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DIY TDA1541A PCB "D3"

Would you like a through hole version of the D3?

  • Yes

    Votes: 12 52.2%

  • Maybe, depends on the performance

    Votes: 11 47.8%
  • Total voters
    23
  • Poll closed .
Jump to Latest
#381
markos4553 said:
Hi Ben,


With a 150ohm resistor in place for R35&36:


AOR1= TR1 full CW 202.7mV
AOR1= TR1 full CCW 93.1mV


AOL1= TR2 full CW -85.3mV
AOL1= TR2 full CCW -200.2mV


I didn't write down the voltages earlier with the IV resistors out and the values were nearer to 500 ohm on the high end and 400 on the low end.


Thanks,


Mark K.
Click to expand...


Hi Mark,

You can do a couple of checks.

With the TDA out of the board, measure the voltage from the input leg of the trim pot (the leg that is not connected to the wiper) to ground. That should be 5V.

The next check would be to take out the 2K resistor (R32, R33) and with the TDA1541A in place, measure the voltage across the 150R IV resistor. The voltage should be .002A x 150R = 0.3V. The dac chip with no signal input/output should have a .002A current out.

If both are OK, then check the trim pot and R32 and R33 to make sure that their resistances are correct.

Ben
 
#382
markos4553 said:
Here it is now. Waiting on a cheap SPDIF to I2S converter.


Mark K.
Click to expand...

Mark,

Maybe also R30, just check that MELF is soldered to the pad.

Keep going! Your build looks pretty good!

InkedD3 powered3 - - Copy (1)_LI.jpg

Cheers,

Greg
 
#384
Ben Mah said:
Hi Mark,

You can do a couple of checks.

With the TDA out of the board, measure the voltage from the input leg of the trim pot (the leg that is not connected to the wiper) to ground. That should be 5V.

The next check would be to take out the 2K resistor (R32, R33) and with the TDA1541A in place, measure the voltage across the 150R IV resistor. The voltage should be .002A x 150R = 0.3V. The dac chip with no signal input/output should have a .002A current out.

If both are OK, then check the trim pot and R32 and R33 to make sure that their resistances are correct.

Ben
Click to expand...


Thanks Ben,


With the TDA out all three legs of TR1 and TR2 show 5 volts.


With the TDA in and 2K resistors out I am getting approx 300mV across the IV resistors.


R32 and R33 test good. ~1.999Kohms.


Back together and after reflowing some spots I'm getting AOL to work but not AOR.


Thanks,


Mark K.
 
#388
markos4553 said:
Sorry this has happened to you.🙁 Maybe it will still be usable. I bought extras of everything but C6, C14, C20 so I can remove and replace if necessary.



This is definitely difficult stuff. I can't wait to hear this thing though.


Thanks again,


Mark K.
Click to expand...

Mark,

The chip was warm but not hot. So, maybe.....

Yeah, I’m just waiting for parts to get here tomorrow. Otherwise, I will just start over.....or just have Ryan populate a board for me, last resort....

Glad you are making progress.

Cheers,

Greg
 
#390
markos4553 said:
Thanks Ben,


With the TDA out all three legs of TR1 and TR2 show 5 volts.


With the TDA in and 2K resistors out I am getting approx 300mV across the IV resistors.


R32 and R33 test good. ~1.999Kohms.


Back together and after reflowing some spots I'm getting AOL to work but not AOR.


Thanks,


Mark K.
Click to expand...

Hi Mark,

It looks like your are getting 5V as you should and the TDA chip is outputting 2mA as it should. That is good. So AOR not working is likely due to bad solder joint in the area of the pot, 2K resistor, and C56.

When you say AOR is not working, what did you do and what result did you get? It's hard to trouble shoot without information.

Ben
 
#391
Hi Ben,


I really appreciate the help!


On startup Both AOR and AOL vary a bit with AOL after a little while able to be zeroed and adjusted back and forth over the 0V point. AOR settles around 90mV with one TDA and 40mV with a different known working TDA.


I realize this is very difficult to troubleshoot over the internet and I can take any measurement if needed. I can also start desoldering and replacing if necessary.


Thanks,


Mark K.
 
#396
Hi Mark,

The Output bias circuit is very simple with only a few parts. If 5V is being delivered and the TDA chip is outputting 2mA, then something in the circuit is not working properly. It could be solder connections, or pot not working properly, or C56 not working properly.

You have already checked the 2K resistor. You also had measured 0.3V across the IV resistor when the 2K resistor was out of the circuit so the IV resistor and parallel capacitor are OK, and the TDA chip is sending out the 2mA current.

You can desolder the pot and test it out of circuit. You can desolder C56 and try the circuit without it. The circuit will work without the C56. Or if you have a capacitor tester, you can test it when you have the pot off the board.

Also check the solder joints again.

Ben
 
#397
I desoldered C56 and it checked out at 1uf and I've desoldered and checked TR1 and it checks out at 1K.


I've desoldered and replaced C58 even though it tested good at 154pF. I've now tested everything in the Bias circuit so it must be somewhere else.


Mark K.
 
#400
Well, it could be that the pot is hard to adjust. 90mV amounts to .090V/150R = .0006A and 40mV amounts to .040V/150R = .000267A.

When you adjust the pot, does the voltage across the IV resistor change from negative to positive or vice versa?
 
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