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Old 11-17-2017, 07:59 PM   #1
AsRock
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Question NAD T753 revisit

Hello all, i got a NAD T753 some time ago and got it up and running though a lot of time and effort.

Well once i got it working i did a few changes and was thinking of improving them ( pictures be added at the end ). And was thinking of just swapping out all the capacitors on the main board, i have the service manual for the actual version which is pretty detailed and i have found specs for the caps to replace.

Reason i am planning to replace them with new is that before i made the changes most were put under a lot of heat which must of done them any good what so ever.

Anyways just trying to confirm that audio capacitors are not required or even should not be used even if the specs are about the same ?.

Pictures are hosted from another site and is ok with the owner of the site, hopefully it's a none issue.

Before the changes the diodes are cramped up against a heat sink and cap, i was seeing some horrid temps around this are and no wounder they were failing all the time, i all so got some high quility diodes which have not been added as i had to wait 3 months for them and got some others that can cope with 150c.













All so added a heatsink on the underside too


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Old 11-18-2017, 03:24 PM   #2
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Default Re: NAD T753 revisit

Well i will try to be clearer what i am trying to find out.

For example one of the capacitors in question is a Samxon KM series 35v 20% 105c, this cap is on the main\ power board for the unit. Which has a ripple current of 1808.

Was thinking of replacing it with this https://www.digikey.com/products/en?...ds=UKA1V332MHD

Would this be ok ?,
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Old 11-21-2017, 01:28 PM   #3
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Default Re: NAD T753 revisit

Samxon KM is just a general purpose cap, you don't need to replace it with anything very special.
Audio grade caps are mostly snake oil, they *might* have some use in the audio signal path.
But otherwise they make no difference what so ever.
If I want to be picky the Samxon KM is rated for 1.8A ripple current at 120Hz, whereas that one you linked is only rated for 1.6A at 120Hz.
In reality that will make no difference at all though
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Old 11-21-2017, 03:18 PM   #4
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Default Re: NAD T753 revisit

I also attached the images.....
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Old 11-21-2017, 04:04 PM   #5
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Default Re: NAD T753 revisit

Quote:
Originally Posted by Per Hansson View Post
Samxon KM is just a general purpose cap, you don't need to replace it with anything very special.
Audio grade caps are mostly snake oil, they *might* have some use in the audio signal path.
But otherwise they make no difference what so ever.
If I want to be picky the Samxon KM is rated for 1.8A ripple current at 120Hz, whereas that one you linked is only rated for 1.6A at 120Hz.
In reality that will make no difference at all though
Well that was the idea and just replace, i have actually ordered all the caps to be replaced close as possible to the originals as possible.

Personally i think the Samzon caps are really good with near rated uf and 0.02 Ohm esr readings. But when this unit was repaired i was seeing 75c temps which is why i flipped the transistors. which has improved the area temps of around 44c. But i do not know how long those caps have been under that heat so was just thinking better safe than sorry.

What failed originally was 2 diodes and 2 caps, and did manage to get rid of most of that crappy glue they used back then.

Thanks.



Quote:
Originally Posted by Topcat View Post
I also attached the images.....
Thanks, maybe i should of put them in a spoiler.
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Old 11-21-2017, 09:38 PM   #6
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Default Re: NAD T753 revisit

Quote:
Originally Posted by AsRock View Post
Thanks, maybe i should of put them in a spoiler.
It just guarantees that folks in the future that might read this thread won't see a bunch of broken image links.....
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Old 11-22-2017, 12:39 PM   #7
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Default Re: NAD T753 revisit

Quote:
Originally Posted by Topcat View Post
It just guarantees that folks in the future that might read this thread won't see a bunch of broken image links.....
It also gives the green padlock as the links now don't go to a non HTTPS website
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Old 11-22-2017, 03:06 PM   #8
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Default Re: NAD T753 revisit

Quote:
Originally Posted by Topcat View Post
It just guarantees that folks in the future that might read this thread won't see a bunch of broken image links.....
Cool, although the host i have never had lost pictures over many years now, but you never know right!.

Better be safe than sorry, as it's very annoying when your looking for some thing and the picture is either missing or hosted on data limited site.

should have my caps on Saturday.

Noticed another thread on a T753 on here it's a shame as i missed that as i actually had the parts he was after.

Last edited by AsRock; 11-22-2017 at 03:10 PM..
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Old 12-20-2017, 05:42 AM   #9
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Default Re: NAD T753 revisit

Yes, it’s my thread:

https://www.badcaps.net/forum/showthread.php?t=57238

My digital board is damaged by lightning and I have no plans of repairing it. I lost a lot of time with this bitch. It works in analog mode but it’s useless in many other ways.

Quote:
Originally Posted by AsRock View Post
i actually had the parts he was after.
What?

Last edited by Chungalin; 12-20-2017 at 05:43 AM..
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Old 12-20-2017, 02:34 PM   #10
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Default Re: NAD T753 revisit

Hi, i was just saying that their was a good chance of having the parts you needed, although not until later noticing you in Spain. Shipping though NAD is like $20 even for a diode which each Zdiode was around $3.30 a pop which i ended up getting mine of Digikey for about $0.40 a piece + $5 shipping which worked out much cheaper.

Well i did get around in replacing all but one cap, as i later found was coursing a buzz in the speakers so i ended up removing it.

Only reason i suspected this cap was due to design, not noticing when i ordered them one was a tall slim type and removing it and putting a old SAMXON cap back in which was much shorter than the Nichicon.

I all so replaced all the caps on the front channels too which one was way out of spec which were a mix of SAMXON, KSC and SS caps.

Both of my NAD T753's work flawlessly now.

And yes the units are a pain in the ass which is partly why i flipped the transistors to i could test more of the voltages, all so improve the cooling there to by adding copper shims for contact with the casing too which improved the temps inside by another 10c even after using it for hours. So that section runs around 35c which is half or more less than it used too.

I wish i had the know how to turn it in a simple power amplifier and get rid of all other crap and make my own amp out of the rest.


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Old 07-23-2018, 09:17 PM   #11
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Default Re: NAD T753 revisit

thanks for posting this thread! - about to recap my NAD 326BEE integrated amp in order to get rid of the crappy KSC caps and put first-tier Japanese in - Rubycon, Chemi-con, Nichicon, Panasonic, ELNA, and Toshin Kogyo are the only electrolytic cap brands I will let into my equipment!
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