tda2040 hum problem

DIY_Peter · 23rd April 2004, 06:26 AM

I've built one channel of a chip amp using the tda2040. I used the standard schematic that's on the datasheet.

I used a 15-0-15V 225VA toroid.

It plays, but there is some hum. When I disconnect the source and touch the metal case of the volume pot, I even pick up a radio station. Ok, this is actualy great, because now I have a receiver you would say ... But that was not the intention

I used star grounding. All ground wires, including the central tap of the toroid, go to a central bolt that's connected to the metal chasis.

Because I had hum, I tried a ground loop breaking circuit, as discribed on the ESP site. But it stays the same.

I'm probably the N-th guy that asks a question like this, but I can't find a good answer in previous posts.

officeboy · 6th July 2004, 11:09 PM

I also have this problem on an amp I'm building. it even does it when the source is connected.
I think it's my potentiometers grounding to the chasse.

Not really sure how to isolate it. Maybe I’ll try tying the input ground directly to the case? Maybe some better pots would take care of it too.

BlackDog · 6th July 2004, 11:33 PM

Try a 220pF ceramic cap. across the chip's signal inputs. It worked for me, and I live next to the local radio transmitter....!

metal · 7th July 2004, 12:24 AM

Hello

It might be because of that there are close triacs working on the mains. That can be solved using some kind of mais filter.

Kind Day

carlosfm · 7th July 2004, 12:35 AM

Try a 1 to 2.2 ohm resistor from signal star ground to power ground.

Oh you have two problems: one is hum.
A pic would help.
The other one is that your amp is a good antenna.

Try the above.

BlackDog · 7th July 2004, 02:07 AM

FYI,

The cap on the inputs fixed both some obvious radio reception, AND some hum that was there as well.

chris ma · 7th July 2004, 04:39 PM

Quote:

Originally posted by carlosfm
Try a 1 to 2.2 ohm resistor from signal star ground to power ground.

Oh you have two problems: one is hum.
A pic would help.
The other one is that your amp is a good antenna.
Try the above.

With what wattage for such a resistor Carlos? 10Watt or 20Watt?
Thanks in advance,
Chris

carlosfm · 7th July 2004, 06:00 PM

Quote:

Originally posted by chris ma
With what wattage for such a resistor Carlos? 10Watt or 20Watt?
Thanks in advance,
Chris

1/4w.

I'm talking signal ground.
Small resistor.

23rd April 2004, 06:26 AM	#1
DIY_Peter diyAudio Member Join Date: Feb 2003 Location: Leuven	tda2040 hum problem I've built one channel of a chip amp using the tda2040. I used the standard schematic that's on the datasheet. I used a 15-0-15V 225VA toroid. It plays, but there is some hum. When I disconnect the source and touch the metal case of the volume pot, I even pick up a radio station. Ok, this is actualy great, because now I have a receiver you would say ... But that was not the intention I used star grounding. All ground wires, including the central tap of the toroid, go to a central bolt that's connected to the metal chasis. Because I had hum, I tried a ground loop breaking circuit, as discribed on the ESP site. But it stays the same. I'm probably the N-th guy that asks a question like this, but I can't find a good answer in previous posts.

7th July 2004, 12:24 AM	#4
metal diyAudio Member Join Date: Jan 2004	Hello It might be because of that there are close triacs working on the mains. That can be solved using some kind of mais filter. Kind Day __________________ any way, finally...

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
PSU using TDA2040 ?	poynton	Power Supplies	7	10th February 2012 03:48 PM
mtx amp problem [[help!!]]	fuzzypinkhat45	Car Audio	3	8th July 2008 05:34 AM
I need help with a pot problem.	Harderror	Class D	8	16th December 2006 04:04 PM
TDA2040 Amp	Fritzell	Chip Amps	0	20th July 2004 03:31 PM
Did the TDA2040 pan out?	KT	Chip Amps	0	6th May 2004 04:47 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

6th July 2004, 11:09 PM	#2
officeboy diyAudio Member Join Date: Nov 2003 Location: NW Washington	I also have this problem on an amp I'm building. it even does it when the source is connected. I think it's my potentiometers grounding to the chasse. Not really sure how to isolate it. Maybe I’ll try tying the input ground directly to the case? Maybe some better pots would take care of it too.

6th July 2004, 11:33 PM	#3
BlackDog diyAudio Member Join Date: Feb 2004 Location: Wellington, New Zealand	Try a 220pF ceramic cap. across the chip's signal inputs. It worked for me, and I live next to the local radio transmitter....!

7th July 2004, 12:35 AM	#5
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	Try a 1 to 2.2 ohm resistor from signal star ground to power ground. Oh you have two problems: one is hum. A pic would help. The other one is that your amp is a good antenna. Try the above.

7th July 2004, 02:07 AM	#6
BlackDog diyAudio Member Join Date: Feb 2004 Location: Wellington, New Zealand	FYI, The cap on the inputs fixed both some obvious radio reception, AND some hum that was there as well.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)