ?

Quote:
Originally posted by AmA
i buy the BrianGT LM4780 PCB and i don't understand how work the mute and how to make it . please help me. thanx
does it work with or without the 10k resistor ? anybody ? please
  Reply With Quote
Old 13th April 2005, 11:13 PM   #3
AmA is offline AmA  France
diyAudio Member
 
Join Date: Feb 2005
Location: Lille
anyone ??
  Reply With Quote
Old 13th April 2005, 11:28 PM   #4
diyAudio Member
 
Join Date: Apr 2005
Location: In the Wild, Wild West
Is there a schematic for this amp? I am new to these boards. If you read the datasheet for the LM4780 found on National's site (www.national.com) it explains that Mute is controlled by current. If no current is pulled from the Mute pin then the IC will be in MUTE mode. So you should have a resistor from the MUTE pins to the negative supply rail to put it in PLAY mode.
  Reply With Quote
Old 13th April 2005, 11:46 PM   #5
lgreen is offline lgreen  United States
diyAudio Member
 
lgreen's Avatar
 
Join Date: May 2003
Location: San Diego, USA
Default Mute

The schematic is here, although its not very complete, doesn't include the power supply stuff for example, lacks pin numbers for the 4780, etc... Looking at it quickly, for example, I don't see an R8 and R9 (listed onmy board), and it has a RZ1 and RZ2 that are not indicated on my board. Maybe the R numbers correspond to the ones on the board, maybe not. They apparently have not had time to fully document this board, so it will require a little study, but you see that there is a 10K resistor from mute to the negative power supply. Put this in and good luck. Maybe reading the materials on the 3886 boards and 3875 boards will help.

Note- you need a 10K resistor or something close, because if you don't connect the mute pins to a negative voltage, you won't draw current from the mute pins, and this results in a mute condition.
  Reply With Quote
Old 14th April 2005, 07:28 AM   #6
bike is offline bike  United States
diyAudio Member
 
Join Date: Apr 2005
Location: calif
Default Lm4780 mute resistor

Brian sent me this picture because I had the same question. You need to put the mute resisitor at Rm. It is on the bottom of the PCB.
Attached Images
File Type: jpg 4780-resistors.jpg (78.5 KB, 732 views)
  Reply With Quote
Old 14th April 2005, 08:03 AM   #7
AmA is offline AmA  France
diyAudio Member
 
Join Date: Feb 2005
Location: Lille
Thanx very much for your help
  Reply With Quote
Old 14th April 2005, 04:08 PM   #8
diyAudio Member
 
Join Date: Apr 2005
Location: In the Wild, Wild West
That's the schematic for the amp? That is just the schematic from the LM4780 datasheet with some value changes and some caps removed. Intereting. Thanks for the link.

SL
  Reply With Quote
Old 15th May 2005, 08:51 PM   #9
diyAudio Member
 
Join Date: Feb 2004
Location: Mt. Pleasant SC
Default Re: Lm4780 mute resistor

Quote:
Originally posted by bike
Brian sent me this picture because I had the same question. You need to put the mute resisitor at Rm. It is on the bottom of the PCB.
Cr*p...I just ruined a board trying to put a resistor on these pads. I pulled the pad right off the board while I was trying position the resistor just a little bit better after soldering one side.

Now I'll have to get a whole new board try to remove all the components off the damaged board & try again. I might just forget the mute this time. Has anybody had problems without the mute?
  Reply With Quote
Old 15th May 2005, 09:20 PM   #10
diyAudio Member
 
RCBandwidth's Avatar
 
Join Date: May 2004
Location: New York and PA
Default Repair PC board

If you pulled a pad off the board,you should be able to repair it without resorting to a rebuild.I would not be too concerned about it.If you need guidance let me know. Bob C.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
paralleling 2 BrianGT lm4780 kits jimbo1968 Chip Amps 0 30th November 2005 05:34 PM
LOL.... I just fried 3 of my brianGT LM4780 boards Audiophilenoob Chip Amps 52 7th September 2005 01:59 AM
Just got my BrianGT LM4780 boards in and have a problem Audiophilenoob Chip Amps 4 29th July 2005 05:23 AM
BrianGT and Peter's lm4780 pcb boards rs1026 Chip Amps 0 25th August 2004 06:53 AM
LM4780, mute + microcontroller edpgc Chip Amps 12 19th August 2004 11:44 PM


New To Site? Need Help?

All times are GMT. The time now is 10:33 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2