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Old 10-18-2017, 05:05 PM   #21
UserXP
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Default Re: Sony Wireless Headphones MDR-RF820

I got my caps today. I will take some pictures of the caps for you guys to see how they look like. They truly seem to be genuine Rubycons. I recapped the transmitter base PCB, but unfortunatelly, the problem is still present. Still occasional hiss sounds appear. But there is a slight difference now, they do not get worse when moving around the room. I guess these headphones started exerting some FCC directed behaviour, causing an undesired operation.

Anyway, I only ordered replacement caps for non-Rubycon caps, but maybe some of the Rubycons went bad. Maybe it's not the caps at all. I also recorded the hissing sound with a microphone, but I don't know if it is possible to attach a file type other than image.
I will post some images for you to see the recapping results, but I am getting tired of this malfunction. The recapping went smoothly, but the results were and still are disappointing. I have a bigger fish to fry now, and that is the ongoing PSU problem.

Last edited by UserXP; 10-18-2017 at 05:07 PM..
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Old 10-18-2017, 06:28 PM   #22
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Default Re: Sony Wireless Headphones MDR-RF820

Well, I suggested this several posts back, but I didn't get an answer from you...
Did you try swapping the power supplies/adapters that power these stations? What about the audio cables between the station and whatever it is getting its signal from?

There is also a BA3308F pre-amplifier IC on the transmitter board. You should verify that it works by inputing a signal into the base and seeing if you get anything on it's output pins (pins 1 and 7, that is).

There are other ICs, but I can't see their numbers. I doubt they would have failed, though, so let's leave those alone for now and focus on the items above.

Last edited by momaka; 10-18-2017 at 06:32 PM..
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Old 10-19-2017, 06:51 AM   #23
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Default Re: Sony Wireless Headphones MDR-RF820

Momaka, thanks for your your reply. I did test my base at my sister's, when I wrote about comparing the operation between mine and her headphones. It meant that I connected my base to her adaptor (I didn't bring my adaptor and/or cables because she also has the same model and everything was compatible). My headphones did not hiss when receiving from her base, but her headphones did hiss when receiving from my base - both bases were connected to her adaptor one at a time.
Also, I added that additional 16V220uF capacitor near the DC plug on my base's PCB, but I guess it didn't make too much of a difference. I will include these pictures as soon as I get home and grab some time to do it.

Last edited by UserXP; 10-19-2017 at 06:52 AM..
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Old 10-19-2017, 08:35 AM   #24
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Default Re: Sony Wireless Headphones MDR-RF820

" My headphones did not hiss when receiving from her base, but her headphones did hiss when receiving from my base - both bases were connected to her adaptor one at a time. "

EDIT: I Read to late that you already know the problem is coming from the base.

Last edited by Moreno83; 10-19-2017 at 08:37 AM..
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Old 10-19-2017, 05:47 PM   #25
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Default Re: Sony Wireless Headphones MDR-RF820

Quote:
Originally Posted by UserXP View Post
Momaka, thanks for your your reply. I did test my base at my sister's, when I wrote about comparing the operation between mine and her headphones. It meant that I connected my base to her adaptor (I didn't bring my adaptor and/or cables because she also has the same model and everything was compatible). My headphones did not hiss when receiving from her base, but her headphones did hiss when receiving from my base - both bases were connected to her adaptor one at a time.
Ah okay, good! That means you isolated the problem to not being the power adapter or audio cable too.

With that said, just to make sure the issue is not the other caps you didn't change... get a hair dryer or a heat gun and heat the entire transmitter base PCB well - no so hot to burn yourself, but close. Then see if that makes a difference. If it does and the transmitter works, then you either have bad caps or a bad solder joint somewhere.
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Old Yesterday, 05:04 AM   #26
UserXP
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Default Re: Sony Wireless Headphones MDR-RF820

Here are the replacement caps, the ones I got from egekecu.

I am going to try the hairdryer trick now as it will be an easy access now that the base is apart.
Attached Images
File Type: jpg 20171020_124901.jpg (804.1 KB, 4 views)
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File Type: jpg 20171020_124942.jpg (1.20 MB, 4 views)
File Type: jpg 20171020_125057.jpg (1.33 MB, 4 views)
File Type: jpg 20171020_125119.jpg (1.24 MB, 4 views)
File Type: jpg 20171020_125226.jpg (939.7 KB, 3 views)
File Type: jpg 20171020_125310.jpg (728.2 KB, 2 views)
File Type: jpg 20171020_125324.jpg (874.8 KB, 2 views)

Last edited by UserXP; Yesterday at 05:40 AM..
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Old Yesterday, 05:53 AM   #27
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Default Re: Sony Wireless Headphones MDR-RF820

Nope, heating with the hairdryer had no difference whatsoever...

Here I have attached the hiss sample that I have recorderd by putting a microphone directly against one of the earpads and turning the headphones on, since the hissing is heard identically on both left and right channel. These "spikes" of hiss occur intermitently, sometimes in pulses, sometimes in intervals, and their duration varies - but are quite annoying when listening to music.
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Old Yesterday, 05:58 AM   #28
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Default Re: Sony Wireless Headphones MDR-RF820

@Momaka

You suggested to check the input. I am not sure what you were referring to, but if you meant the sound input, then yes, there is one. The base turns itself off and stops transmistting automatically if there is no sound input for about 4 minutes. As soon as it senses the sound signal again, it turns itself back on and starts transmitting again. This is a product feature.
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Old Today, 02:25 AM   #29
UserXP
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Default Re: Sony Wireless Headphones MDR-RF820

Is the included "hiss record" of any help?

Last edited by UserXP; Today at 02:26 AM..
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Old Today, 12:54 PM   #30
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Default Re: Sony Wireless Headphones MDR-RF820

Well there is not much else on the board besides caps and some small ic's.

In this case i would mark the potmeter as it is right now and slightly change it while playing some sound like music.....
Maybe the frequency changed a little.
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Old Today, 08:47 PM   #31
momaka
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Default Re: Sony Wireless Headphones MDR-RF820

Quote:
Originally Posted by UserXP View Post
Here I have attached the hiss sample that I have recorderd by putting a microphone directly against one of the earpads and turning the headphones on, since the hissing is heard identically on both left and right channel. These "spikes" of hiss occur intermitently, sometimes in pulses, sometimes in intervals, and their duration varies - but are quite annoying when listening to music.
Interesting.

So the transmitter is sort-of working then? As in, you can listen to music and whatnot, but only that there is also a hissing noise on top?

The hissing sounds almost like some high-power computer/digital noise is getting through. If you are listening to music, let's say, does the audio go out when you hear the hiss or does it continue with the music?

Quote:
Originally Posted by UserXP View Post
You suggested to check the input. I am not sure what you were referring to, but if you meant the sound input, then yes, there is one.
No, I meant trace the audio input on the transmitter board and see if it goes to the BA3308F pre-amplifier IC. If it does, then also see if the audio you get out of the BA3308F IC is the same or noisy.

Quote:
Originally Posted by UserXP View Post
Is the included "hiss record" of any help?
Yes. I think we need to define the issue a little better. Try playing a short music sample through the headphones and record that. Also mention/upload the short music sample you used so we can compare.
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