Pin 12 of saa chip...(so not on tda). This is also the closest gnd point...but it's just not working (as I said it's burning the rectifiers....)
I found different instrunctions but none worked: without grounding, wuth a resistor between xin-xout, with a cap btwn xin and ground.... Still don't understand why rectifiers on the module go hot when I try to connect ground....
Blowing fuses and hot rectifiers indicate a current draw that is very high, or a short. Either you are not connecting the board correctly or there is an issue with the board.
How are you powering and connecting the board? The ebay ad specifies 8 to 12 vac at 0.5A for power. I see that for output there is MCK and GND at the other end of the board.
How are you powering and connecting the board? The ebay ad specifies 8 to 12 vac at 0.5A for power. I see that for output there is MCK and GND at the other end of the board.
I took 10v AC from the cd player transformer. MCK is supposed to be the main freq so that one is feeding the saa chip on pin 11. About ground...you know the story. Now i'm trying with a separate transformer which provide 11v...still no luck. Could be that the txco component is broken ?
Did you remove all of the clock related components from pins 10 and 11? There are usually capacitors and resistors in addition to the crystal connected to pins 10 and 11 that need to be disconnected from the pins. If they are not disconnected from pin 11, they may provide a path to ground.
Of course all are gone. I did also a test to check cd player is still running so I placed the original quartz plus some spare components (caps and resistor) on a small pcb and then connect back to the board. All worked fine ...so the player is ok.
Well, I had to ask. Troubleshooting from afar is difficult with little information so questions need to be asked and answered in order to try to get a complete picture. Sort of like a doctor trying to diagnose an illness by asking questions.
It seems that there may be an issue with the clock board then.
It seems that there may be an issue with the clock board then.
Not a problem, I'm here to give any details (I'm the one who came to doctor). At Vcc pin of txco I measure 5v sharp. I isolated output from the 74hc...no luck. I must find an oscilloscope (those USB connected are of any good?)
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Some more thoughts:
- Do you have the schematic for your player to check the components that are connected to the clock input to confirm that you have removed all of them and placed on a circuit board?
- After removing the original clock components, what is the measured resistance between pin 11 and Gnd?
- On your new clock board, when powered up but not connected to the SA7220, what is the voltage between MCK and Gnd? If you connect a 2k to MCK and Gnd, what is the voltage? Do the diodes heat up in these situations?
- Connect a small value resistor (say 10 ohms) in series with MCK and pin 11 to check the current draw when the board is connected to the SAA7220. Since the diodes are heating up, power up and measure the voltage drop across the resistor and quickly turn off. Also what is the voltage between MCK (pin11) and Gnd? Only do this if you are confident that this will not permanently damage something but you have already powered it up previously and it still works with the original components back in place.
- I don't have any experience with usb/computer oscilloscopes.
- Do you have the schematic for your player to check the components that are connected to the clock input to confirm that you have removed all of them and placed on a circuit board?
- After removing the original clock components, what is the measured resistance between pin 11 and Gnd?
- On your new clock board, when powered up but not connected to the SA7220, what is the voltage between MCK and Gnd? If you connect a 2k to MCK and Gnd, what is the voltage? Do the diodes heat up in these situations?
- Connect a small value resistor (say 10 ohms) in series with MCK and pin 11 to check the current draw when the board is connected to the SAA7220. Since the diodes are heating up, power up and measure the voltage drop across the resistor and quickly turn off. Also what is the voltage between MCK (pin11) and Gnd? Only do this if you are confident that this will not permanently damage something but you have already powered it up previously and it still works with the original components back in place.
- I don't have any experience with usb/computer oscilloscopes.
I couldn't wait that long so here are the answers:
1. Yes, I have. I removed 2 caps, one resistor and of course quartz
2. 0(zero)
3. 0.7 v (I also measured mck/2 and mck/4 and the last two have 5v). With 2k2 resistor there is no measurable voltage and no heating diodes
4. Nothing measurable on a 12ohm res. 0.4v btw pin 11 and ground. I tend to say the txco is dead as there is no voltage on its output...
1. Yes, I have. I removed 2 caps, one resistor and of course quartz
2. 0(zero)
3. 0.7 v (I also measured mck/2 and mck/4 and the last two have 5v). With 2k2 resistor there is no measurable voltage and no heating diodes
4. Nothing measurable on a 12ohm res. 0.4v btw pin 11 and ground. I tend to say the txco is dead as there is no voltage on its output...
Zero resistance between pin 11 and ground does not seem right. That implies that any signal to pin 11 will go to ground instead of to the chip. This needs to be investigated.
So it seems that the new clock board is not outputting a signal. Maybe it got damaged by the short to ground at pin 11?
So it seems that the new clock board is not outputting a signal. Maybe it got damaged by the short to ground at pin 11?
Also if MCK/2 and /4 have output but MCK doesn't, then the issue is probably with the frequency divider ic.
Actually is not zero like in 'short' - I also have buzz function on my multimeter and there is no buzz if I put it btwn 11 and ground, more if I put the meter in short it still measure something...0.1 ohm . I also isolated the output of the tcxo bypassing the divider...still nothing. I'm more and more sure it is the tcxo module ��
You mentioned you took the 10V AC transformer winding. Did you try using a different/separate transformer as well? You could be creating a 5V DC voltage between the two grounds. Connecting those together will short some power supplies 🙂
You can get away with connecting the clock oscillator to the 10V AC winding that is used for the +5V on the main board. The transformer in a CD371 is center tapped with dual 20V and dual 10V windings.
Just measure the voltage between the two grounds and you will see 😉
Joris, I said it in a previous post: "
But I think it was too late and the TCXO was already fried ... 🙁
"
But I think it was too late and the TCXO was already fried ... 🙁
Has anybody tried the USB to simultaneous boards Audial are selling? Can I expect a big sound improvement from changing my WaveIO to Audial on my DIY Red Baron 1541a dac?