Nakamichi PA-7E/ 80V DC Voltage of main Supply - diyAudio
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Old 11th January 2007, 11:39 AM   #1
deq2496 is offline deq2496  Switzerland
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Default Nakamichi PA-7E/ 80V DC Voltage of main Supply

I measured 80VDC on the main caps, the service manual says it shut be 60VDC

My unit is a 220V PA-7E version.

So a little bit higher then 60VDC I wood expect but 80VDC ?

Can someone thell me if the Voltage I measured is ok or much to high.

There is no option to set the Transformer for 240VAC.

Thanks
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Old 11th January 2007, 03:18 PM   #2
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80V sounds about right, maybe a bit high.

The 60V sounds like a misprint.
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Old 11th January 2007, 05:11 PM   #3
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the transformer secondary voltage is probably around 60 VAC.
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Old 11th January 2007, 05:16 PM   #4
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What are the PSU caps rated at? that should tell you if your voltage is close to being correct.

If they are rated at 75v then 60vdc should be about right. if they are rate at 100V then 80v would be about right from what i have seen in most major MFG amplifiers.

Zc
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Old 11th January 2007, 11:01 PM   #5
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It's a 200W amp, 60V is not enough no load voltage.
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Old 11th January 2007, 11:14 PM   #6
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yeah if i remember right it was 225w @ 8, i used to have a 7 long ago. 80V sounds about right. The Halfer DH-500 were 80v and my soundcraftsmens are 205@8 and those run 70V rails. My classe is 175w and it uses 63V rails so it really should be 80v rails for 225W
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Old 11th January 2007, 11:22 PM   #7
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60 vac x 1.414 = 84.84 - rectifier voltage drop - winding resistance - capacitor esr,etc. = roughly 80 vdc.....
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Old 12th January 2007, 01:28 AM   #8
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My DH500s are all 93V, the Soundcraftsman ran on a regulated 67V.
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Old 12th January 2007, 01:45 AM   #9
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Quote:
Originally posted by djk
My DH500s are all 93V, the Soundcraftsman ran on a regulated 67V.

boy it has been so long since i have had my hands in a 500 i just dont remember, you may be right, i remmeber it was high.

But i have rebuilt at least a dozen Soundcraftsmen PCR-800, 840, 860, Pro-power, 450x2, and DJ-900 amps and they all ran +/-70

The scmatics i have show 70 as well.

Click the image to open in full size.

granted were only talking 3v
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Old 12th January 2007, 02:50 PM   #10
djk is offline djk
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Thanks for the schematic. Although I have repaired several of these, I have never had a schematic of one.

You're right of course, a couple of volts won't make that much of a difference. I just wanted to make the point that the regulation allows them to start out with a lower voltage than normal and still produce full power out.
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