MTX 6500D - No Output - Page 11 - 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 29th January 2011, 03:22 AM   #101
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Are there any solder bridges between the pads for the VCA?
  Reply With Quote
Old 29th January 2011, 03:34 AM   #102
diyAudio Member
 
Join Date: Mar 2007
Location: Columbus, Ohio ^
I did not think so; I cleaned the area up after removing it, but let me pull the board back out & look as accidents happen.
  Reply With Quote
Old 29th January 2011, 03:53 AM   #103
diyAudio Member
 
Join Date: Mar 2007
Location: Columbus, Ohio ^
I do not see any solder bridges & there are no direct shorts.

Pad 2 to pad 3 shows 100 ohms

Pad 2 to pad 4 shows 51 ohms

But no direct shorts anywhere.

And of course pin 2 & pin 6 are connected together. Those are the only somewhat low resistance readings I get on any of the pins & are possibly normal.
  Reply With Quote
Old 29th January 2011, 06:25 AM   #104
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
What's the DC voltage on pins 1 and 7 of that op-amp without the 1.2k resistor?
  Reply With Quote
Old 29th January 2011, 07:25 AM   #105
diyAudio Member
 
Join Date: Mar 2007
Location: Columbus, Ohio ^
With the 1.2K resistor lifted out of circuit:

Pin 1: -15.7vDC
Pin 7: -15.7vDC

The voltage on pin 1 & pin 7 slowly climb like some of my other readings, but it is really slow, if I let it sit there for a 4 maybe 5 minutes it would probably go up to -15.8v or a little more.
  Reply With Quote
Old 23rd May 2011, 02:54 AM   #106
diyAudio Member
 
Join Date: Mar 2007
Location: Columbus, Ohio ^
Thought I would get this amp back out & bump the thread. I figured I would wait a little while to post & let it sit to see how it was acting & see if it would still oscillate after sitting a while.

I still had the 1.2K resistor lifted (the one I put in place of the VCA) but I forgot, & it had no output. I opened it up & seen that it was lifted so I soldered it back in & it has output, but I know there are still some problems somewhere.

It has not stopped working / oscillating yet, I have had it playing music at a low level for over a half an hour. So it has been consistently playing & the audio sounds clean.

As posted back a couple pages, when I adjust the gain the speaker flutters / moves / pops real bad still.

When I adjust the FREQ adjustment it sort of flutters still too, but not as bad as the gain & less at the lower settings.

I still have yet to place an order for any parts, just have not been able to.

Anything else to check?

Thanks again for all the help.
  Reply With Quote
Old 23rd May 2011, 03:48 AM   #107
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Check the output pins of each of the op-amps to make sure that none have any excessive DC voltage on them. They should all be ~0v 0.05v.
  Reply With Quote
Old 25th May 2011, 06:49 AM   #108
diyAudio Member
 
Join Date: Mar 2007
Location: Columbus, Ohio ^
I pulled some of this from post #84, but re-measured the outputs of each op-amp again & noted it here (very close to what it was when last checked, most are definitely higher then 0.05v; op-amp F is the only one close to 0vDC, the rest are right around half a volt, not sure if that would be considered excessive, but a good possibility).

The op-amp I have labeled E still has -15vDC on both of its outputs. Pin 1 looks like it connects to D81 the case is marked D4. Pin 7 connects to D80 which appears to be marked D4 with a 2 right after that with a line above it, looks like D42, just the 2 has the line above it. It appears D80 & D81 are connected at the common leg of each package. The -15vDC is on both sides of D80 & D81, it is just slightly higher on the side not directly connected to the op-amps outputs.

For reference, below is the DC voltage on the output pins (pin-1 & pin-7) of the op-amps, using the ground terminal of the amp as my ground reference (gain at maximum, no RCAs or speakers connected):

Op-amp (A):
Pin 1: 0.585vDC
Pin 7: 0.716vDC

Op-amp (B):
Pin 1: 0.470vDC
Pin 7: 0.567vDC

Op-amp (C):
Pin 1: 0.469vDC
Pin 7: 0.467vDC

Op-amp (D):
Pin 1: 0.462vDC
Pin 7: 0.461vDC

Op-amp (E):
Pin 1: -15.61vDC
Pin 7: -15.61vDC

Op-amp (F):
Pin 1: 0.001vDC
Pin 7: 0.012vDC

Click the image to open in full size.
  Reply With Quote
Old 25th May 2011, 04:03 PM   #109
diyAudio Member
 
Join Date: Nov 2003
Location: Louisiana
Post the DC voltage on all of the pins of op-amp E.
  Reply With Quote
Old 25th May 2011, 09:35 PM   #110
diyAudio Member
 
Join Date: Mar 2007
Location: Columbus, Ohio ^
Here is the DC voltage on all of the pins of op-amp E.

Just to note again since its been a while, most of my voltage readings slowly climb as the amp sits on & some lower back down, so they may not be exact every time I check them, but it is always very close. Example: Pin 2 measured 0.389vDC when first checked, a couple minutes later measured 0.402vDC, then again a couple minute later it started to drop to around 0.36vDC, so not a huge change. I let it warm up for a minute then took the following readings.

Still very close to what it was in post #100 after op-amp E was changed.

Op-amp (E):
Pin 1: -15.7vDC
Pin 2: 0.402vDC
Pin 3: -5.07vDC
Pin 4: -16.91vDC
Pin 5: 0.401vDC
Pin 6: 5.96vDC
Pin 7: -15.7vDC
Pin 8: 18.56vDC
  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
MTX 6500d Parts weston_sagle Car Audio 19 21st September 2010 09:44 PM
MTX Thunder 6500D burnt ifrythings Car Audio 10 18th April 2008 06:35 AM
MTX Thunder 6500D does not power up tidom78 Car Audio 5 11th November 2006 07:36 PM
MTX 6500D repair bil Car Audio 3 29th May 2006 07:19 AM
I2S digital output in Marantz CD4000 and four TDA1541A with balance analog output iklari14 Digital Source 30 18th July 2003 01:57 PM


New To Site? Need Help?

All times are GMT. The time now is 09:41 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