Low POwer Output with TDA1562Q Please Help

[bubacka]

Hello.
Recently I have build this amplifier and I ran into a problem. it is supposed to give 55 watts RMS/4 Ohms, or 70W musical power on 4 ohms but it wong get as near as it is supposed to.
Compared to my rotel RB-971mk2 which is 80W per channel musical power this one sounds like half of it.
This amplifier is supposed also to be more powerful than Pioneer's
4 x 50 MOSFET, but it is not, check out the schematic for details.
The TDA1562Q has a supply voltage from 12V to 15V I powered it with 12.7V directly from car battery and it didnot give good results.
The IC has a diagnostic facility that whenever it gets near clip it temporary shuts down the output but in my case it happens when it is on 1/2 of the output power, and sometimes on lower volume.
I dont know what is the problem, PLEASE HELP.

datasheet of the TDA1562Q

[jsandvik]

Where did you get that chip?
I want to experiment with it too!

The ratings are measurde at 14,4V, you are running at 12,7.
That gives you a little less output, but does not explain why
it sound weaker than the pioneer mosfet.....

[Carondimonio]

Hi Bubacka,

did you try to measure the voltage at pin 16 during operation? you should get something above 10V, if not, your chip is running in class B only (20 W output power).

Cheers,

Bruno

[bubacka]

I got the chip from a local dealer of electronic components here in Skopje, Macedonia.
I measured pin 16 and read 11V, which means that it is running in class H but I dont know where the problem might be.
I even tried it on 15V but it is the same not enough power
When the amp is working on a lower volume it gives a nice and precise sound, a little bit shy in the lower range ( but i think it is because has not enough power to drive bass speakers) but as soon as I raise the volume it starts to get crazy with the clip and shuts down the output.
Any suggestions!
HELP HELP HELP

[bubacka]

Bruno what kind of tests should i do with dummy load?
with what kind of resistor (value) should i do tests for this amplifier
I am desperate to make this amp working properly.
My car speakers are JBL GTO series 100W rms 300W music power 4 ohms, but even on higher supply voltage i have the same power output myn car when engine rning produces 14.5 15 volts but the amp still refuses to give good results

[Carondimonio]

Hi Martin,

The dummy load should be 8 or 4 Ohm, 60- 70 W.
Use a signal generator at the input and start with a
very low level. Increase gradually the input level and
measure the output (possibly with an oscilloscope).
Look at which output level the amplifier starts clipping.

Another couple of dumb questions:
1. Do you use only one speaker at the output of each
amplifier, or did you connect two in parallel?
2. Does the chip get hot? How hot?
3. Did you use an adequate heatsink?

Cheers,

Bruno

[bubacka]

Bruno
The chip is not getting hot at all it is somewhere about normal room temperature, i used a little bit larger heatsinks than the specified ones, now when i measure the amp output i get somewhwre about 8 to 11 volts output according to the specs that is ok but it is weak, there must be a problem with the amp...........??? i dont know.
is there any way that i can get bigger power from this amplifier like bridging or something else???

[bubacka]

I measured the chip temperature after 2.5 hours working on full load, the temp was 32 degrees celsius, that temp is normal, the chip's limit is 100 deg. celsius, and again i checked the pcb and all parts they are ok but the power is still low
Any suggestions about this problem?

[Mr Teal]

Where did you get your TDA1562's? I'm interesting in playing around with them, but Digikey, Mouser and InOne don't seem to carry them.

[Carondimonio]

Hi Martin,

I confess I' m getting a bit confused...

Let' s see... in your e-mail to me you wrote that the output voltage, when measured between the two output terminals, is way too low. With which input voltage do you get these values?
How is your source connected?

Cheers,

Bruno