MTX 4160 and DC power supply interaction - diyAudio
Go Back   Home > Forums > General Interest > Car Audio
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 12th October 2007, 02:10 PM   #1
ECM is offline ECM  United States
diyAudio Member
Join Date: Jul 2004
Location: Dubai
Default MTX 4160 and DC power supply interaction

I recently replaced some bad components in an MTX 4160 amplifier. Two power supply fets, two burned out gate resistors, and two shorted BUZ11 outputs.

After all was changed, I went to power it up and my DC power supply started kicking out all sorts of voltage! This is a new power supply that was given to me and it has variable DC and AC ouputs at 5 amps. It's made by Alpha Magnetics, but I cannot find much info online about it.

Anyway, as soon as the DC power supply sees a capacitive load, the voltage starts ramping up. If I disconnect the amp and use a resistor dummy load, it works great, voltage is stable. I opened it up and it appears to be a triac controlled unit with a heftly transformer.

I decided to bypass the DC circuitry and I built my own MUR860 rectifier and used the AC ouputs. All is well, voltage is good, UNTIL I connect the amp! Is it possible the amplifier is somehow causing the power supply to malfunction?

I took some voltage readings and with the AC voltage at 5 volts I somehow manage to get over 20V DC on the other side of the rectifier with the amplfier connected. Don't ask me how this happens, I am STUMPED!

I "pulse width modulated" the darn thing by turning it on and off really fast while monitoring the multi-meter and the amplfier turns on between 11-14 or so volts. It seems the amp is working, but my power supply isn't.
  Reply With Quote
Old 12th October 2007, 03:16 PM   #2
diyAudio Member
Join Date: Nov 2003
Location: Louisiana
What happens if you connect both the dummy load AND the amplifier to the supply? If the output is not happy with the amp as a load, maybe the resistor will help lower the overall reactance and the supply will work properly.

You may also want to try connecting a diode in series with the DC output to see if the high voltage is coming from the supply or if it's only on the amplifier side of the diode.

You could try connecting the amp to a battery. Do so via a 10 amp fuse in case there is an unknown fault in the amp. Clamp the FETs to the sink before applying power.
  Reply With Quote
Old 12th October 2007, 05:50 PM   #3
ECM is offline ECM  United States
diyAudio Member
Join Date: Jul 2004
Location: Dubai
I did indeed connect the amp with the dummy load, but it still didn't like it. The dummy load is a 1K 10 watt resistor. I'm going to lower that to maybe 100 or even 50 ohms.

I will also try an inline diode and see what it does.

The next few days are busy so it might be a week before I try it, but that will give me some time to think about it some more.

thanks for the tips Perry.
  Reply With Quote
Old 12th October 2007, 06:46 PM   #4
diyAudio Member
Join Date: Nov 2003
Location: Louisiana
When you said dummy load, I was thinking audio dummy load (4-8 ohms).
  Reply With Quote


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
MTX Thunder 4160 Repair ECM Car Audio 2 19th November 2007 10:55 AM
loudspeakers and room interaction jlo Multi-Way 1 25th July 2007 08:17 PM
Amp-Load interaction zeus_threat Solid State 26 18th June 2006 06:43 PM
Aleph CS and interaction with PS mchapman Pass Labs 2 5th June 2006 08:46 PM
Magnet interaction?? (Car Audio) WhtCastle Everything Else 1 26th January 2002 02:24 AM

New To Site? Need Help?

All times are GMT. The time now is 12:16 AM.

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

Content Relevant URLs by vBSEO 3.3.2