Modified Crown 5000VZ - Help!! |
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pczjm
Registered User Joined: 07 November 2016 Location: Nottingham, UK Status: Offline Points: 46 |
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Posted: 11 July 2017 at 10:17pm |
Hi Guys,
I have a Crown Macro-Tech 5000VZ that was previously used as an amplifier for an NMR machine (similar to MRI) in the chemistry department where I work. It has apparently been modified to some extent for this purpose. The obvious thing is that the gain pots have been removed from the front but other than this I am clueless as to how it may have been modified. I popped the top, but never having studied the internals of an amplifier before, this was less than illuminating! There was no obvious/major difference to the pictures I found on the internet of the same model. Does anyone out there have experience of this kinda thing? As you might of guessed I wanna use it to power bass bins but am sure if I would need to "convert it back" to any extent. |
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pczjm
Registered User Joined: 07 November 2016 Location: Nottingham, UK Status: Offline Points: 46 |
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Here's some pics:
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pczjm
Registered User Joined: 07 November 2016 Location: Nottingham, UK Status: Offline Points: 46 |
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Dub Specialist Sound
Old Croc Joined: 15 November 2013 Location: Smethwick Status: Offline Points: 4873 |
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You need to get in touch with
DjLeco forum member on here, ent seen him for quite a while tho hes a don with them, and amps in general
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Musical Roots Reggae Vibration is Life! for music is sound...sound is vibration...vibration is energy... and energy begets life. Therein lies my passion!...MUSIC IS LIFE...
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kedwardsleisure
Old Croc Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4938 |
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the front pots are connected to the rear board via a pair of screened grey cables, they fit at the back on either a 3 or 4 pin header depending on age. For the amp to work, there may be a jumper, resistor or preset pot fitted on these headers instead. Take a close up picture of the rear board if you're not sure and post it here.
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Kevin
North Staffordshire |
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kedwardsleisure
Old Croc Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4938 |
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ok, found a suitable pic.
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Kevin
North Staffordshire |
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pczjm
Registered User Joined: 07 November 2016 Location: Nottingham, UK Status: Offline Points: 46 |
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Thanks for the replies!! I'll have a proper look tomorrow at work but the best pic I've got atm is this one, I can't see the grey cables!
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DjLeco
Young Croc Joined: 21 April 2009 Location: Bucharest Status: Offline Points: 817 |
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Please give me the pictures at original size on mail
claudiu971@ yahoo(dot)com On last picture, I see no gray cables for volume potentiometer(s), is missing, maybe potentiometers too. Make one as mr. kedwardsleisure put above, to see exactly if missing or not potentiometers and cables with connector too.
Edited by DjLeco - 12 July 2017 at 12:06am |
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I'm A Stupid SMART Romanian...
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pczjm
Registered User Joined: 07 November 2016 Location: Nottingham, UK Status: Offline Points: 46 |
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Hi Guys,
Thanks very much, hope this photo is better: |
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studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
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It's likely the modification involves DC coupling the output stage, the NMR machine would have required very low-frequency high-current signals with DC components to drive large electromagnet coils.
I remember using them as an undergrad to determine the structures of molecules, they are eldritch high magick indeed ;) This will probably mean the speaker protection circuitry has been modified or disabled, because in normal audio operation any DC at the output is a fault. There was an industrial version of this amp (branded Amcron not Crown) that had a switch to select DC coupled or AC coupled (audio) mode. That may indicate that the modification is quite trivial. I see a wire link installed where one of the volume pots was connected. I would hazard a guess that the amp is in parallel-mono or bridge mode with the gain fixed at maximum (in those modes the channel B gain pot does nothing, so wouldn't need to be connected at all). I also see an extra trim pot tacked onto the legs of an IC and held in place with hot glue, and a capacitor added in series with a resistor, those do not look like factory installations to me....
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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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DjLeco
Young Croc Joined: 21 April 2009 Location: Bucharest Status: Offline Points: 817 |
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You must redo to factory construction all those modifications.
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I'm A Stupid SMART Romanian...
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kedwardsleisure
Old Croc Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4938 |
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Looks like some of the capacitors have been linked out too. This could be serious!
Oh and the optical compression components are missing Edited by kedwardsleisure - 12 July 2017 at 4:51pm |
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Kevin
North Staffordshire |
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