Bizhub C308 Power Supply Humming Noise - Fuser

[engr]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

I can understand the perceived safety in a company withholding technical info, but I'm not sure if that really helps the company in the long run. Good techs may actually help the company figure out issues in the field and improve the product. Some of the best and most revered product lines have extensive support data out there. When the product is a decade old with no data or knowledge base, no one wants to take the risk so the product fizzles. Maybe that's the goal. But, for companies touting "eco friendly" and marketing such innovative features, it seems a counterproductive to be so remove/replace centered. They could make just as much selling OEM replacement parts for decades and providing schematics. Sorry to get on my soap box. I'll leave you with a video that explains my frustration.

The right to repair movement - YouTube

[allan]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

The manual contains schematics point to point wiring. Konica Minolta does not publish the diagrams thru there channels. Been repairing boards here and there. Been struggling with the power boars the control boards are much easier for me. If you know the diagnostics code it had on it you have a solid place to start looking. Kinda like the way the buzzing sounds.

Yea the electronics on these machines are top of the range stuff. Been amazed at how some of these machines go for 20 years plus of service.
I like tinkering with electronics by no means an engineer. Built a CNC plotter from printer parts that scribes off blue dykem 5 microns a pass. Used that to make motor driver PCB's with the driver chips from a copier for the NEMA 17 motors found in a document feeder. Fun stuff. Some PSU are easy to switch on only need a constant load from startup so just add a power resistor of the correct value.

So what is the plan hot glue? Silicone?

[engr]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

Allan, I've heard chokes make noises like this before and I usually start with a rubber band around it to see if it changes. Then hot glue is my go-to. I tried a rubber band with no difference. I ran out of time so I'll have to come back around to it later. I'll try gluing it, but it may eventually just get replaced (the inductor that is). The problem is I think it's part of a tank circuit which means the inductance value needs to be spot on to work right. It would be easier to just have a part number or value. I'll look closer. Here's the inductor I'm after.

20201127_194400_a (Large).jpg

[blackcat4866]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

Please let us know of your progress. =^..^=

[tulintron]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

Allan, I've heard chokes make noises like this before and I usually start with a rubber band around it to see if it changes. Then hot glue is my go-to. I tried a rubber band with no difference. I ran out of time so I'll have to come back around to it later. I'll try gluing it, but it may eventually just get replaced (the inductor that is). The problem is I think it's part of a tank circuit which means the inductance value needs to be spot on to work right. It would be easier to just have a part number or value. I'll look closer. Here's the inductor I'm after.

[ATTACH=CONFIG]47460[/ATTACH]

Engr and all folks, good afternoon.I'm sorry for the English, because I'm Brazilian.


I also love electronics and I found the comments on this topic sensational.


I managed to cause a hum in the power supply, replacing only the drum in the unit, for a drum in line 4.
Internally I don't know the difference because I don't have one from line 8 to open. But when I remove the drum from line 4 and return with the drum from line 8, the buzz at the source simply disappears.

[engr]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

Tulintron, that's interesting. I'm not sure what line 4 and 8 are, but it's interesting that the drum can affect the power supply noise.

Do you guys know what the resistance across the fuser heating element should be? When I first checked it, I thought it was incredibly low, but after disassembling, I don't find anything that looks out of whack. One element was about 2.5 ohm, the other was maybe 1.5 ohm. That's a lot of current!

[tsbservice]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

Engr and all folks, good afternoon.I'm sorry for the English, because I'm Brazilian.


I also love electronics and I found the comments on this topic sensational.


I managed to cause a hum in the power supply, replacing only the drum in the unit, for a drum in line 4.
Internally I don't know the difference because I don't have one from line 8 to open. But when I remove the drum from line 4 and return with the drum from line 8, the buzz at the source simply disappears.

tulintron very interesting but as usual I expect that from you.
You mean you only swapped cylinders and that cures humming?
Take care buddy.

[allan]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

Would guess it makes use of active power factor correction?

[tulintron]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

tulintron very interesting but as usual I expect that from you.
You mean you only swapped cylinders and that cures humming?
Take care buddy.

Yes, Tsb. As you know, we always do internal tests in our laboratory. In view of the tests, we noticed that if a drum of line 4 is mounted in a unit of line 8, the power supply has a humming noise. When I return the correct drum, the buzzing disappears.

Engr, I'll try to be brief, but the lines I referred to the models:


Line 4 - C224, C284, C364
Line e - C224e, C284e, C364e
Line 8 - C258, C308, C368

Detail:
In my case, the noise only appears when the printer goes into a print job. But the noise is exactly at the power supply

[allan]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

By drum do you mean fuser roller?

[tulintron]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

By drum do you mean fuser roller?

No, Allan. Here we change the drums of the Drum Units.

I know the problem with Engr. is in the fusion.
I just wanted to notify you that in my case, I managed to cause a hum in the power supply using a C364 drum in a C308 drum unit

[M1963]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

greeting,
i need a power supply shematic diagram for c308
does anyone know where it can be obtained.
thank you

[DelawareJim]

Re: Bizhub C308 Power Supply Humming Noise - Fuser

Jim in Dover Delaware chiming in. I am in no way an engineer, just a Konica Minolta copier tech for 30 years. If you listen closely, you can hear that annoying "buzz" sound on just about every copier that we service. If it annoys the customer, we make the copier go into energy save/ sleep mode after a few minutes. Another fix is to cut to size a soundproof tile, remove the outer metal covering from the power supply and insert the cut tile and reinstall the metal cover. This absorbs most of the buzz noise. We have had excellent results with that. I would say 75-80% reduction in noise. Also, several times we have had the customer pay an electrician to install a dedicated 20A outlet for the copier. That really helps. It could be the copier is "starved" for current. A dedicated 20A outlet really does the trick. We have also noticed, if you have digital line filter installed, remove it and plug the copier directly into the outlet, the noise will become much less.
To check out the tiles we use, go to Amazon and paste this into the search bar "Sound Proof Sound Panels - 8 Pack 12" X 12" X 0.4" Acoustic Foam With Adhesive Stickers, Sound Absorbing Panels for Music Recording Studio Equipment, Home Sound Insulation A2S". They cost 29 bucks for a case and work great. One case of 8 tiles will take care of about 25 to 30 machines. We don't use any adhesive or tape for the install. They stay in place just fine.