Bridged TDA2030A problem

[bigbeck]

I built the bridged amp from the data sheet schematic and have a case of severe motor boating. Seems like the speaker will blow if I leave it on for more than one second. It does this even if the guitar is not plugged in. If I disconnect the speaker,I can measure 14.5 VDC at the speaker out jack. I'm getting 17 volts at the + & - rails.

I'm thinking I may have fried the chip as I soldered two connections without a heatsink . What a dope

Prior to this build, I made guitar amps out of a single TDA2050 and TDA2030A. I had a few minor problems with them that have since been sorted.

Any ideas?


Don

 

[bigbeck]

Here's the schematic

TDA2030A datasheet(8/15 Pages) STMICROELECTRONICS | 18W Hi-Fi AMPLIFIER AND 35W DRIVER

 

[ampimp]

Hi
Did you use the pcb layout in the stmicro data sheet???
Ian

 

[AndrewT]

Hi,
where does the lower chipamp get it's inverted signal from?

 

[bigbeck]

Hi,
where does the lower chipamp get it's inverted signal from?

Not sure what you mean. It's built as per schematic. Is there an error on the schematic?

I built it on perf board so the layout is not the same as the data sheet.

I have a small temporary heat sink attached to the chips (20mm X 200mm X 3mm thick) and it gets too hot to touch in about 30 seconds - without the speaker attached.

 

[AndrewT]

If you don't understand Bridged operation then you should not be building bridged amplifiers from a design that has not been proved to work reliably and is recommended by trustworthy peers.

 

[bigbeck]

Andrew, do you see an error on the schematic? Still, I find it hard to believe that no one on this forum has built and tested that circuit.

Don

 

[picowallspeaker]

i did it...about 20 years ago !!! And I remember I blew two midranges
(so sweeeeet !) with it ...of course : too much current running !
As far as I can remember ... No good circuit for me 1
I preferred the much powerful version with four transistors plus two TDAs .
With a 100 W (always underrated !) 16+16 V supply ,that amp was a beast !

 

[AndrewT]

I can't see, on the poor copy of the schematic, where

the lower chipamp get it's inverted signal from?

 

[poynton]

Via a resistor from the output of the upper chip.



.

 

[sregor]

Inverting amp input is through R7. (Inverting amp has to cancel out the signal to the inverting input - it works.) (have seen other bridge amp circuits work like this) Regardless, OP has DC off set problems, and both amps, if working properly, should have no (or little) DC offset. Motor boating is most likely bad capacitor or bad connection, but more information is needed.

 

[bigbeck]

Is it possible that I cooked one of the chips? After all, I soldered two connections before I realized I didn't have a heat sink on the leads. I pulled the chips out and ordered new ones. Is there any way to test the chips out of circuit with a multi-meter?

Don

 

[bigbeck]

Think this is legit? All you need is a 12-0-12 100VA transformer,right?

http://cgi.ebay.com/Value-Choice-TD...264?pt=LH_DefaultDomain_0&hash=item4aa5263040

Edit: I really like the part about welding the components together. No problem there as I already have a 220amp welder. LOL

Don

 

[davidsrsb]

I built it on perf board so the layout is not the same as the data sheet.

I have a small temporary heat sink attached to the chips (20mm X 200mm X 3mm thick) and it gets too hot to touch in about 30 seconds - without the speaker attached.

Power amplifiers and perf board don't mix. Wiring inductance is very important as currents are high

 

[poynton]

...................................
Edit: I really like the part about welding the components together. No problem there as I already have a 220amp welder. LOL

Don

There are some words and phrases used in American which don't translate too well into real English so don't laugh too loud !!!!



.