P3A won't work - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 December 2003, 07:56 PM   #1
diyAudio Member
 
Join Date: Mar 2002
Location: Atlanta, GA
Send a message via AIM to Austin
Default P3A won't work

I just finished wiring up my P3A. I tested with the 22 ohm safety resistors in place of the fuses. The LED lights up and everything appears fine. The voltage at the output is less than 1V. However the resistors get VERY hot. The voltage drop accross the resistors is almost 22V! It is the same for every channel. They all read almost exactly the same drop accross the resistors. This led me to believe that I had put in a wrong component. I looked over everything very carefully, twice and found that the NPN and PNP's were switched at the outputs. I changed this and tested again. The voltage drop accross the safety resistors is still the same. The voltages provided by the power supply seem to be fine, so I'm guessing the problem is in the amp. Does anyone have any recommendations? Thanks in advance,

Austin
  Reply With Quote
Old 1st December 2003, 08:08 PM   #2
diyAudio Member
 
bigparsnip's Avatar
 
Join Date: Apr 2003
Location: Cambridge
Are you sure the output transistors are still ok? As if they are damaged they could be shorting out and dropping tthe supply voltage from one (or both) rails accross the output resistors.
  Reply With Quote
Old 1st December 2003, 08:24 PM   #3
HDTVman is offline HDTVman  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Chicago area
I think I'd check all of the transistors. If the outputs failed shorted, they could take out the drivers etc. Transistors don't like to have the voltage reversed.

Later BZ
__________________
What ever makes the tunes flow
  Reply With Quote
Old 1st December 2003, 08:42 PM   #4
tiroth is offline tiroth  United States
diyAudio Member
 
Join Date: Dec 2001
Location: Pittsburgh, PA, USA
Check the drivers first. (BD139/BD140)
  Reply With Quote
Old 3rd January 2004, 09:31 AM   #5
darkm4n is offline darkm4n  Romania
diyAudio Member
 
darkm4n's Avatar
 
Join Date: Aug 2003
Location: Bucharest
Send a message via ICQ to darkm4n Send a message via MSN to darkm4n Send a message via Yahoo to darkm4n
For shure you damage the output transistors ... they are shorted ..
  Reply With Quote
Old 3rd January 2004, 10:04 AM   #6
sss is offline sss  Israel
diyAudio Member
 
sss's Avatar
 
Join Date: Jul 2003
Location: Israel , haifa
Send a message via ICQ to sss
Quote:
Originally posted by darkm4n
For shure you damage the output transistors ... they are shorted ..
if u used the 22ohm resistors correctly then nothing should happen to the power transistors
  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
Would this work ? LesPaulStandard Instruments and Amps 3 4th May 2006 03:14 AM
Will This Work? sousmielie Class D 6 27th December 2005 06:53 PM
It Should Not Work ! f4bok Solid State 3 6th September 2004 06:33 PM
Would this work? JoeBob Solid State 5 18th July 2003 04:40 PM


New To Site? Need Help?

All times are GMT. The time now is 07:48 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