(Topic ID: 234834)

Space shuttle U47 sound amp gets very hot????


By Tbirdmatt66SS

4 months ago



Topic Stats

  • 6 posts
  • 2 Pinsiders participating
  • Latest reply 4 months ago by G-P-E
  • No one calls this topic a favorite

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#1 4 months ago

Hello. On my space shuttle, the U47 amp for sound on the heat sink gets very hot in a very short time. It has been replaced and I used thermo compound between it and the heat sink. CPU board is on the bench with a pc power supply providing 5v and +12 volts. What would be causing the amp chip to run so hot?
Thanks.

#2 4 months ago

4 ohm speaker versus 8 ohm speaker?

#3 4 months ago

There are no speakers connected at this time. Nothing is connected to the board except +5V and +12V

#4 4 months ago

With no load on that one there isn't much that can go wrong.
Shorted C25?
Abnormally high +12V supply?
Proper R72/R73?
Solder bridge between a couple adjacent pins?

Replaced with TDA2002 or TDA2003?
Where did the parts come from?

#5 4 months ago

I believe it was a TDA 2002. No soldier bridges. The voltage is good. I think I replaced c25. Perhaps r72/r73 need looked at as well as the other axial caps in the sound circuit? Maybe C28 and C29 are shorted?

#6 4 months ago

Where did the TDA2002 come from?
What type of cap at C25?
Nothing is plugged onto J15?

R72/R73 unlikely but weirder things have happened.
C26 would short out +12 supply and cut power to U47 - not this one.
C29 being shorted could introduce a DC offset into the amp. Yes, that can be bad but still not likely.

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