Re: Powered Speaker Hum When Plugged In
Tried the external transformer. Same hum.
I don't know what to try next. Replace the smaller caps around the larger one?
By pass the on-off switch / volume control (defective)?
John
craftech
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Last Activity: 04-15-2021, 05:23 AM
Joined: 03-19-2006
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Re: Powered Speaker Hum When Plugged In
There are only two leads coming out of the secondary. Decal says 15v 1A Red - Red
John...Leave a comment:
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Re: Powered Speaker Hum When Plugged In
I thought about unsoldering the two 15vAC transformer secondary leads from the PCB and connecting the 16vAC output of a doorbell transformer to the PCB to see if it hums. I also have a Lionel transformer that puts out around the same amount of AC volts from fixed terminals on it.
If that works, they sell AC to AC wall wart adapters that are 1A 15vAC.
Thoughts?
John...Leave a comment:
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Re: Powered Speaker Hum When Plugged In
Yes. Plug in the power cord. Put it close to your ear. It hums. Turn it on. Hum is louder and does not vary with volume knob.
John...Leave a comment:
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Re: Powered Speaker Hum When Plugged In
Would a capacitor cause a hum with the unit powered off, but merely plugged in? I know it gets louder when the amp is turned on and the volume of the hum is constant when it is turned on, but it is present (but low volume) with the on-off / volume switch [B]off[/B] when you put it up to your ear as soon as you plug the unit in.
JohnRe: Powered Speaker Hum When Plugged In
Would a capacitor cause a hum with the unit powered off, but merely plugged in? I know it gets louder when the amp...Last edited by craftech; 04-10-2021, 12:53 PM.Leave a comment:
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Re: Powered Speaker Hum When Plugged In
I don't think it is rattling. It is mounted on a piece of gasket material and the screws are covered with a resin. It's not old so I don't think the laminations are loose.
I can hear it with the unit plugged in (but turned off) if I listen close and louder when I turn it on.
John...Leave a comment:
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Re: Powered Speaker Hum When Plugged In
I am pretty sure the hum is coming from the transformer.
Is there a reasonable supplier for a replacement?
I don't know the specs. The sticker says BDT-48A002(SP3)
Shenzhen Xingyaoda Electronics Not sure if that helps though?
Output 15V 1A
Two red wires out
JohnLast edited by craftech; 04-09-2021, 07:54 PM.Leave a comment:
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Re: Powered Speaker Hum When Plugged In
No change. Both RCA inputs and the 1/8" input as well.
In diagram 4 that I posted the terminal on the right is the 115V / 230V selector slide switch. I don't see any soldering issues. ??...Last edited by craftech; 04-03-2021, 04:55 PM.Leave a comment:
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Re: Powered Speaker Hum When Plugged In
The positive terminal? I tried grounding all the negative terminals yesterday....Last edited by craftech; 04-03-2021, 04:29 PM.Leave a comment:
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Re: Powered Speaker Hum When Plugged In
No...Leave a comment:
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Re: Powered Speaker Hum When Plugged In
I should have indicated that in the OP. (I'll add it in) Sorry can't edit the OP any longer.
The powered speaker set plays perfectly. It's just the hum you can hear when there is no music or quiet music and even when it is off but plugged in.
But they sound great.
Thanks,
John...Last edited by craftech; 04-03-2021, 03:25 PM.Leave a comment:
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Re: Powered Speaker Hum When Plugged In
DMM set to Diode:
Blk lead of DMM to + of Bridge Rectifier
Red lead to each AC leg of Bridge Rectifier
Both read .486 V
Red lead of DMM to - of Bridge Rectifier
Blk lead to each AC leg of Bridge Rectifier
Both read .488 V
My understanding is that between .4v and .6v are OK
John...Last edited by craftech; 04-03-2021, 02:39 PM.Leave a comment:
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Re: Powered Speaker Hum When Plugged In
Actually, when I was experimenting to find the cause I disconnected the wires and separated the chassis from the speakers, then ran them to their jacks and the hum was still there. I kind of thought it was the transformer or the transistor (IC) mounted on the heatsink.
John...Last edited by craftech; 04-03-2021, 12:07 PM.Leave a comment:
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Re: Powered Speaker Hum When Plugged In
Here is the PCB (Note: the red wire is a mod the guy who wrote the article did to bypass the amp to make then passive}
[url]https://blog.jonandtina.net/uploads/IMG_0301.png[/url]
External view:
[url]https://media.guitarcenter.com/is/image/MMGS7/StudioPro-3-Desktop-Audio-Monitors/603709000000000-00-500x500.jpg[/url]
My photos: (NOTE: The only large cap is the one I replaced that wasn't blown) None of the caps look like they are bulged or leaking. The brown smears are phenolic glue...Last edited by craftech; 04-03-2021, 10:53 AM.Leave a comment:
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Powered Speaker Hum When Plugged In
M-Audio Studiopro 3 Relatively inexpensive powered speaker set.
Produces 60 HZ hum. Thought it was only when turned on regardless of volume, but it can be heard through headphone jack and when you put the speaker next to your ear as soon as you plug it in. There is one large cap which I replaced. Checked solder joints on bottom of PCB. Re-soldered a few (which actually looked OK).
Hum still there.
[url]https://usermanual.wiki/M-Audio/MAudioStudiopro3UsersManual412393.1433470494/html[/url]
Any ideas?
Thanks,
JohnM-Audio StudioproLast edited by craftech; 04-03-2021, 10:10 AM. -
Re: Adding fans to Panasonic Plasma
Sorry I didn't get back to this earlier. Forgive my manners.
Thanks for the suggestion AndrewLeave a comment:
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Adding fans to Panasonic Plasma
Hi,
Recently replaced SC and surrounding boards on a Panasonic TC-P42X1 due to standard 7-blink failure code. There are no cooling fans on that model. Searched the forum for a mod to add them, but didn't find one. Forgive me if I didn't look hard enough, but does anyone have any suggestions on how to do that. I have quite a few quiet computer case fans. Zip ties and a separate power supply blowing in maybe?
Thanks,
John -
Re: Vizio VO320E Bad Power Supply Board
Follow-up
I received the Main Board from John (johnboy1313) and installed it [B]using my original power supply.[/B]
It worked like a charm. Tested it for 15-18 hours and it performed flawlessly.
My Main Board sticker was 3632-0842-0150 (6G) and John's was 3632-0842-0150 (6B)
The imprinted number on the circuit board for both
main boards is 0171-2271-2846.
His power supply was a little different which is why he recommended I use my original one. My power supply is 0500 - 0407...Leave a comment:
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Re: Vizio VO320E Bad Power Supply Board
Thanks for the reply Tom. I was just wondering about reprogramming the EEPROM. I searched these forums and found a post where a forum member purchased a programmer here:
[url]http://www.mcumall.com/comersus/store/comersus_dynamicIndex.asp[/url]
But then you need the bin file.
Apparently the replacement EEPROMS are pre-programmed.
Anyway,
Johnboy1313 is selling me his Main Board and Power Board from his broken set. I cannot thank him and the rest of you who were kind enough to...Leave a comment:
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Re: Vizio VO320E Bad Power Supply Board
I was wondering. Is there any chance that the power surge zapped the data on the EEPROM and didn't damage it.
If so, I see a USB port on the Mainboard. Can the EEPROM be "reprogrammed" and if so, how?
JohnLeave a comment:
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