Hey all! Not much experience with DAC design, but got a question - I have a TDA1541 based DAC - all voltages appear to be per design. No output to OPAMPs...is it possible to have bad (fake) TDA1541 with all pin voltages correct?
DAC Input to CS8412, SAA7220 to TDA1541. LED lights for good Signal lock on TOSLINK and COAX Digital input. Just no output either channel
DAC Input to CS8412, SAA7220 to TDA1541. LED lights for good Signal lock on TOSLINK and COAX Digital input. Just no output either channel
I have read that the output of the CS8412 to the SAA7220 should have 1.7V if working properly...I am around 1.2v
Have you got a schematic and if so, can you post it and indicate precisely what you measured where? Maybe that will give someone a clue about what might be going on.
Are those LEDs driven by the CS8412?
Do you mean the serial data from the CS8412 to the SAA7220 (pin 26 of the CS8412 and pin 3 of the SAA7220, if I interpret its datasheet properly)? It's two's complement with 5 V high level, so I would expect an average voltage of 2.5 V when playing some sound, 0 V when playing absolute digital silence.
SAA7220 datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/view/19042/PHILIPS/SAA7220.html
CS8412 datasheet: http://www.dddac.de/files/CS8411_12.pdf
Are those LEDs driven by the CS8412?
Do you mean the serial data from the CS8412 to the SAA7220 (pin 26 of the CS8412 and pin 3 of the SAA7220, if I interpret its datasheet properly)? It's two's complement with 5 V high level, so I would expect an average voltage of 2.5 V when playing some sound, 0 V when playing absolute digital silence.
SAA7220 datasheet: https://pdf1.alldatasheet.com/datasheet-pdf/view/19042/PHILIPS/SAA7220.html
CS8412 datasheet: http://www.dddac.de/files/CS8411_12.pdf
Its one of those TDA1541 Kits you see all over the net...I do not have the formal Schematic...but will continue to search...The OPAMPS getting proper voltage, and the TDA1541 also has right voltages at pins too.
I used a Probe and speaker to trace analog out of TDA1541 / input to opamp...nothing there, so must be at SAA7220 or the CS8412
I used a Probe and speaker to trace analog out of TDA1541 / input to opamp...nothing there, so must be at SAA7220 or the CS8412
Attachments
![PXL_20211217_022826699[1].jpg](/community/data/attachments/913/913743-b714f29399f96c02ddd39f7c799ed6ab.jpg?hash=txTyk5n5bA)
The TDA1541 has a current output that is normally connected to the virtual ground input of a transimpedance amplifier (typically an op-amp with a resistor and a capacitor). Ideally (*) there shouldn't be any signal voltage at the op-amp input, only at the op-amp output. Is there any signal at the op-amp output?
(*): With a theoretical ideal op-amp there would be no signal voltage at all, with a real-life op-amp the signal voltage at the op-amp input will be very small indeed, typically 500 to 100 000 times smaller than the op-amp's output signal depending on the audio frequency.
(*): With a theoretical ideal op-amp there would be no signal voltage at all, with a real-life op-amp the signal voltage at the op-amp input will be very small indeed, typically 500 to 100 000 times smaller than the op-amp's output signal depending on the audio frequency.
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I have been using a a high efficiency Fostex 3" speaker hard wired to needle tipped multimeter probes.
When used, the sound is barely audible, but confirms a signal is present
When used, the sound is barely audible, but confirms a signal is present
Ha, just replaced the TDA1541 and she fired right up...I suspected the DAC chip...
I had this B&O 5500 CD player that I could never get working and pulled teh SAA7220 and the TDA1541 chip....both work fine....glad I never threw the B&O player away... anyone want it for free? Come get it!!!
I had this B&O 5500 CD player that I could never get working and pulled teh SAA7220 and the TDA1541 chip....both work fine....glad I never threw the B&O player away... anyone want it for free? Come get it!!!
The previous owner said it worked for a while, then stopped...Fake or bad chip is culprit...luckily I only spent about 2 hours on it...should have just swapped the chip from the get go. Not bad sounding DAC...