switched PS

golanko

New Member

Join Date: Nov 2008

Posts: 1
#1

switched PS

11-04-2008, 09:39 AM

hi,
i designed a power supply for RFID application at 125KHz using ST L5970AD according to the application sheet, and added LM7805 at the output to stabilize the voltage and to lower the ripple and noise. i still have a problem at 10% of the boards. i think the problem is with the noise level at the output. can u advice how to reduce the noise?
Tags: None

Previous template Next

Removing electrical noise introduced by fan

by tony359

Hi all,

I am working on a sound processor, it tends to overheat so I fitted a fan inside. The fan is connected to the +15V of the PSU via a DC-DC converter based on the LM2596 to reduce the voltage to around 10.5V.

Unfortunately the analogue circuitry is picking up the noise from the fan in two ways:
1. The fan is close to the analogue section, the motor itself gets into the outputs so I'll have to move it somewhere else
2. Even with the fan running outside of the case, there is still some noise which is clearly going back to the processor via power line....

2 Photos
- Channel: General Electronics Technical Discussion
11-28-2023, 05:18 AM
Onkyo TX-SR805 noise in one channel

by MegaZAC

Surprisingly enough, this receiver doesn't have the DSP chip issue. The HDMI board does not get hot, and sound over HDMI works fine.

Regardless of the input, the right channel has noise that is clearly noticeable even on average volume level. The only cases when there's no noise is when VCR input is selected (some tracks on the board are damaged, maybe that's why), or if HDMI input is selected but nothing plugged into it. In all other cases, even when no input is connected I still have the noise.

There's some logic behind it. As soon as I select an input I get only left...
- Channel: Troubleshooting Audio Equipment
04-23-2025, 10:09 PM
Philips HTS8000 home cinema noise problem

by courtcircuit

Hello

I have since a long time a Philips HTS8010S/01 which has been old but was doing the job.

Since a few days, it starts by making a weird "static" nois when switches on for a few seconds to a minute and then works like a charm.
Noise loudly outputs from the 3 channels, even if no signal is sent by the controler.DVD to the subwoofer/amp unit.

I was thinking of a soldering that was starting to be damaged and that was only doing the job after a few seconds of heating, most probbaly on the power board
Removed each of tyhe boards
...
- Channel: Troubleshooting Audio Equipment
02-08-2025, 08:22 AM
LG 50PB690 power supply terrible noise

by Biruslapio

I bought this TV with really bad oxidation on the power supply and bottom X boards, it was working but during pickup there was a lot of background noise so I don't know if it had this problem before.

As soon as I could I opened the tv and started working on it, did not test it before since it had back bars on the screen and obvious signs of humidity. The X boards were replaced and the screen now works 100%, but the power supply...

I washed the board and resoldered almost everything on the primary, the oxidation happened because of constant mains AC current flowing,...
- Channel: Troubleshooting TVs and Video Sources
07-13-2022, 12:46 PM
Samsung LE40F86BDX (model 2007) noise in picture

by tracid1987

Hi

I have this TV bought back in 2007 and used it for playing on PS3 for 4-5 years actively. After then it was barely used. It was mostly in stand-by mode or plugged out of mains completely for years. Today when i turned it on i have noticed noise in picture on two different locations of the screen. As you can see on the photos (see attachments) the noise is only in a small rectangle area, and if you look at it closely you see that one noise rectangle area is at the upper left corner of first half of screen, the other noise rectangle area is at the upper left corner of the second...
- Channel: Troubleshooting TVs and Video Sources
08-21-2021, 01:48 PM
Loading...
No more items.

switched PS

Related Topics