Help with Interference issue [resolved]

[networkn]

Hi I have my crack amp resurrected after a LONG break away, and keen to resolve a problem which I couldn't really find the root cause of last time.

Essentially the issue is that my voltages and everything check out, the sound is coming through loud and clear, and seems the amplification is working ok, but there is a weird interference issue not quite like static, which I am not sure the source of.

It changes ears depending on how far in or out of the jack it is, and almost sounds like high frequency (as in how fast it occurs not sound frequency) clicking with a high pitched sound coming through as well. I can detect it with anything plugged into the headphone jack and source doesn't appear to be the problem.

Is it quite likely the headphone jack?

The sound is recorded (barely) on my phone and is available to hear here, sort of. It's much much clearer than this on my ear!

https://www.dropbox.com/s/a5hdblk1pmsm1zx/Voice%20001.m4a

 

[fullheadofnothing]

Turn off your cellphone and wifi router.

 

[networkn]

Turn off your cellphone and wifi router.

Didn't help. What's next? When I wrote interference, perhaps I use the wrong term.

What component of the Amp could even be running at the same frequency of the cellphone or wifi ?

 

[networkn]

Volume doesn't have any affect on the sound issues I am experiencing.

 

[Paul Birkeland]

Is it quite likely the headphone jack?

No, it most certainly isn't the headphone jack.

This could be a funky solder joint on one of the UF-4007 diodes, or elsewhere in the power supply.  With your headphones plugged in, do you get this noise in both channels or just on one side?

Also, if you used plumbers' solder or plumbers' flux, this could be a potential result.

-PB

 

[networkn]

Hi There!

I am 99% sure I didn't use plumbers anything, I bought good quality something or rather from one of the reputable speciality electronics store. The Sound moves from the left ear to the right depending how far the headphone is inserted into the jack, but I don't think I can get it to happen to both sides at the same time.

Wouldn't poor solder or joint cause voltage or resistance issues?

 

[PassionForSound]

The reason it changes sides when you move the headphone jack in/out is because the contacts in the socket are touching different contacts in the plug. If you leave jack plugged in fully, which side is the noise on?

Sounds like it might be worth reflowing your solder joints based on PB's assessment of the issue.

 

[networkn]

Hi There!

On the right hand side. I'll take a look at the soldering in the next couple of days, hopefully it is an obvious problem.

 

[PassionForSound]

Cool. Good luck!

Question for the experts: can an issue that only exhibits in one channel be caused by the power supply? I would have thought that this would exhibit through both channels.

 

[JamieMcC]

I believe when the headphone jack is not fully inserted what you are listening to is a mono signal and think that's why the noise you are hearing travels from the right side to both side when moving the headphone jack in and out.

Which may be helpful in isolating the problem to the right channel.

 

[networkn]

https://www.dropbox.com/sc/cxhhfm1xkai1y38/AADzvJW4NPezpzZSO691ixeHa

Just checking these are the connections you want me to reflow? When you say reflow, do you mean add more solder to, or just reheat until the solder is liquid?

Not sure if you can see from the pictures if anything is amiss already.

Do I check all voltages and resistances again after?

 

[PassionForSound]

Reflowing is just a matter of heating the joint until the solder turns to liquid again and adding solder only if you think it's needed.

As an example of what you are trying to fix in these cases, one of the resistors in my Mainline attenuator looked like it was soldered, but on really close inspection I found a "void" around one of the resistor leads at the joint. Reheating the joint allowed the flux and solder to reflow and this time to make full contact with both leads in the joint.

It's possible to have a "void" in the joint that you can't see so reflowing (making sure all the solder in the joint liquifies and flows) helps to remove any of these that might exist.

 

[Doc B]

If you have any other tubes to try, plug them in and see if the sound changes at all. If not, it's probably a bad joint.

 

[networkn]

Hi There!

Unfortunately I don't have any spare, nor would I know where to start looking to find replacements in NZ. I was considering bringing some in from overseas, but I was waiting to get the Crack and Speedball installed first. I get my soldering iron back tomorrow hopefully.

This is the solder I have used. Hopefully it's ok.

http://www.jaycar.co.nz/productView.asp?ID=NS3013&keywords=solder&form=KEYWORD

 

[Paul Birkeland]

Yeah, that solder looks good. 

 

[networkn]

Reflowing is just a matter of heating the joint until the solder turns to liquid again and adding solder only if you think it's needed.

As an example of what you are trying to fix in these cases, one of the resistors in my Mainline attenuator looked like it was soldered, but on really close inspection I found a "void" around one of the resistor leads at the joint. Reheating the joint allowed the flux and solder to reflow and this time to make full contact with both leads in the joint.

It's possible to have a "void" in the joint that you can't see so reflowing (making sure all the solder in the joint liquifies and flows) helps to remove any of these that might exist.

Thanks for the explanation. I figured it was that, but I thought I'd check to be sure.

 

[networkn]

Could someone please confirm for me that it's ok for those components to touch each other? I presume so since the Amp actually works and voltages and resistances are correct.

 

[Paul Birkeland]

Which components?

 

[networkn]

Which components?

Hi There!

I think they are diodes, the black ones in the pictures I posted. There is no metal pins touching other pins, but the diode parts are touching each other a little.

 

[Paul Birkeland]

The black bodies of the diodes can touch, that's OK.  You just don't want the metal leads on a pair of diodes touching when they go to different terminals.