Dell Genesis 1702FP Whining Sounds

[ttcole1254]

I have a Dell 1702FP from 2001 to 2002. I got it from a friend, and they never really used it throughout the years, so it still runs perfectly well and has a great picture. Except this annoying whining noise. It seems to change based on how many black or white pixels there are. If the screen is mostly white, then the noise is very annoying and high frequency. If the screen is mostly black, then the noise almost goes away entirely. Opening up the monitor, the whine is coming directly from the processing chip that says "Dell Genesis" on it.

What's worse, is now that feedback started coming through my computer speakers. Same exact whine, but amplified. That's fun to listen to :P. What's strange though, is that the monitor behaves and looks normal. It just doesn't sound normal. It runs on a power brick btw, and does not have power circuitry on the back. Does anyone know what this could be?

I have a new acer sitting right next to it, and it doesn't have any problems at all.

Thanks,
Tyler

[999999999]

Re: Dell Genesis 1702FP Whining Sounds

How do you know it comes directly from the Dell Genesis chip? What I would guess is that applying pressure to the chip flexes the PCB just enough that it stops a noisy inductor from making the noise. If not, then I'd suspect the PSU is bad, though it might be either way.

[ttcole1254]

Re: Dell Genesis 1702FP Whining Sounds

I listened to the board and it seemed to be the chip. I don't remember if there is an inductor near it or not.. Flexing the board does actually have an effect on it.

[ttcole1254]

Re: Dell Genesis 1702FP Whining Sounds

Happy holidays everyone!

Okay so I have some good news and bad news.. It seems like the PSU is okay. I tested it with a multimeter and it's reading as 13 volts (it's labeled for 14) and the amps aren't measuring, maybe I'm doing it wrong. I tried removing the board while it's powered on to try and isolate the noise, and it still seems like it's coming from the main processing chip. Unplugging the backlight inverter board doesn't change anything, but unplugging the panel and leaving the backlight does make it stop. The noise actually sounds like thousands of tiny electrical arcs, if that makes any sense. Monitor is still running perfectly other than the annoying noise.


Also, all the caps look okay but I haven't tested them yet. They're all relatively small as the power is already conditioned for the most part.

EDIT: I tested the two Sanyo caps on the board (16 volt 100 microFarad) and they read at 113 mF, so that would be make them good. There are some others, but they all look okay. Should I test every single cap?

[selldoor]

Re: Dell Genesis 1702FP Whining Sounds

Perhaps if you posted pictures of the board we could make better suggestions.
We can help a lot more if you please post good clear pictures of the whole chassis, and then pictures of each board, front and back (in the same orientation) and close up of connectors, (max resolution 2000x2000 and 2MB) using the manage attachments button, which is found by clicking "go advanced" under quick reply.

Please do not post inline and offsite as they slow down the loading of pages.

Examples of what is needed

https://www.badcaps.net/forum/attach...7&d=1280167246

https://www.badcaps.net/forum/attach...6&d=1280167246

https://www.badcaps.net/forum/attach...4&d=1280167246

[999999999]

Re: Dell Genesis 1702FP Whining Sounds

Without going into a tutorial on how to measure current with a multimeter, you have to break the circuit to do so. While a reading of 13V shows there are some signs of life, if it is labeled as 14V it should be at 14V or a little higher when not powering the monitor, not down at 13V. Was this voltage measured while it was powering the monitor or not?

While a multimeter can confirm a PSU is dead or damaged, it can't really be used to prove a PSU works properly as it won't show the ripple... ripple that could be excessive from something like bad capacitors for example.

However given that it is an external PSU and the portion in the monitor making the noise is bound to be further regulated down to a lower voltage, and given that the PSU isn't shutting off itself, I would still suspect an inductor in the regulation circuit, in the monitor itself, EXCEPT that I mean while that may be making noise, it may still be caused by the PSU not working properly. I suppose it could really be arching but there was no mention of any irregularities on the PCB like darkened areas, scorch marks, broken solder joints, etc.

I'm only playing odds though, I can't say it is impossible for a power surge or chip defect to be causing arching in an IC (chip) but it would be unusual for that to persist rather than immediately fry the path of the surge.

[ttcole1254]

Re: Dell Genesis 1702FP Whining Sounds

I will post pictures soon. I honestly didn't think of that. The first test was with the multimeter leads stuck into the socket, so it was not powering anything. With the monitor running, the voltage stayed at 13. The supply and monitor are over ten years old, so I'm not very trusting in them. Honestly, I probably should be looking at a new monitor, but it looks so crisp and clear and accepts DVI as well as VGA. I'd like to keep it going as long as I can if at all possible.

Looking at the main board, there are no visible scorch marks or any sign of a problem at all. Completely clean. If I couldn't hear the noise, it's otherwise working perfectly.

Also, I should add that the noise is constant on both VGA and DVI modes, and even happens with no cable connected, albeit greatly reduced (there's a Dell color test box that moves about the screen when there's no cable connected while powered on.)

[ttcole1254]

Re: Dell Genesis 1702FP Whining Sounds

I honestly forgot about the monitor.. it recently started flickering when a lot of white is being displayed, so I took it apart, flowed some flux under the GPU, preheated the board with a heat gun and heated the GPU to about 250 degrees to reflow it. Put it back together, and it no longer flickers, but is still making the whining noises as before.. I was hoping doing that would fix it XD

[lexwalker]

Re: Dell Genesis 1702FP Whining Sounds

I honestly forgot about the monitor.. it recently started flickering when a lot of white is being displayed, so I took it apart, flowed some flux under the GPU, preheated the board with a heat gun and heated the GPU to about 250 degrees to reflow it. Put it back together, and it no longer flickers, but is still making the whining noises as before.. I was hoping doing that would fix it XD

Possible source of whining noise...

- transformers (on the power supply board)
- SMD ceramic capacitors (look up "microphonic capacitor")
- leaking/venting capacitors (which should sound more like whistling or hissing)
- inductors and chokes (rare but if the coil/winding is loose then whine occurs)

[ben7]

Re: Dell Genesis 1702FP Whining Sounds

I'd say that it is a bad capacitor. Are there any inductors near the chip?

Try taking a straw, and put it up to your ear. Then, probe around to try and find the source of the whining.

What brand is the power adapter? My bet is that it is cheap or faulty.