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MA5002VZ Fan Speed


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#1 lambroffs

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Posted 29 March 2004 - 02:18 PM

We are currently testing our first amp rack since switching to PIP-USP3 modules (from PIP-USP2).  In the rack that I am now testing, we have three MA5002's and all are running very hot (~45% thermal capacity) when sitting at idle.  The amp at the bottom of the stack is running coolest and the amp at the top is running hottest.  The problem appears to  be the internal fans not running fast enough.  We only measure approx 60VAC across each internal 115VAC-rated fan.  Amp thermal levels (as shown on IQ software) heat up dramatically when test tones are applied (using only a minimal 250W load).  I am frequently getting the "TDH above limit on channel xx" message in IQ software which I'm assuming is a temperature alarm message, but can find not referene to TDH in the manual or help menu.

Back when we used PIP-USP2 installed in MA5002VZ's the internal fans were heard loud and clear whenever power was applied to the amp.  Under the PIP-USP3, the fans are either running quieter or slower to the point where you cannot hear them pushing air (although opening the top cover shows that they are turning... although much slower than expected.)

Is the fan speed controlled on or off the PIP module?  I have upgraded all PIPs to V1.10 firmware.

Any insight is appreciated.

Scott

#2 Bradford Benn

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Posted 29 March 2004 - 03:05 PM

The fan speeds are controlled by the amplifier itself and not the PIP cards.

I will talk with other people at Crown and see what ideas they have.
-=Brad

Bradford Benn
Business Development Manager - Crown International
http://www.crownaudio.com/

#3 KWhitehead

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Posted 29 March 2004 - 04:10 PM

Scott,

As far as how the MA5002VZ fans work they are proportional with heat. So depending on how warm they are is how fast the fans will run and for how long. You will measure different AC voltages across that fan at any given time. The 45% thermal is via IQ but it doesn't mean that the amplifiers are truly running that hot. At idle do you feel heat blowing out of the back of the amplifiers? If you do it could be one of two things as far as the amplifier goes. 1) the output bias voltage could be out of adjustment running high and causing cuurent flow in the output which will cause heat. 2) the ODEP voltages are out calibration. Since the thermal indication via IQ is based off of ODEP voltage this could be why you are seeing higher thermal %'s but yet the amplifier may not be running that hot. Brad Benn was going to ask IQ engineering if there was any MA5002VZ / USP3 firmware issues just to double check. We have not heard any and their's many out there using this combination and working fine. It's possible the amplifiers just need to be re-calibrate.

Thanks,

Kip Whitehead
Technical Support