noise problem

vidc · 1st January 2010, 10:30 PM

hi all
i've built a simple guitar amp,with fet preamp and tda2030 power amp,with single power supply.the problem is when i turn on the amp it sounds really bad,i can't turn up the volume.but after aprox 10 minutes working like that, it starts working fine,and i can run it full power without any problem.the schematic for power amp is from tda2030 datasheet for single power supply.
for power supply i use my old notebook ac-dc adapter,voltage 19.5V,current 3.5A.has anyone experienced similar problem and does anyone know what it could be???

AndrewT · 3rd January 2010, 08:05 PM

post your schematic for the eft and the chipamp.
Post a pic of your assembly.
Label all the components and we'll show you what to measure to help us determine the source of the problem.

vidc · 5th January 2010, 05:51 PM

sorry for late reply,i totally forgot that i posted about my problem.anyway,i found the problem...it was wrong biased jfet,that in the end died while i was testing the amp with music playing from phones output of my computer .thank you anyway,

1st January 2010, 10:30 PM	#1
vidc diyAudio Member Join Date: Dec 2009	noise problem hi all i've built a simple guitar amp,with fet preamp and tda2030 power amp,with single power supply.the problem is when i turn on the amp it sounds really bad,i can't turn up the volume.but after aprox 10 minutes working like that, it starts working fine,and i can run it full power without any problem.the schematic for power amp is from tda2030 datasheet for single power supply. for power supply i use my old notebook ac-dc adapter,voltage 19.5V,current 3.5A.has anyone experienced similar problem and does anyone know what it could be???

3rd January 2010, 08:05 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	post your schematic for the eft and the chipamp. Post a pic of your assembly. Label all the components and we'll show you what to measure to help us determine the source of the problem. __________________ regards Andrew T.

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5th January 2010, 05:51 PM	#3
vidc diyAudio Member Join Date: Dec 2009	sorry for late reply,i totally forgot that i posted about my problem.anyway,i found the problem...it was wrong biased jfet,that in the end died while i was testing the amp with music playing from phones output of my computer .thank you anyway,

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