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Repairing and tests Electrovoice P2000

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DjLeco View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DjLeco Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2014 at 8:47pm

Kedward, all Dynacord and Ev series used in most part same schematics on amplifiers.

 
 
Ev P2000 are Dyna L1600, and PV3000 are Dyna L2400.
 
 
10mV on that connector service if measured, corresponds to almost 120mA bias per side, that means around 240mA per channel wich is too much more for one AB class amplifier, it will run hot even on idle state, (it will dissipate almost 25 watts in idle per channel) and most of them, after years of using , because thermal stress hot-cold, and weakening mechanical contact of superdiode transistor 2SC4793, (I was able to unscrew it just with my nails from 2 fingers) loses thermal biasing auto correction, getting slightly into thermal avalanche uncontrolled by superdiode transistor.
 
Those are most ways for amp to fail.
 
Maybe that's why geoSal loses 8 amps like that.
 
 
50mA per side or 100mA per channel is more than enough, trust me.
 
On preliminary tests, on 1W/8 ohms load, (2,83Vrms) for 20Khz sinusoidal to be perfect on output (avoid crossover distortion) , I needed just 14mA, respectively17mA for low and high side of final stage, because good matching of output devices and predrivers too.
 
Maybe Ev and Dyna, uses more bias to compensate unmatched output devices used?
 
Could be one possibile way...
 
But in that case, the trannie with bigger Hfe, will share most peaking current, failing first from the 4 parralel used...
 
Also one major problem of this design, is BAD in VAS stage, where current there are around 100+mA shared by 3 parraleled MJE 340-350 wich running very very hot, and are not placed on air zone of fans...
 
Maybe that's why geoSal loses 8 amps like that?
 
I say it again.
 
 
For a good performing of an amplifier, especially with deep darlington triplet on output, the VAS stage current is enough of 10-15mA to drive correct entire triplet.
 
On mine amps design I use less than 20mA VAS current, and the amp is able to deliver and sustain more than 31A rms on output, even on 1 ohm load.
 
Watch here from min 2:50 until 3:47 where I load the amp (loaded with official 2 ohms deja), with another 2 ohms parralel, to be equivalent of 1 ohm dummy load.
 
 
I'm not trying to blame or discard Ev design, I'm not better than their designers, but this design can be much improved because is not a bad one, just implementation of it, suffers...


Edited by DjLeco - 23 June 2014 at 11:39pm
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kedwardsleisure View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2014 at 11:18pm
Quote it will dissipate almost 25 watts in idle per channel




140-200W is stated as correct by EV.

I think I will continue to exercise humility.




Kevin

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DjLeco View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DjLeco Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2014 at 11:41pm
That's total power consumption  for both ch, I think.
 
Not studying so much manual service and stuff because poor quality of xeroxed copy...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2014 at 8:58pm
do you want me to send you mine
Kevin

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DjLeco View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DjLeco Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2014 at 9:07pm
Yes sure.
 
claudiu971around yahoo dot com
 
Thank's!
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Tan-2 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tan-2 Quote  Post ReplyReply Direct Link To This Post Posted: 13 July 2014 at 3:08pm
would agree with ken there..done a few of these amp's and followed the notes..the only test I did not carry was to short the amp at full power.. this being on the ev p3000.Smile
Logic will get you from A to B. Imagination will take you everywhere.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 22 July 2014 at 7:25pm
*bump

Leco, where did they place those NTC resistors like R163, R164? Are they mounted in the hole filled with thermal grease like shown on your picture?


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DjLeco View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote DjLeco Quote  Post ReplyReply Direct Link To This Post Posted: 22 July 2014 at 10:02pm
Yes, there they are.
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M4trix View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 22 July 2014 at 10:55pm
Thanks. Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bamfwrx Quote  Post ReplyReply Direct Link To This Post Posted: 07 August 2014 at 11:19pm
Mr Edwards is the service manual offer open to anyone.  I can't see to find a copy in the US
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Post Options Post Options   Thanks (0) Thanks(0)   Quote verano Quote  Post ReplyReply Direct Link To This Post Posted: 18 March 2018 at 9:36pm
Sorry for replying to an old topic...

I have a P3000rl with blown output board


For the resistors, what kind of wattage do you need ? 1/8 watt ?



Resistors same value: 
 
R24,R23,R22,R21,R31,R157,R158,R159=2,2 ohms flame proof
 
R11,R10,R9,R8,R109,R108,R107,R106=47 ohms flame proof
 
R27,R26,R98,R96,R112,R111=10 ohms flame proof
 
R188,R197=56 ohms flame proof
 
R113,R97,R95=68 ohms flame proof
 
R115,R94=22 ohms flame proof
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tan-2 Quote  Post ReplyReply Direct Link To This Post Posted: 20 March 2018 at 2:11pm
Hello..these amps take a little getting your head round to repair them. The heatsinks carry full supply voltage so watch out there.

Also the offset at the speaker connection should be 10mv per side.
Logic will get you from A to B. Imagination will take you everywhere.
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