Jump to content


Strange failure on AMCRON 5000VZ


  • Please log in to reply
8 replies to this topic

#1 DjLeco

DjLeco

    Power User

  • Members
  • PipPipPipPipPip
  • 60 posts

Posted 15 March 2013 - 11:54 AM

A friend of mine bought a Amcron 5000VZ with a channel (CH2) dead.
After opened and inspected, I saw what you see on pictures, foil connection between output module and binding post outpouts, shortcircuited and melted...

I have mounted new output devices MJ21193 and MJ21194 (carefully matched), I replaced burnt foil connection on both channels, with wires, with double isolation (thermocontractil tube above official wire isolation), recalibrated from manual service, the amp works FLAWLESS.

This is the first time when I fix of that kind of failure...

Posted Image

Posted Image

Posted Image

Posted Image

Posted Image

#2 DjLeco

DjLeco

    Power User

  • Members
  • PipPipPipPipPip
  • 60 posts

Posted 15 March 2013 - 11:55 AM

The GUILTY one... :

Posted Image

TESTS on dummy load:

8 Ohms:


4 Ohms:


2 Ohms:


#3 DjLeco

DjLeco

    Power User

  • Members
  • PipPipPipPipPip
  • 60 posts

Posted 15 March 2013 - 11:56 AM

Posted Image

Posted ImagePosted Image
Posted Image

Posted Image

#4 joust

joust

    Power User

  • Members
  • PipPipPipPipPip
  • 487 posts

Posted 18 March 2013 - 03:05 PM

I've seen a lot of output failures on an MA5K but this is the first time that I've seen the flex cable has melted like that! It must have been an output termination failure, you seem to mention that the output appeared short... This flex cable is quite expensive, if you were to order it from Crown, but quite reliable. By any chance, was the flex cable stuck or shorting with the chassis? It may cause such damage, but I would have thought the amp would shut down way before the cable would have burn through! Interesting...

Alain

#5 KGring

KGring

    Power User

  • Crown Staff
  • 84 posts

Posted 25 March 2013 - 08:47 AM

The flex bar is supposed to have an insulating sleeve around it. This was added to the design in 1994 as the vibration of the flex bar against the vents on the back panel will  eventually wear through the capton and short the bars to the chassis.
Kevin B. Gring
Crown Audio
kgring@crownintl.com

#6 joust

joust

    Power User

  • Members
  • PipPipPipPipPip
  • 487 posts

Posted 26 March 2013 - 03:43 PM

Kevin, have you seen this behavior before? Do you suspect that it could have been a 'pre-design fix' type flex bar?

#7 DjLeco

DjLeco

    Power User

  • Members
  • PipPipPipPipPip
  • 60 posts

Posted 02 May 2013 - 05:29 PM

The flexi cable was melted and open circuit in both of remaining parts.

It was just flexi cable failure, between foils, no one touched chassis or any other internal parts.

Could be an isolation failure, also for me, is the first time when I found that foil burnt...

It could happen, also after so much years of using.

Anyway, for me, the Macrotech 5000VZ is the most advanced class AB+B amplifier, ever made by Crown.

Oldschool, heavy like mountain, but very powerfull and nice-clean sound.

I fix  all of them with  happiness, because I love them!

If I was in USA (I'm Romanian), I already had repair shop oldschool CROWN amplifiers...

:rolleyes:

#8 joust

joust

    Power User

  • Members
  • PipPipPipPipPip
  • 487 posts

Posted 03 May 2013 - 09:52 AM

Great work! :D

Alain

#9 DjLeco

DjLeco

    Power User

  • Members
  • PipPipPipPipPip
  • 60 posts

Posted 03 May 2013 - 06:44 PM

Need one man (me) for working for Crown Service? :rolleyes:

I'm coming to USA!