Xtant 3300c low output. - diyAudio
Go Back   Home > Forums > General Interest > Car Audio

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 28th February 2012, 03:17 PM   #1
diyAudio Member
 
Join Date: Jan 2012
Default Xtant 3300c low output.

ok... so years ago i got this amp in a trade knowing that some of the magic smoke had been let out of it.
life got busy an it was set aside.. a few months ago i pulled it out of the closet an pulled the cover off to find it had a bad cap... no big deal... replaced it, hooked it up and everything was good... nice sound very LOUD! been running it everyday no issues until yesterday... powered on just fine.. got maybe 20s into a song at low volume an then i heard two little thumps as if the amp was powering on or something and lost all but a lil volume... i can turn volume all the way up an can just be able to hear it.
nothing looks blown... i didnt smell anything bad.... no smoke..
i've seen a few threads on here where ppl are repairing this amp an was hoping someone could point me in the right direction.. maybe what/where to look on the amp... im not new to repairing electronics... but mostly it's just if i can see the damaged parts.

Any help on this would be greatly appreciated
  Reply With Quote
Old 29th February 2012, 01:58 AM   #2
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
There are several transistors marked J108 near the power amplifier section. What is the DC Voltage on leg 3 of those transistors?

Have you set the jumpers to provide the maximum gain?

Are the gain controls set to the maximum position?
  Reply With Quote
Old 29th February 2012, 02:12 AM   #3
diyAudio Member
 
Join Date: Jan 2012
ill check the volyage on those here in a bit..
an answer to the other question... yes ive tried the input gain jumpers in every setting an turned the gain knobs for left right an sub out.. they all function like there supposed to.. its just the audio coming out is like something you would here from a nice set of headphones a few inchs from your ears.. ive hooked up multiple things to it... same outcome everytime...
  Reply With Quote
Old 29th February 2012, 04:59 PM   #4
diyAudio Member
 
Join Date: Jan 2012
ok...
so i found 3 transistors marked j108.. i think.. really small print
wasn't to sure on what to set my meter on so i took to readings on each one on 20v setting an one on 200m setting.

listing 20v as first number
q37 0.05/53.0
q60 0.05/52.4
q87 0.05/52..5

an i don't know if it makes a diff or not.. but i don't have a power supply and i am doing all testing hooked up to my car battery.. car is not running
  Reply With Quote
Old 29th February 2012, 05:02 PM   #5
diyAudio Member
 
Join Date: Jan 2012
also i would like to thank you for trying to help me with this...
  Reply With Quote
Old 29th February 2012, 10:03 PM   #6
diyAudio Member
 
Join Date: Jan 2012
forgot to say that meter said negative voltage
  Reply With Quote
Old 1st March 2012, 03:55 AM   #7
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
The voltage should be near -15v.

Do you have positive and negative 15v on the power supply pins of the op-amps?
  Reply With Quote
Old 2nd March 2012, 12:19 AM   #8
diyAudio Member
 
Join Date: Jan 2012
ok... not sure what op amps those are.. but i found 9 of those lil guys on left side of the board...
number j2068d i think it said
not much diff in voltage on most of them
u22 both - an + on both sides - .04v
u23 same as above
u1 -.03 on both sides both pins
u6 -.04 on both sides both pins
u8 pin 5 +.08 pin 6 +.16 pins 2 an 3 -.04
u10 -.04 both sides both pins
u2 pin 2 .03 pin 3 .04 pin 5 .03 pin 6 .05
u4 pin 2 .05 pin 3 .04 pin 5 .02 pin 6 .03
u9 -.04 on both sides both pins
really hope those are the right ones...
seems like a long ways from 15v...
or im lookin at the wrong ones.. but i looked up all the lil chips on the board an those are the only op amps...

thanks for your time...
craig
  Reply With Quote
Old 2nd March 2012, 12:28 AM   #9
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Do you have voltage ranging from 25-45v on at least one leg of each of the output transistors? The output transistors are the ones with the large blue resistors in front of them. Do NOT let the probe short to the clamp (or to anything else) when measuring the voltage.
  Reply With Quote
Old 2nd March 2012, 12:40 AM   #10
diyAudio Member
 
Join Date: Jan 2012
does it matter which leg?
  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
Xtant 3300c No Output SR20DeDweeb Car Audio 6 10th January 2012 05:48 AM
Xtant 403A output fets brandes.cm Car Audio 3 29th March 2010 04:44 AM
xtant 3300c nath339 Car Audio 4 30th March 2008 03:50 AM
xtant 1001d low power Bgun Car Audio 0 22nd November 2006 06:50 AM
Please help - Xtant 1001DX with power but no output Supatech Car Audio 4 30th August 2005 08:54 AM


New To Site? Need Help?

All times are GMT. The time now is 11:46 AM.


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