Matchless hum ground noises !help!

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Matchless hum ground noises !help!

Postby midifx » Sat Nov 26, 2016 7:07 pm

Hi friends..
Last month i buyed an Amek Tac Matchless
With series 2000 power supply but when i put on the mixer a several hum is in all outputs,direct,monitor,tape,master and subs.
I trayed to get Schematics for the power 2000 series but i cant found.
Any have experince whit this problem? Or have the Schematics for the Matchless and the series 2000 power supply?
Thanks..
midifx
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Re: Matchless hum ground noises !help!

Postby jensenmann » Sun Nov 27, 2016 5:59 am

You can get the schematics from audiomaintenance.com
Did you try to disconnect everything except monitors to see if the desk itself hums or if it´s groundloops?
If the desk alone doesn´t hum then connect one after another everything to the desk. Then you should notice from which connection hum appears.
Is your hum 50/60Hz (EU/US) or 100/120Hz? If 50/60 Hz then it´s groundloops, if it´s 100/120Hz then it´s the desk itself/PSU.

A good starting point is to have the PSU reworked (recapped, etc...) anyway. A healthy PSU is the life insurance for your desk.
Jens
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Re: Matchless hum ground noises !help!

Postby midifx » Fri Dec 02, 2016 1:48 pm

Thank you..
So i have a troubble with the power unit.
.
I have buyed the Matchless but came with the 2000 series power unit in good condición but i saw that this power unit is bot the original for the Matchless and needs a trick or change in the pin conection is this true? Can you help ne with that?
Also came with the original power unit and i like to have ready the two power units.

Thanks..
Regards from México
midifx
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Re: Matchless hum ground noises !help!

Postby jensenmann » Sat Dec 03, 2016 4:09 am

A good place to start with is to completely recap the PSU. The 2000 PSU regulator cards have tantalum caps on the regulator outputs. These should be replaced with electrolytics with at least 10uF, better 100uF.
Tantalum caps turn resistive with age hence create a short across the voltage rail.
Another problem in 2000 PSUs can be the regulator sockets. They tend to get contact problems. Change these or solder the regulators and power transistors directly to the PCB.
Jens
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Re: Matchless hum ground noises !help!

Postby midifx » Sat Dec 03, 2016 2:31 pm

Thanks Jensennman..
Ill try to re check the power supply..
But now im confussed with the series 2000 ppower supply pins .. becuause i like to know if the series 2000 needs any other trick or bridge to cabe be used with the Matchless,the original has 4 pines and the 2000 series has more pines ..
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Re: Matchless hum ground noises !help!

Postby jensenmann » Sat Dec 03, 2016 3:10 pm

2000 PSUs were custom made for different desks, so yours may fit or not. Get a good tech to find out if it works on your desk. For a Matchless you´ll need only +/-17,5V rails and 48V phantom power. The other voltages available in a 2000 PSU are not necessary for your desk. Often the regulator boards were not even fitted. If it has an EP power outlet connector then you´ll need an adapter to 4Pin XLR which is as far as I know used in the Matchless as power inlet.
I cannot tell you what to do to convert it for being used with your desk without having it sitting in front of me. Like I said 2000 PSUs were not made as a series but each was custom made for a particular desk. It needs close inspection to find out. If you don´t know how to do it don´t try it. Get a good tech to do it for you. If done wrong it will blow your PSU or your desk.
If you use the original (850) PSU it will save you all that trouble. It has more than enough power to supply the desk even if it´s modified. Make sure it has a fan, otherwise it will run hot.
Anyway, have the PSU recapped and the thermal grease for regulators, power transistors and rectifiers renewed.
hope this helps
Jens
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Re: Matchless hum ground noises !help!

Postby AnalogStudio7 » Sat Dec 24, 2016 3:25 pm

Contact GRS for the manual & schematics. I got a new manual for our Magnum & full schematics for $39 with shipping included.

They also have the PSU connector cables and also have a conversion cable for what you are trying to do. It takes the 8 Pin Amphenol cable down to a 4 pin cable for use with the AMEK Tac Scorpion, Magnum & others.

GRS is at info@grssystems.com at www.grssystems.com Their phone is 951-767-0271. I think extension 21 is for parts sales.

They don't show all items on their web site, so email them if you don't see what you are looking for.

I have been getting all of my parts, manuals and service done with GRS for years. Highly recommend them.

Cheers! Greg
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