HPX250: Intermittent Noise Problem

L

Larry E McPherson

Member
In a year of regular field use of my 250 for wildlife videos, Barry's "HPX Book," and this forum I have gained considerable respect for the camera.

For the last 3 months I have been having an intermittent noise problem that I have not been able to isolate the cause of it. In the process I have gained familiarity with just about every leaf, wind, touch, or movement of the camera will cause as well as the fine points of mounting the mic in the Rycote system to eliminate absolutely every possible vibration or cable rub.

I am using a Sennheiser MKH 8060
mounted on top of the camera inside a Rycote WS-3 full windshield and windjammer (I have replaced the cable connecting the mic to the camera with no change in results.)

I connect the mic to the camera using Input 2, set the Channel switches so that the 1 mono input signal from the mic is sent to both audio Channels of the camera, and they end up sounding and looking identical—they both either have the noise or not in an identical way.

I have sent an MP3 file of the typical noise problem to Sennheiser USA and they are going to see if it looks like any of their known issues, but haven't heard back yet.

How about the camera itself—how do I determine if the noise is being created by camera and what can I do about it?

I can email an MP3 file sample of the noise to anyone kind enough to listen to it. Is there a way I can post the MP3 with the forum post?

Suggestions, please! Thanks!
 
8060 is a very good mike, so it's unlikely the cause of the problem... It could be the phantom power of the camera - I once had noise issues when I used an external power supply (Deneke) on another camera with my Sennheiser.. There was a loose solder connection (it's an old power supply). If you have access to an external power supply, try turning phantom power off in the camera and see what happens. If not, try inputting to CH1 and use that power. In the meantime, hopefully Mike (above) can identify what's going on...
 
For anyone who's interested, here is the file Larry emailed me:

http://mike-warren.net/vid/lm1050_Channel_1_Audio_Extracted.mp3

Now, for my take on what's happening.

It's not a acoustic problem. In other words, it's not caused by vibrations being picked up by the mic capsule. This sound is caused by a poor connection in a path that carries a DC component in addition to the audio. Unfortunately, that could be in a lot of places with your setup. All the electronics inside the microphone and the camera audio section have a DC component.

Common cause of noises like this can be dry solder joints and corrosion on components. Also, poor connections (usually corrosion) on internal plugs and sockets. The only external possibility I can see here is the cable, but you say you've already tried a new one.

Since you obviously use this system outside a lot, corrosion somewhere would be high on my list. Does the problem seem worse when the humidity is higher? What about temperature? Does it seem worse in particularly hot or cold conditions?

Intermittent faults are the bane of my life. Tracking down the cause can be extremely time consuming.

Firstly, can you hear the noise if you monitor the signal live? If not, that will place the fault in the circuitry after the monitor tap inside the camera. If you can hear it live (and I suspect you will) it could be inside the microphone, the socket on the mic, the cable (eliminated), the socket on the camera or the mic preamp in the camera.

Ideally, the cause of action would be to replace the microphone and see if the fault disappears. That will tell you which device is faulty.

Sorry for the disjointed reply. I'm pushed for time at the moment.
 
Larry E McPherson said:
In a year of regular field use of my 250 for wildlife videos, Barry's "HPX Book," and this forum I have gained considerable respect for the camera.

For the last 3 months I have been having an intermittent noise problem that I have not been able to isolate the cause of it. In the process I have gained familiarity with just about every leaf, wind, touch, or movement of the camera will cause as well as the fine points of mounting the mic in the Rycote system to eliminate absolutely every possible vibration or cable rub.

I am using a Sennheiser MKH 8060
mounted on top of the camera inside a Rycote WS-3 full windshield and windjammer (I have replaced the cable connecting the mic to the camera with no change in results.)

I connect the mic to the camera using Input 2, set the Channel switches so that the 1 mono input signal from the mic is sent to both audio Channels of the camera, and they end up sounding and looking identical—they both either have the noise or not in an identical way.

I have sent an MP3 file of the typical noise problem to Sennheiser USA and they are going to see if it looks like any of their known issues, but haven't heard back yet.

How about the camera itself—how do I determine if the noise is being created by camera and what can I do about it?

I can email an MP3 file sample of the noise to anyone kind enough to listen to it. Is there a way I can post the MP3 with the forum post?

Suggestions, please! Thanks!
Click to expand...

I had an audio noise problem where I got some hiss one time. I sent the camera into Panasonic and they couldn't duplicate the problem but they replaced the main power board.

"They replaced the main power board since it has been recently redesigned. They told me the new power board affords more protection to transients rejection of noise & interference from the outside world as well as containing more of its own noise a little better as well. They also told me to power off the camera before changing batteries - which I always do."

If you have some down time you may want to send it in for a checkup. I hope this helps you.
 
All of the replies are helpful and insightful:

Mike Warren, I agree with your take on what's happening:
1) It is not caused by vibrations being picked up by the mic capsule.

2) This sound is caused by a poor connection in a path that carries a DC component in addition to the audio.

The problem does seem to be becoming more frequent and irksome; the weather has been getting cooler and dryer, but no hard information on that.

I can hear the noise if I monitor live with the headphones, which I have done numerous times to try to isolate the problem. I have learned from that that it can happen when I am moving the camera or it can happen when the camera is perfectly still and/or no wind or ambient sounds. The noise can occur or not both when it is recording or in standby.

As per Mac's suggestion I am going to shoot a session this morning using input for CH1 and monitor live as much as possible.

Then this afternoon I am going to mount a MKH 8020 on the camera. The 8020 is an omni and not really useful for my application, but good for the test to see if it is the 8060 causing the problem.

I am really at this point suspecting something faulty with the camera.

So rejdmast, is there any special person to talk to at Panasonic to get the electonics checked or new power board?

Thanks!
 
My latest tests today confirm:

1) It makes no difference whether I connect a mic to the camera via Input 1 or 2—either way I get noise.

2) I connected a completely different microphone and XLR cable and got the same noise.

I now believe whatever the problem is is located internally in the HPX-250 camera. My 250 was probably one of the early cameras of that model produced, Serial # I1TCA0240, and purchased October 11, 2011.

Monday I need to contact Panasonic and send it in for repair.

Does anyone have suggestions for who to contact at Panasonic?
 
Did you have phantom power switched on?

Oh, and did you try it without the signal being fed to both channels, and is the noise on both or only one channel?
 
Yes Mike!

I always have had phantom power switched on. That is the only way I ever set it, the 8060 requires phantom.

I did try it without the signal being fed to both channels, when you connect via Input 1 the only option is to feed it to Channel 1, and when I do that I get noise on Channel 1.

When I connect to Input 2 then I set the switches so the microphone signal is sent to both Channel 1 and Channel 2—that is my standard and preferred way to set it—and when I do that I get identical audio and identical noise on both channels.

Thanks!
 
A good test would be to see if it also fails when fed just to input 2. If you still get the noise, then I'd put the fault in the phantom power supply. Either way, by taking the mic and cable out of the equation you've proven the fault's in the camera. But it will help Panasonic find and fix it quicker if you can supply more information. Invariably, intermittent faults go away whenever a technician tests it, and unless it's a known fault they may conclude that the fault lies elsewhere unless you have enough data to prove it's in the camera.
 
To me it sounds like either a broken capacitor or a cold solder joint. certainly needs fixing. I would send it to panny...we have 5 years, one of the reasons I bought it!
 
OK Mike!

I just tested the camera with the mic connected to Input 2 and the camera's external side switches set so that the signal went only to Channel 2 -- when I did that I get noise on Channel 2 and nothing is recorded on Channel 1.

So according to your thinking the fault is in the Phantom Power supply and I should tell Panasonic that is what I suspect is the problem as well as the various tests and results leading to that conclusion.

Many thanks Mike!
 
Probably best not to presume to tell them their job, but listing your test results and stressing that the fault is intermittent should go a long way to helping them fix it quickly.
 
Thanks rejdmast!

I emailed Aki Suzuki and now my 250 is in route to Panasonic NJ Repair Center. Hopefully I will get it back soon and my noise problem will be history.

Thank you everyone for your input!
 
Update Intermittent Noise Problem:

December 3, 2012 - I sent my HPX250 to NJ warranty repair.

December 19, 2012 – I received the unit back, but it still had the Intermittent Noise problem—there was no performance change. They said they had replaced the XLR input connectors and circuits on the top handle/internal microphone unit.

December 20, 2012 – After a day of extensive testing, much phone dialogue, emailing them sample MP3s of the problem I shipped the unit back to NJ warranty repair, and they put more advanced personnel on the case.

January 25, 2013 – After calling them many times I received a loaner HPX250 to use while they continued to figure out the problem. The loaner would freeze up after being on for about 5-minutes and the only way to turn it off was to remove the camera. It then would not turn on until about a 5-minute wait. That camera turned out to be unusable. After another week they sent me a brand new HPX250 that they had tested extensively before sending.

February 1, 2013 – I received the new HPX250 and began testing and using.

February 6, 2013 – After 7 hours of total use over a period of 5 days the Intermittent Noise problem occurred with the new camera. The noise occurred on the 4th clip out of 10 shot, it did not occur on the clips before or after that. I have called the Panasonic NJ repair people. They were not surprised the noise occurred with the new camera, they know there is a problem in the HPX250 audio system. They do not yet know what the problem is, but they say they are going to get to the bottom of it.

I still do not have a reliable camera! If anyone has any insights or suggestions at this point, please share! Has anyone else even had a similar problem with the HPX250?
 
None that I have noticed, will have to test some to see. I have to send my camera in for lens focus issues at it wont hold steady when zoomed in, but nothing so far with sound.
 
The above posts gives me enough reason to postpone and not to rush on getting the 250 until I hear no issues, I just don't like to ship a brand new camera for repair.
 
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