Sparkle 250W noise....

**Gianni** · 08-07-2009, 01:28 AM

Re: Sparkle 250W noise....

Usually the audible noise is caused by magnetic component (transformers, inductors) that are not well impregnate with varnish.
Another reason could be a modulation of the default switching frequency: usually it is above 25KHz, above human hearing, but if the SMPS it is not OK, it can oscillate and have a modulation at lower frequency.
Sometimes the modulation appears only at low or not load, this is due to the "burst mode operation" to reduce the consumption: the SMPS works at full frequency for short periods just to keep the output stable and than it stop until the voltage drop a little.

In your case "It works but... there is this noise from the p/s even when it is off (still connected to ac)" I would investigate the stand by section because it is the only part working when the SMPS is off with the AC input present. Check small lytics near stand by.
You can do a test: with the SMPS off put a load on 5V stand by and listen if the noise changes or disappears.

Ciao
Gianni

**ratdude747** · 08-07-2009, 03:11 AM

Re: Sparkle 250W noise....

some pics would help. maybe a PI coil's core is coming loose and needs a dab of hot glue.

**lucky13** · 08-14-2009, 11:30 PM

Re: Sparkle 250W noise....

Originally posted by Gianni

Usually the audible noise is caused by magnetic component (transformers, inductors) that are not well impregnate with varnish.
Another reason could be a modulation of the default switching frequency: usually it is above 25KHz, above human hearing, but if the SMPS it is not OK, it can oscillate and have a modulation at lower frequency.
Sometimes the modulation appears only at low or not load, this is due to the "burst mode operation" to reduce the consumption: the SMPS works at full frequency for short periods just to keep the output stable and than it stop until the voltage drop a little.

In your case "It works but... there is this noise from the p/s even when it is off (still connected to ac)" I would investigate the stand by section because it is the only part working when the SMPS is off with the AC input present. Check small lytics near stand by.
You can do a test: with the SMPS off put a load on 5V stand by and listen if the noise changes or disappears.

Ciao
Gianni

Gianni,

How big (approx ohms) a load do you suggest for the 5vsb rail?

Here are some pics....

So which one of the Jamicon/Teapo cap(s) are for 5vsb?

I can't read their values but they all seem to be 1uF/50V size...

Attached Files

**everell** · 08-15-2009, 05:46 PM

Re: Sparkle 250W noise....

What is the model number? Looks like an older Sparkle power supply.

**lucky13** · 08-15-2009, 07:26 PM

Re: Sparkle 250W noise....

Model is FSP250-60ATV.

Yes it is an older model.

**ratdude747** · 08-15-2009, 07:45 PM

Re: Sparkle 250W noise....

did you check that PI coil in pic 4?

**lucky13** · 08-15-2009, 09:19 PM

Re: Sparkle 250W noise....

Originally posted by ratdude747

did you check that PI coil in pic 4?

Hmm, what about that coil? It is standing up....

**lucky13** · 08-22-2009, 08:37 PM

Re: Sparkle 250W noise....

I am back at working on this...

I tried using a straw to listen in where the noise is coming from but w/o success.

I rolled up a piece of paper into a cone shape and point the smaller opening at the p/s PCB.

The noise seems to be loudest at the resistor?

As I was listening to this noise, I find the noise is not constant. It starts and stops but never completely stopped. Sometimes it is continuous. This is with just the ac cord plugged in and nothing connected to any of the output plugs.

So, what am I dealing with here?

Attached Files

**momaka** · 08-22-2009, 10:13 PM

Re: Sparkle 250W noise....

Try loading the 5vsb.
A 5 ohm resistor should pull 1 amp from that rail (as calculated by Ohm's law). Note that the resistor will then need to be capable of at least 5 watts. If you put a 10 Ohm resistor, you'll be pulling 0.5A from the 5vsb, and the resistor will need to be rated for at least 2.5 watts.
It's not that uncommon to have a high-pitched noise when 5vsb is unloaded. I have an older 188W Lite-ON PSU that always squeals. I believe the motherboard that it's powering is not pulling enough power from the 5vsb and that's why I can hear it.

Also while loading the 5vsb, measure its with a multimeter and report back with the results. If it's close to 5v and not out of spec (or near its limits), I would leave the 5vsb as is.
Or if you really want to know that 5vsb is working properly, look for a capacitor that is either 10uF, 22uF or 47uF (usually rated for 25v or 50v) and replace it with new, low ESR cap of the same specs. This should definitely make 5vsb work like new again.

**linuxguru** · 08-22-2009, 11:27 PM

Re: Sparkle 250W noise....

Yup, if +5Vsb is unloaded, the auxiliary flyback converter may squegg (i.e. operate in start-stop bursts). Although the normal switching frequency of the flyback converter may be inaudible, the squegging (which may be as low a 1kHz or lower) may well be audible.

**Wizard** · 08-23-2009, 10:50 AM

Re: Sparkle 250W noise....

That's on wrong side. (this is hot primary side), The assumed resistor would be on secondary side DC side.

The squeak is from transformer. Make sure the cap and resistor are NOT touchy-feely each other (this makes noise too if touching can happen!).

The fix for squeak is change capacitors for that 5Vsb as others had advised and I want to add one more, if you know of one with high vacuum chamber, put the transformer in small cup of varnish and pull a vacuum to pull gases/air out of transformer's internal construction. Then let it dry by baking in the junk oven on *very low temp*. Check often. This will give you best job of this transformer NOT to squeal due to loose bit vibrating internally.

I recently had to diagnose a squealing noise complaint because lady and toddlers can hear this from 52" rear proj. Noise was intermittent and we were lucky to catch this in the act second attempt next weekend later, I had back removed and waiting for it to talk and use a tube to pinpoint the source of noise. Stu heard squeal from his room (15 feet, and I'm deaf heh, but I do understand very well as I have hearing aids but cannot hear the high pitch range). Loud is my guess. Wow. Noise maker was emitting from flyback transformer. Working frequency is 32KHz because this is a chassis that upconverts any lower res (480 and 720 to 1080) and straight across for 1080 to 1080 therefore bypassing upconversion.

Cheers, Wizard

**lucky13** · 08-23-2009, 12:23 PM

Re: Sparkle 250W noise....

momaka/linuxguru

I don't have any power resistor at the moment to load the 5vsb line as you both suggest.

OTOH, when this p/s was connected to a p4 motherboard and power the ac only, the noise was there. So, I would think the mobo provides enough loading on th4 5vsb line right? Or no?

As best as I can see these small lytic caps, I think most are 1uF variety, except one sleeved in heat shrink tubing. C21 is 1uF/50V. Could this one sleeved be the "evil" cap I need to replace?

Attached Files

**lucky13** · 08-23-2009, 12:27 PM

Re: Sparkle 250W noise....

Originally posted by Wizard

Make sure the cap and resistor are NOT touchy-feely each other (this makes noise too if touching can happen!).

The fix for squeak is change capacitors for that 5Vsb as others had advised and I want to add one more, if you know of one with high vacuum chamber, put the transformer in small cup of varnish and pull a vacuum to pull gases/air out of transformer's internal construction. Then let it dry by baking in the junk oven on *very low temp*. Check often. This will give you best job of this transformer NOT to squeal due to loose bit vibrating internally.

Cheers, Wizard

I move the resistor, ceramic disc cap & diode ever so slightly to make sure they are all free standing. But the noise is still there :-(

Your suggestion makes sense to me but I don't have access to vacuum chamber or varnish to try your idea. That's out of my league.

**momaka** · 08-23-2009, 03:23 PM

Re: Sparkle 250W noise....

Originally posted by lucky13

OTOH, when this p/s was connected to a p4 motherboard and power the ac only, the noise was there. So, I would think the mobo provides enough loading on th4 5vsb line right? Or no?

Depends on the motherboard design, but since you said it's a p4 motherboard, it probably did.

Originally posted by lucky13

Could this one sleeved be the "evil" cap I need to replace?

Possibly, but I can't tell for sure with the sleeve on there. Also, looking at the center of this picture, it could be one of those 3 small caps as well.

**lucky13** · 08-23-2009, 05:13 PM

Re: Sparkle 250W noise....

Originally posted by momaka

Depends on the motherboard design, but since you said it's a p4 motherboard, it probably did.

Possibly, but I can't tell for sure with the sleeve on there. Also, looking at the center of this picture, it could be one of those 3 small caps as well.

Really? Oh shoot... The two on the north side are "F" caps.... I guess I will recap them. Just that since the Antec went Boom on me, I try not to disturb too much of the components on the PCB.

Well, nothing better than to tie up the series since I am at 0-1 on recapping P/S with "F" caps.

**Toasty** · 08-23-2009, 05:37 PM

Re: Sparkle 250W noise....

IMO, that could be an electrolytic cap cooking internally. Looks fine from outside, but has dried out and is breaking down internally. The sound you're hearing is arcing inside the can. Watch that 5vsb carefully.

Until you positively locate & identify the component causing the noise, I would not hook this into your system.

With an insulated stick or probe, while it's making the noise, try pushing on different components to see if the noise pitch or intensity changes.

Try using a paper towel tube to listen.

Toast

**lucky13** · 08-23-2009, 09:59 PM

Re: Sparkle 250W noise....

Darn!

I've now replaced ALL the other lytic caps on this p/s with Panasonic FC/FM caps:

C12 (sleeved one seen in the pix). It was a 4.7uF/50V Jamicon TK. I put in a 4.7uF/50V FC

C20 22uF/50V Teapo > FM 22uF/50V
C24, C22, C34 10uF/50V "F" TNR > 10uF/50V FM
C5, C6, C17, C21 1uF/50V Jamicon TK > 1uF/50V FM

I spotted 2 other small lytic caps in the output cluster of caps. They are both Jamicon 220uF/16V.

And the darn noise is still there!!!!

One thing I notice is that even I have unplug the ac cord, the noise is sustained for another 5-10 seconds before disappearing. So, this confirms it is a 5vsb issue. But what/where?

**Krankshaft** · 08-23-2009, 10:07 PM

Re: Sparkle 250W noise....

Could just be a winding on the standby transformer vibrating these things operate in the Khz range after all.

I had an old Sharp LCD projector 640 X 480 weighed 45 lbs no joke and the inverter buzzed not louder than the fan but loud enough to be heard if you listened carefully.

The PSU had an all Nichicon lineup and the ESR of the all caps were fine. I used a mechanics stethoscope and it was coming from the ballast transformer.

There was no way that I was going to remove it and dip it in varnish (a method to quiet noisy transformers with vibrating windings) the projector worked fine up until I sold it.

**momaka** · 08-23-2009, 10:49 PM

Re: Sparkle 250W noise....

Originally posted by lucky13

One thing I notice is that even I have unplug the ac cord, the noise is sustained for another 5-10 seconds before disappearing. So, this confirms it is a 5vsb issue. But what/where?

Nowhere I guess. You did replace all the small caps after all, so probably nothing to worry. Like I said earlier, my Lite-ON PSU does the same thing and it hasn't given me any problem at all. All major caps inside it are Japanese and the PSU itself is built very well. Came from a HP Pavilion 8756C computer with clogged vents and over 22000k hours of on time. That's more than enough to convince me it's good.

Try loading the 5vsb with a couple of fans and see if the noise goes away or becomes higher-pitched. Measure voltage as well.
Well either way, I still think it should be fine now.

Sparkle 250W noise....

Sparkle 250W noise....

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