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-   -   My NXV-500 Amp Build (https://www.diyaudio.com/forums/holton-precision-audio/277867-nxv-500-amp-build.html)

bikenut 31st July 2015 12:15 AM

My NXV-500 Amp Build
 
10 Attachment(s)
Hello Folks:
After reviewing this thread and reviews on the Holton Amp site I decided to take the plunge and build a NXV-500 amp. It's a dual mono, single chassis amp. I didn't have the space for 2 mono amps in my audio stand. I'd like to thank all the guys who have posted their amps on this site. They really helped me make up my mind on this project, and gave me a lot of ideas on how to put all this together.

I've only ever built from scratch an Audio Note DAC kit, which involved soldering all the components on the boards, and that went well.
I have needed quite a bit of help online from Anthony at Holton Amps. Many thanks to him.

I'm almost finished, I shorted out something on one of the Volt One modules adjusting the voltage, and after trying to fix it with guidance from Holton Amps, I've returned it to Anthony for repair. So, I really haven't be able to listen to it, other than a very short test to see that it produced music, this was before I started to adjust the voltages, and bias settings. So, I'm excited to finally finish it and start enjoying the amp.

Here is the config of my amp:
2 x NXV500L modules
2 x NXVPSU-Two modules
2 x NXVolt One R2.1 modules
1 x Power One R3.0 AC mains controller

Chassis - ModuShop Chassis from Italy
Transformers - 2 x 800VA from SumR made locally near me around Toronto.

I wasn't prepared for all the drilling of holes in the metal chassis, especially without owning a drill press. Also, I should have ordered a larger chassis, fitting everything in a single chassis was a challenge, but after making a brace to raise the 500 amp boards, it all fit. Got that idea from someone else on this site.

Here are some pics of my almost finished amp. The quality of some photos is not great. The LED power button I like, it's blue when not on, turns red when manually turned on, and is a kind of pink when turned on via the 12v trigger. It was hard to get a nice photo of the LED lights. I also included the specs on the transformers I ordered, with guidance from Anthony at Holton.

Regards, Bill
Stouffville, Ontario, Canada

bikenut 21st September 2015 10:31 PM

BIAS Help
 
I could use some assistance on my 500 amp completion.

Would anyone who has done the bias of the 500 amp modules tell me where they put the positive and negative leads of their meter on the modules to make the voltage adjustments with the VR2 trim pot.

If you can tell me the exact location or component address on the boards, that would help me a lot.
I'm not sure how to complete this last task.

Thanks, Bill

zeepup 21st September 2015 11:20 PM

Quote:

Originally Posted by bikenut (https://www.diyaudio.com/forums/holton-precision-audio/277867-nxv-500-amp-build-post4459282.html#post4459282)
I could use some assistance on my 500 amp completion.

Would anyone who has done the bias of the 500 amp modules tell me where they put the positive and negative leads of their meter on the modules to make the voltage adjustments with the VR2 trim pot.

If you can tell me the exact location or component address on the boards, that would help me a lot.
I'm not sure how to complete this last task.

Thanks, Bill

Arn't they already setup from Anthony ?

bikenut 22nd September 2015 01:33 PM

The documents I was sent state that the ohms resistance and bias needs to be set.
When I did the ohms setting, it did need to be turned down from what it was, to 20 ohms or below.

You did not do this with yours?

zeepup 22nd September 2015 02:32 PM

Quote:

Originally Posted by bikenut (https://www.diyaudio.com/forums/holton-precision-audio/277867-nxv-500-amp-build-post4459917.html#post4459917)
The documents I was sent state that the ohms resistance and bias needs to be set.
When I did the ohms setting, it did need to be turned down from what it was, to 20 ohms or below.

You did not do this with yours?

I have the little nvx200's, didn't get any documentation with them.

Leikis 24th September 2015 07:07 PM

1 Attachment(s)
I measure over the 100K sms resistors on the end of the amp board. You should read mv
0.4-0.9 depends on how good your heatsinks is :-)

bikenut 26th September 2015 04:12 PM

Quote:

Originally Posted by Leikis (https://www.diyaudio.com/forums/holton-precision-audio/277867-nxv-500-amp-build-post4462755.html#post4462755)
I measure over the 100K sms resistors on the end of the amp board. You should read mv
0.4-0.9 depends on how good your heatsinks is :-)

Leikis, thanks for the photo, it really helps confirm the location of the resistor on the module. I'm not very experienced at this.

In the past, when trying to measure the resistor, my meter lead shorted across the mosfet pins and there was a spark.
So, I don't know if this is the cause of not being able to adjust the bias. Could one blown mosfet be the cause of the issue?
When I measure the resistor, I get no voltage reading.

The PSU on the channel keeps blowing the fuses at V1+ and/or V1-.

When trying to adjust for bias by turning the VR2 pot on the amp module, there is no change in voltage, it stays at zero volts.

I hooked up a speaker to the amp, and it's very distorted.

Any ideas what might be wrong, or what to check for?

Leikis 26th September 2015 04:15 PM

I suggest you speak to himself, the man !

zeepup 26th September 2015 04:15 PM

Quote:

Originally Posted by bikenut (https://www.diyaudio.com/forums/holton-precision-audio/277867-nxv-500-amp-build-post4464655.html#post4464655)
Leikis, thanks for the photo, it really helps confirm the location of the resistor on the module. I'm not very experienced at this.

In the past, when trying to measure the resistor, my meter lead shorted across the mosfet pins and there was a spark.
So, I don't know if this is the cause of not being able to adjust the bias. Could one blown mosfet be the cause of the issue?
When I measure the resistor, I get no voltage reading.

The PSU on the channel keeps blowing the fuses at V1+ and/or V1-.

When trying to adjust for bias by turning the VR2 pot on the amp module, there is no change in voltage, it stays at zero volts.

I hooked up a speaker to the amp, and it's very distorted.

Any ideas what might be wrong, or what to check for?

Grab your meter put it in beep mode to see if there are any shorts, Then put black into screw hole on the heatsink, then touch every transistor lead and see if any beep, NONE should if one does, then you have a short between the heatsink and transistor, maybe a metal shaving or something..


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