Nakamichi PA-7E/ 80V DC Voltage of main Supply

deq2496 · 11th January 2007, 11:39 AM

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

djk · 11th January 2007, 03:18 PM

80V sounds about right, maybe a bit high.

The 60V sounds like a misprint.

XEAGLEKEEPER · 11th January 2007, 05:11 PM

the transformer secondary voltage is probably around 60 VAC.

Zero Cool · 11th January 2007, 05:16 PM

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

djk · 11th January 2007, 11:01 PM

It's a 200W amp, 60V is not enough no load voltage.

Zero Cool · 11th January 2007, 11:14 PM

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

XEAGLEKEEPER · 11th January 2007, 11:22 PM

60 vac x 1.414 = 84.84 - rectifier voltage drop - winding resistance - capacitor esr,etc. = roughly 80 vdc.....

djk · 12th January 2007, 01:28 AM

My DH500s are all 93V, the Soundcraftsman ran on a regulated 67V.

Zero Cool · 12th January 2007, 01:45 AM

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.

granted were only talking 3v

djk · 12th January 2007, 02:50 PM

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.

11th January 2007, 11:39 AM	#1
deq2496 diyAudio Member Join Date: Jan 2007	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

11th January 2007, 03:18 PM	#2
djk diyAudio Member Join Date: Feb 2001 Location: USA	80V sounds about right, maybe a bit high. The 60V sounds like a misprint. __________________ Candidates for the Darwin Award should not read this author.

11th January 2007, 05:11 PM	#3
XEAGLEKEEPER diyAudio Member Join Date: Jan 2006 Location: central Iowa	the transformer secondary voltage is probably around 60 VAC. __________________ Ret. USAF... AKA- Avionic * Solder slinger for hire...*

11th January 2007, 11:01 PM	#5
djk diyAudio Member Join Date: Feb 2001 Location: USA	It's a 200W amp, 60V is not enough no load voltage. __________________ Candidates for the Darwin Award should not read this author.

11th January 2007, 11:22 PM	#7
XEAGLEKEEPER diyAudio Member Join Date: Jan 2006 Location: central Iowa	60 vac x 1.414 = 84.84 - rectifier voltage drop - winding resistance - capacitor esr,etc. = roughly 80 vdc..... __________________ Ret. USAF... AKA- Avionic * Solder slinger for hire...*


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11th January 2007, 05:16 PM	#4
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	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

11th January 2007, 11:14 PM	#6
Zero Cool Audio Junkie diyAudio Member Join Date: Sep 2004 Location: MN	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

12th January 2007, 01:28 AM	#8
djk diyAudio Member Join Date: Feb 2001 Location: USA	My DH500s are all 93V, the Soundcraftsman ran on a regulated 67V. __________________ Candidates for the Darwin Award should not read this author.

12th January 2007, 02:50 PM	#10
djk diyAudio Member Join Date: Feb 2001 Location: USA	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. __________________ Candidates for the Darwin Award should not read this author.

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