Problems with piggy backed TDA1541

Dr.H · 21st May 2002, 02:33 PM

Hi All,
I have piggybacked two TDA1541 DAcs (one an A1, the other an S1). All pins are connected to each other, except for the pins requiring the connection of a 680pF cap. Both DACs have their own 680pF cap (the original DACs 680pF cap is surface mounted, while the added DACs 680pF cap is a leaded polyester cap).

Problem: After the CD player is switched off, the DAC will take up to 20 minutes to produce sound from the left channel, while teh right channel during this period is completely distorted. After up to 20 minutes have passed, a popping sound occurs on the right speaker and everything is fine, with great sounding music!

The powersupply is TL431 based, preceded by LM317/337 regulators for both +_5 and -15V. Any ideas on what can be causing this problem?

Many thanks
Ryan

Dr.H · 23rd May 2002, 12:56 PM

It appears that teh TL431 to teh -15V line was not able to handle TWO -15V pins. The calcs suggest that it jsut about could, but reality was another story. Put another T431 circuit in and problem is sorted out!

rbroer · 24th May 2002, 07:30 AM

You could have lowered the current to the 431.
It only dissipates the current that's being shunted, not the current required for the load.
You have to make sure both voltages are the same.
What are your experiences ? Better dynamics with some loss of fine level details ?

21st May 2002, 02:33 PM	#1
Dr.H diyAudio Member Join Date: Apr 2002	Problems with piggy backed TDA1541 Hi All, I have piggybacked two TDA1541 DAcs (one an A1, the other an S1). All pins are connected to each other, except for the pins requiring the connection of a 680pF cap. Both DACs have their own 680pF cap (the original DACs 680pF cap is surface mounted, while the added DACs 680pF cap is a leaded polyester cap). Problem: After the CD player is switched off, the DAC will take up to 20 minutes to produce sound from the left channel, while teh right channel during this period is completely distorted. After up to 20 minutes have passed, a popping sound occurs on the right speaker and everything is fine, with great sounding music! The powersupply is TL431 based, preceded by LM317/337 regulators for both +_5 and -15V. Any ideas on what can be causing this problem? Many thanks Ryan

23rd May 2002, 12:56 PM	#2
Dr.H diyAudio Member Join Date: Apr 2002	Problem solved It appears that teh TL431 to teh -15V line was not able to handle TWO -15V pins. The calcs suggest that it jsut about could, but reality was another story. Put another T431 circuit in and problem is sorted out!

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24th May 2002, 07:30 AM	#3
rbroer diyAudio Member Join Date: Mar 2002 Location: Netherlands	You could have lowered the current to the 431. It only dissipates the current that's being shunted, not the current required for the load. You have to make sure both voltages are the same. What are your experiences ? Better dynamics with some loss of fine level details ?