Fan buzz progressive dynamics 4645-

[tpi]

I've installed two of these converters (orig and replacement). Both exhibit buzzing variable speed fans.

1. Nothing wrong with the fans themselves-when they operate, they're quiet.
2. Occurs when converter is producing about 10 amps and fans are cycling off and on.
3. Occurs when the fans cycle off, and have stopped turning.
4. At that point fans are acting like a speaker-producing approx 60 cycle buzz.

Evidently there is still some power applied to fans, even when not turning. That power is evidently not well filtered.

The fans are 12V DC Sunon computer fans. Both converters were functionally normal.

Wondering if you can think of any electrical solutions? How about a filter capacitor across the fans? If so what value (sounds like about 60 HZ noise)?

Thanls_

[tpi]

I installed a Noctua fan in the front position. These are a premium priced case fan, supposedly quiet, and have rubberized mounting points which may cut noise.

Not thoroughly tested-but I confirmed it worked. Running on generator is not quiet enough to judge sound of converter fans. It takes a camping trip for that.

The Sunon remains in the rear position, cools big heatsink and blows air into the case from a side vent. The front fan (installed Noctua) expels air from the case through front vent.

The Noctua Fan requires slightly higher voltage to start. It appears the sensor for the fans is on the heatsink. Therefore the Sunon (rear) fan starts and runs prior to starting of the new front Noctua fan. In fact it's duty cycle appears to be greater now and may operate in a cleaner quiet zone of speed. The front fan will come on if things warm up sufficiently.

These are 80 MM computer case fans. The PD factory fans have two wires. Many other case fans have three or four wires. The extra wires are used for tachometer or speed control (or both). The Noctua fan is four wire fan. The black is ground and the yellow is 12 volt for those who want to run it from the two wire terminals on the PD board.

Anyway this is not real useful for reporting a solution to the noise, but may be useful as background info..

[wtxdxer]

I've wondered if a different fan may not buzz. I also have the Sunon fans. My WFCO 8955 that I took out has an NSTECH fan. I never did hear it buzz. I just did a search for that fan and the only results were web sites with a bunch of Chinese characters. Plus it has a different size connector on it so I can't do a direct replacement to give it a try.

[tpi]

Found several threads on computer enthusiast forums with similar issue with noisy fans. It occurs when the fans are used with case fan controllers-and operated at low speed-with humming and clicking. Some have reported success by trying other fans (or controllers). Since these fans are cheap and the front fan is easy to swap out, I've ordered a couple more to try of different mfg. The rear fan depends on any success with front fan as it requires quite a bit more disassembly.

[tpi]

I'm interested in how it goes.

Mine has Sunon fans. Evidently these brushless fans have a small switching power supply to operate them built into the fan. Then whatever is driving the fans may not be well filtered power supply. Result is at fan startup clicking and humming.

I'd be tempted to try a large filter capacitor but have some concerns about unusual loads for the fan driver. Possibly other fan mfg would start up more silently than the Sunon fans-perhaps the humming and noise is being generated in the fan itself-just a sign of running far under the specified voltage.

Almost anything covers up the fan sounds at this point-AC, traffic noises etc. But in silent conditions it is noticeable.

[wtxdxer]

I received my replacement fan with the capacitor across the leads today. Quick service! The capacitor they installed on mine is a 470uF 25v.

I've installed the fan but I need run down the battery some and charge it to get the fans to come on and see if they are any quieter. Hopefully the capacitor did some good.

[tpi]

After some usage, I can report it didn't get all the noise out-it did reduce it by more than half. You may want to experiment with capacitor size. Seemed like I settled on a 2600 uF capacitor across the fan-by switching the capacitor in and out and comparing sound. I have not tried a much larger capacitor..Be careful when experimenting with the fan. The fan's power is less than 12 volts, but to ground it gave me a little bite.

Otherwise I like the power supply. If someone has success with a much larger capacitor I'll try that. If not, I may determine how fast the fan runs under full supply output and simply have the fans switch on with 120 volt power (possible relay or wall wart-possible fans in series) and run continuously at that speed. To me the intermittent humming and clicking sounds are less desirable than a steady fan whir. As it stands, the fans have only run up to about half the time at a very low speed-but then I've only drawn about 15 amps max from the power supply. Both fans are in parallel FWIW.

On my unit, the fans are completely silent at output of about 5-6 amps or less. I have not had enough load on the supply for the fans to run continuously (which also stops the objectionable sounds).

[dougrainer]

wtxdxer wrote:
Thanks for posting this information. I installed a 4655 on Saturday and it has the same problem.

I called Progressive Dynamics this morning and spoke to a service tech. He said the buzzing was normal. I inquired about a capacitor across the fan leads and he said I could send the converter in and he'd install a cap on the circuit board. Then I referenced this forum post about getting a new fan with the cap installed and he said I'd have to speak to the service manager.

The service manager agreed to send a new fan with the capacitor installed.

I asked the service tech why they don't just install a capacitor on all the units at the factory and he said that was above his pay grade. I took a look at the WFCO 8955 I removed and found it has a 220 uF cap across the fan lead connector so I don't know why Progressive can spend $0.10 on a cap and put on theirs!

Regards, Alan

Because companies try to minimize their costs. Sorry, it is not just $0.10 in cost. You must purchase them and pay for their install. THAT costs money and building millions of these converters will save Tens of Thousands of dollars. What you have is not a defective product, just an annoyance and for the few picky customers they will adapt them. Years ago, Auto/Truck makers dropped installing grease Zircs on their vehicles because doing so saved them millions over the years. Doug

[wtxdxer]

Thanks for posting this information. I installed a 4655 on Saturday and it has the same problem.

I called Progressive Dynamics this morning and spoke to a service tech. He said the buzzing was normal. I inquired about a capacitor across the fan leads and he said I could send the converter in and he'd install a cap on the circuit board. Then I referenced this forum post about getting a new fan with the cap installed and he said I'd have to speak to the service manager.

The service manager agreed to send a new fan with the capacitor installed.

I asked the service tech why they don't just install a capacitor on all the units at the factory and he said that was above his pay grade. I took a look at the WFCO 8955 I removed and found it has a 220 uF cap across the fan lead connector so I don't know why Progressive can spend $0.10 on a cap and put on theirs!

Regards, Alan

[YC_1]

Sounds like you are not the only one that had this issue. Excellent support.

[tpi]

I'm answering my own question for future reference. Wrote to PD and got most helpful answer.

Evidently I'm operating it at a range where the fans are barely on and barely off. Fan completely off doesn't hum or fan completely on doesn't hum. Just a narrow intermediate range before fan actually starts turning.

PD is sending me a fan with a capacitor attached. 220uf @ 25 volt. The fans are in parallel-only one capacitor needed.

Very pleased with the support from PD.

[YC_1]

I suspect you are hearing transformer lamination buzzing. If you can disconnect the fans check with them out of the circuit.