X-DAC low frequency hum

[rumbustificator]

Hello people.  First post here.


I've been running a MF based system (which I love) for a few years now; an XA200, pair of XA50 monoblocks, an X10D and an X-DAC.  

Recently, the XDAC (the HDCD version) has developed a low-pitched hum which has made it unlistenable. I've tried swapping the wallwart with the X10D to see if that was the problem, but had the same issue.


I'd much rather be saving my pennies for an X10D upgrade kit and new tubes, than having to replace the DAC - so, has anyone had this problem before or have any ideas for a practical repair job?

My skills are at a level where I'm not an actual danger to myself or others with a soldering iron - but not much beyond that

[PinkFloyd]

Hi Rumbus,

Welcome to the forum If the DAC has been in the same position (in your system) for a while then it's unlikely to be a ground loop. Did the hum come on gradually..... ie: started off pretty low level but is now very noticeable or did it come on suddenly one day?

The X-DAC is exactly 20 years old (introduced in 1997) so it's more than likely that a few of the capacitors have dried out / gone high ESR. Some of the 85C general purpose Jamicon capacitors tend to go after about 15 years in an X-CAN V2 but the ambient temperature inside a V2 is a LOT warmer than inside an X-DAC but at 20 years I would definitely be looking at re-capping the X-DAC. If you have left it powered up permanently (as MF recommend) then it will definitely be one or more of the capacitors.

Are you positive it's the X-DAC that is humming and not something else it's connected to?

A recap using good quality 105C rated Panasonic caps is not expensive....... probably around the £50 mark (parts and labour) but if you do it yourself a LOT cheaper.

Best regards,

Mike.

[rumbustificator]

Thanks Mike.

I have kept the whole setup running 24/7 (for a good few years now) so I shouldn't be surprised that it's starting to show some signs of wear!

Could you let me know what I'd need to recap it, please? Hopefully, if that goes well, I can do the X10D next.

[PinkFloyd]

May 7, 2017 16:54:45 GMT rumbustificator said:

Thanks Mike.

I have kept the whole setup running 24/7 (for a good few years now) so I shouldn't be surprised that it's starting to show some signs of wear!

Could you let me know what I'd need to recap it, please? Hopefully, if that goes well, I can do the X10D next.

That's over to you Rumbust,

Pop the hood, take a few photos and let me know the values of the existing caps...... the X-DAC is not something that has come into my hands but it will be the usual 1000uF / 35V Jamicon power caps on board and the values are clearly marked on the sides of the capacitors so pop the hood and let's have a look....... it will be simple to replace them but let's add a bit of extra capacitance in the PSU section / replace the stock 1000uF with 1500uF..... that will improve things in the sonic dept. too.

awaiting photos

best regards,

Mike.

[rumbustificator]

Hi Mike,



No obvious sign of bulging or damage, but something's not right somewhere so...


I count 6 capacitors. All Jamicon and (I think) one 1000uf 16V, two 470uf 25V, two 100uf 50V and at the top attached to optical input a 47uf 63V (which is less likely to be the issue as I don't use the optical input).

Just trying to work out how to embed photos - do they need to uploaded to somewhere first to generate a URL?

[PinkFloyd]

Hi Rumbus.............

(what's your real name BTW? Rumbus sounds like a bunch of pissheads drinking copious amounts of rum on a dedicated rum bus outing)

Create a free photobucket account: photobucket.com/signup/

Upload photos and then copy and paste the "IMG" link into your post here....... as simple as that.

Mike.