Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

TDA7293 Amplifier Design Blows Up Instantly
TDA7293 Amplifier Design Blows Up Instantly
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
Reply
 
Thread Tools Search this Thread
Old 24th October 2018, 08:17 PM   #31
Mark Whitney is offline Mark Whitney  Netherlands
diyAudio Member
 
Mark Whitney's Avatar
 
Join Date: Feb 2013
Location: Netherlands
Quote:
Originally Posted by jan.didden View Post
A voice of reason, shortly to be drowned out again by the un-reasoned shouters ;-)


The guy wants help with his implementation. You don't help with just shouting personal opinions of what is good or wrong, which in itself may be totally wrong.
Please assist him, if you can't bugger off.

Jan
Where do you suggest he should begin?
__________________
Regards Mark.
  Reply With Quote
Old 24th October 2018, 09:28 PM   #32
googlyone is offline googlyone  Australia
diyAudio Member
 
Join Date: Nov 2006
Location: Adelaide, South Australia
TDA7293 Amplifier Design Blows Up Instantly
Experience says you would be well advised pulling the fuses to the TDA chip, and replacing them with say 100 Ohm resistors. (A neat way is to solder 100 ohm resistors across blown fuses).

This will let you try powering the thing up (without a load) and checking you can get it to run OK unloaded.

If you have a serious issue like a short, or oscillation going bonkers, or outputs connected fighting one another, worst case you will see smoke from the resistors.

I dont guarantee 100 Ohms is ideal, but in my experience most power amplifiers will happily run with 100 ohms in each rail if not loaded.


The only other hint I offer (given all the other advice) is strip the thing back to the utter minimum that ought to work. Don't be shy, pull bits out till you can at least get the tiniest part working.

If the tiniest part doesn't work, well, drink some coffee and nut it out.

Then start adding bits back until those 100 Ohm resistors do something interesting.
  Reply With Quote
Old 24th October 2018, 11:03 PM   #33
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Originally Posted by jan.didden View Post
A voice of reason, shortly to be drowned out again by the un-reasoned shouters ;-)


The guy wants help with his implementation. You don't help with just shouting personal opinions of what is good or wrong, which in itself may be totally wrong.
Please assist him, if you can't bugger off.

Jan
Agree.
So here is my suggestion: if the OP wants to build a parallel TDA7293 power amplifier, (fine with me), then he must buy a parallel TDA7293 power amplifier kit, with a ready made and tested PCB, an amp which has been professionally designed and tested and where bugs have been ironed out.

Any new project takes some development time and effort; if he adds to his workload also designing and making a PCB, creating a good, stable layout , etc. , he will probably bite more than he may chew.

Hey, I have been designing and building amplifiers for ages, lots of them, and STILL new projects show one problem or another which needs correcting, or at least adjusting.
And I am not ashamed in the least to recognize that, it´s part of the job reality.

As a side note, I *hate* paralleling chipamp outputs ... extend that to any "perfect voltage source" type amps, including discrete ones, and the reason should be self evident.
__________________
Design/make/service musical stuff in Buenos Aires, Argentina, since 1969.
  Reply With Quote
Old 24th October 2018, 11:04 PM   #34
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by JMFahey View Post
As a side note, I *hate* paralleling chipamp outputs ... extend that to any "perfect voltage source" type amps, including discrete ones, and the reason should be self evident.
Then why not bridge a pair ?
That is much more forgiving so long as you get the speaker impedance right.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 25th October 2018, 08:08 AM   #35
FauxFrench is online now FauxFrench  France
diyAudio Member
 
Join Date: Dec 2017
Location: The mountains, calm and quiet.
There are apparently many skilled people ready to help but I get the feeling the OP has left the thread. Problem solved or giving-in?
My approach would be to test the board connections without any TDA7293 inserted. When the board with all the passive components inserted has been approved, to insert the master TDA7293 and test without a load and at low supply voltage. Only when the master works, I would try to implement the slave.
But, without the OP it may be futile.
  Reply With Quote
Old 25th October 2018, 08:46 AM   #36
marco1601 is offline marco1601
diyAudio Member
 
Join Date: Jul 2018
Quote:
Originally Posted by FauxFrench View Post
There are apparently many skilled people ready to help but I get the feeling the OP has left the thread. Problem solved or giving-in?
My approach would be to test the board connections without any TDA7293 inserted. When the board with all the passive components inserted has been approved, to insert the master TDA7293 and test without a load and at low supply voltage. Only when the master works, I would try to implement the slave.
But, without the OP it may be futile.
I have definitely not left the thread and neither solved my problems nor given in. I have not yet been able to find the time to make further progress and have only read all the input here with much interest. I will report back as soon as I have got new infos which will be very soon!
  Reply With Quote
Old 25th October 2018, 12:25 PM   #37
FauxFrench is online now FauxFrench  France
diyAudio Member
 
Join Date: Dec 2017
Location: The mountains, calm and quiet.
Thanks Marco for your confirmation. When you have time again, please let us know.
I believe you can get it to work but need a different approach than mounting everything and try to look for flaws on a board that has had a serious fault. You probably don't need us all to give you advises going in different directions so when you start again, choose a few as advisers.

I believe most of us were not aware that you try to implement a master/slave configuration that is rare but described by ST in the datasheet. Without knowing that particular option, your schematics appeared somewhat dodgy.
  Reply With Quote
Old 25th October 2018, 12:47 PM   #38
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
TDA7293 Amplifier Design Blows Up Instantly
Quote:
Originally Posted by jan.didden View Post
A thought: if the -supply is disconnected, how can it then blow up? Where is that 'blow up current' going to/coming from? Whats the path? Presumably from +supply but where to? Is there a ground connection at the chip, except for the standby pin?
Are we sure there are no other errors??

Edit: I see JMFahey has already pointed them out. Problem identified and diagnosed.

Jan
While testing, and assuming that the LS may be in the fault current path, it may be helpful to add a capacitor in series with the LS. You can start with a small one (maybe 10uF) and progress upwards. It also is then possible to measure the amplifiers offsets, and see possible DC-paths between the two amplifiers.

Note: with the amplifier outputs parallel (as here ) use two capacitors.

P.s.: A resistor in series with the capacitor may also be helpful.

Last edited by FdW; 25th October 2018 at 12:52 PM.
  Reply With Quote
Old 25th October 2018, 12:55 PM   #39
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
TDA7293 Amplifier Design Blows Up Instantly
Quote:
Originally Posted by FauxFrench View Post
There are apparently many skilled people ready to help but I get the feeling the OP has left the thread. Problem solved or giving-in?
My approach would be to test the board connections without any TDA7293 inserted. When the board with all the passive components inserted has been approved, to insert the master TDA7293 and test without a load and at low supply voltage. Only when the master works, I would try to implement the slave.
But, without the OP it may be futile.
Using a simulator, to calculate voltage values, may be of help here, one does not need a model for the amplifier to do this.
  Reply With Quote
Old 27th October 2018, 02:33 AM   #40
nigelwright7557 is offline nigelwright7557  United Kingdom
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by CharlieLaub View Post
The TDA7293 ICs have the tendency to blow up if the negative rail disconnects for any reason or at any instant in time when the chip is powered up is not the most negative connection to the IC. Also, if you install the bootstrap capacitor backwards (eg polarity of cap is backwards) this can happen.

See if you can check for these problems in your amplifier.

There is more info on the web about these kind of issues with the TDA7293 if you search for it.
I had a problem with the tda popping loudly in the speaker if the negative rail went first. I designed a hybrid valve/tda circuit and put the heaters from the +ve supply. Of course on power down the +ve supply went first and the tda would give a big thump through the speaker.
So I changed heater to be on -ve rail and this fixed the problem.

I also use 120R power resistors in power leads on first power up.

I also made a mistake mounting the tda right down on the pcb.
This caused the front pins to short on the rear pins pads on the pcb !
I desoldered the old tda and soldered in a new one about 2-3 mm above the pcb and everything was fine.
__________________
PCBCAD51 pcb design software. 2018 version out now with lower prices >> http://www.murtonpikesystems.co.uk
  Reply With Quote

Reply


TDA7293 Amplifier Design Blows Up InstantlyHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
TDA7293 parallel design DIY hydrovac Chip Amps 8 31st May 2015 11:07 AM
Fuse blows instantly Divad89 Tubes / Valves 21 6th June 2012 08:35 PM
NAD 3240 PE Stereo Amplifier Blows Fuses Immediately riffdex Solid State 2 3rd June 2012 03:02 AM
Car amplifier blows - help viki Solid State 11 21st September 2004 01:36 AM
Sony amplifier blows - HELP viki Car Audio 2 19th September 2004 11:07 PM


New To Site? Need Help?

All times are GMT. The time now is 07:34 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki