t-amp modding trouble - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

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 7th March 2006, 08:25 AM   #1
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Default t-amp modding trouble

Hi all,


OK, I think I've done some damage to my t-amp. The plane here was to use 2 t-amps to bi-amp. First t-amp is lightly modded, reboxed and replaced the input capacitors (C3,C4) with 2.2uF audio grade ones.

I received the second t-amp today, set to work reboxing it. Eventually I got the new input capacitors on and connected (not an easy job for someone with my skills) the amp ran AOK for about 2 mins and then cut out. Opened up the box, found that the chip is getting hot if the power is turned on. If you let it cool, still no sound. No signs of burning on the board, scorch marks etc etc etc.

Have I irreparably damaged the board? Anything I should try to salvage it?

Many thanks in advance,
Fran
  Reply With Quote
Old 7th March 2006, 10:24 AM   #2
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Hi again,

Also, before I go an do this again (when I can summon up the heart to do it!) do you guys think it would be OK to leave the SMT C3 and C4 in place and just add the extra capacitors. This would be easier to solder.


Fran
  Reply With Quote
Old 7th March 2006, 12:47 PM   #3
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Kona, Hawaii
Blog Entries: 4
If the chip is getting hot you may have the outputs shorted to ground somehow. None of the speaker terminals can be connected to ground. Check that.

Also, it is possible that you have caused a DC offset with your inputs mods, happens all the time. There are plenty of discussions of this on the forum. Check the outputs with a volt meter. If you find more than 0.2 volts DC between + and -, then you have a problem.
__________________
Take the Speaker Voltage Test!
  Reply With Quote
Old 7th March 2006, 08:21 PM   #4
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
OK, checked outputs every way I could for continuity and all checked out OK.


Then I tried what you said about the DC offset. I get about 3V on one channel and 5 on the other. The chip heats up over maybe 2 mins. Also, I only get sound on one channel, the other channel is ver faint.

Any suggestions welcome and I'll go and search the forum for this topic too.


thanks for the help,

Fran
  Reply With Quote
Old 7th March 2006, 10:47 PM   #5
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
OK,

I think I may have found the trouble. I reckon I've damaged the pad around C4 - right above where C4 is written. If I leave this disconnected I get a DC reading of <10mV. So obviously my desoldering of C4 has led me to this trouble, and now after all the poking, the pad beside the C4 label is gone too.

Would anyone know where else on the board I could solder the jumper to my replacement C4 cap? The trace just seems to disappear - perhaps to the other side of the board?

Thanks (again) in advance
Fran
  Reply With Quote
Old 9th March 2006, 09:18 AM   #6
jkeny is offline jkeny  Ireland
Banned
 
Join Date: Feb 2007
Location: Dublin
Fran,

Have you looked at Panomaniac's site - http://www.michael.mardis.com/sonic/start.html

I think this gives all the input mod options.

If you look at the schematic, even if you have destroyed the pads around C4, You could still connect a cap between end of L2 & beginning of R2.

If you can't hack it give me a shout - are you in Dublin?

John
  Reply With Quote
Old 9th March 2006, 04:59 PM   #7
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Hi John,

yes, well just outside, I'm out near naas. Would you email me at woodturner-fran AT oceanfree DOT net and I'll get back to you.



Thanks,

Fran
  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
NAD PP1 modding, psu and others Psychobiker Analogue Source 6 15th June 2009 09:39 PM
Modding a GDA-700 ben62670 Digital Source 2 22nd August 2008 02:53 AM


New To Site? Need Help?

All times are GMT. The time now is 03:59 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