I received the board this Monday (May 4th) and I immediately connected it with a dual 9V transformer. It sounds smooth and has big sound stage. I left the DAC run for a few days continuously and it turns out to be better and better. Unluckily, when I unplugged it from the mains AC supply yesterday, I heard a loud "park lark" from the speaker and I know its not good at all. When I re-plugged it to the mains again, I recognize the locking LED is not lighted or blinking.
I measured the voltage of each point and found the 3.3V is only 2V. I checked the onboard regulator and noted the input is 8.5V while output is only 2V. I thought the regulator is dead therefore I replaced it with a new one. However, situation remains unchanged and I also discovered the original 3.3V regulator is working properly. Can anyone help me: -
1. How to trouble shoot this situation?
2. What could be wrong in this situation?
3. What are the parts in the board that needs this 3.3V supply? In the worst case, I can replace all active components after this 3.3V.
I measured the voltage of each point and found the 3.3V is only 2V. I checked the onboard regulator and noted the input is 8.5V while output is only 2V. I thought the regulator is dead therefore I replaced it with a new one. However, situation remains unchanged
and I also discovered the original 3.3V regulator is working properly. Can anyone help me: -1. How to trouble shoot this situation?
2. What could be wrong in this situation?
3. What are the parts in the board that needs this 3.3V supply? In the worst case, I can replace all active components after this 3.3V.
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"Unluckily, when I unplugged it from the mains AC supply yesterday, I heard a loud "park lark" from the speaker"
I would suspect the transformer and the bridge and the main reservoir cap i.e. everything before the regulator. Is the input supposed to be 12V?
Did it die the first time you switch it off?
I would suspect the transformer and the bridge and the main reservoir cap i.e. everything before the regulator. Is the input supposed to be 12V?
Did it die the first time you switch it off?
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I can't really help with troubleshooting, but can assure you that an ultraloud plop during switch off is normal with this design and no sign of a broken dam.
A 9 volts transformer is not recommended, it should be 7 or 8 volts ac but I do not think that the resulting dc voltage of a 9v transformer secondary can destroy the the dam. It might be stress for the 16v caps, but they should not die immediately.
A 9 volts transformer is not recommended, it should be 7 or 8 volts ac but I do not think that the resulting dc voltage of a 9v transformer secondary can destroy the the dam. It might be stress for the 16v caps, but they should not die immediately.
I had a number of plug and unplug before it died. Yet, everytime when I unplug it, a very slight noice came out from the speaker but the last time was a loud one. Since other voltages are correct; that are, those 1.2V, +ve and -ve rails, I don't think the bridge or the reservoir caps are gone.
The parts number of the ICs are too small for me to read. I tried with a manifiying glass but no hope. The most suspected component; in my opinion, is the MCU that I will replace it and have a try.
The parts number of the ICs are too small for me to read. I tried with a manifiying glass but no hope. The most suspected component; in my opinion, is the MCU that I will replace it and have a try.
Hi Ristar, my system is working normally with LP gears.
Hi Glt, I have not started to work on the board yet. I can only denote the MCU and FPGA while the printing marks on other IC chips are too small for an old man to read. Can you tell me the part numbers of isolators and where are they located on the board.
The current resistance on the 3.3V output to GND is 2.5 ohmes and input to GND is 3K that I will try to do the following in sequence:
1. Unplug the FPGA from its socket.
2. Lift the +ve rail of the MCU.
I will measure the resistance of 3.3V after removing each of the above. Can anyone help to give me the reading of the resistance on the output to GND and input to GND on the 3.3V regulator?
I wrote an email to Soekris last Friday and is looking forward for them to give me a clue on what could be happening but no reply yet.
Thanks
Hi Glt, I have not started to work on the board yet. I can only denote the MCU and FPGA while the printing marks on other IC chips are too small for an old man to read. Can you tell me the part numbers of isolators and where are they located on the board.
The current resistance on the 3.3V output to GND is 2.5 ohmes and input to GND is 3K that I will try to do the following in sequence:
1. Unplug the FPGA from its socket.
2. Lift the +ve rail of the MCU.
I will measure the resistance of 3.3V after removing each of the above. Can anyone help to give me the reading of the resistance on the output to GND and input to GND on the 3.3V regulator?
I wrote an email to Soekris last Friday and is looking forward for them to give me a clue on what could be happening but no reply yet.
Thanks
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Read Glt's blog: https://hifiduino.wordpress.com/2015/01/30/building-soekris-r-2r-dac/
Measure the pins on J2 [read the link above and see which of the LDOs you've killed] from memory, the 3.3v regulator never runs hot... but it's been awhile as I've also removed it from both my boards. Measure the voltage at the last 820uF cap also.
If the caps are dead there's no need to worry as it's easy to replace and you can take the opportunity to "upgrade" to polymer caps.
As long as the 5v; 4v; 1.2v references aren't dead the situation isn't difficult to fix, I think. Easy to just plug in another 3.3v source or LDO.
BTW, are you sharing the power supply with something else? The current draw reads like there is a short somewhere or something else is drawing power from your PSU.
Soekris R2R certified
Just an update to the R2R DAC after putting it aside for a few months until this week. I went to my friend's electronic factory in China and started working on the board by removing the isolators first. No change on the circuit reading - the ohme reading after the 3.3V is still zero. When I was figuring what to remove thereafter, a technician came around and asked me what is the problem and I told him the circuit after the 3.3V regulator is shorted. He said as a technican, he does not need the circuit and can find out which is the faulty part and I think it worths sharing with all of you here.
He connected the voltage rails after the 3.3V with a regulated voltage/current supply. When he turned on the supply, the current reached 1.34A instead of a few hundred mA. He left it on for a few seconds and showed me the SPARTAN-6 is getting very hot therefore he concluded that this is the faulty part. Although they have a FPGA dis-mounting machine, we did not de-solder it because firstly, the FPGA has program inside that I'm not able to access and replace. Secondly, it is very difficult to mount the FPGA on the board manually. Other than desoldering the SPATAN-6, I further desoldered other chips after the 3.3V (as shown in photo) that the supply rails remain shorted. In this respect, I can almost certain that the SPARTAN-6 is dead and I'm not able to fix it.
Will close this file unless anyone can suggest alternatives. Thank you for all of you who helped me in sorting this out.
Just an update to the R2R DAC after putting it aside for a few months until this week. I went to my friend's electronic factory in China and started working on the board by removing the isolators first. No change on the circuit reading - the ohme reading after the 3.3V is still zero. When I was figuring what to remove thereafter, a technician came around and asked me what is the problem and I told him the circuit after the 3.3V regulator is shorted. He said as a technican, he does not need the circuit and can find out which is the faulty part and I think it worths sharing with all of you here.
He connected the voltage rails after the 3.3V with a regulated voltage/current supply. When he turned on the supply, the current reached 1.34A instead of a few hundred mA. He left it on for a few seconds and showed me the SPARTAN-6 is getting very hot therefore he concluded that this is the faulty part. Although they have a FPGA dis-mounting machine, we did not de-solder it because firstly, the FPGA has program inside that I'm not able to access and replace. Secondly, it is very difficult to mount the FPGA on the board manually. Other than desoldering the SPATAN-6, I further desoldered other chips after the 3.3V (as shown in photo) that the supply rails remain shorted. In this respect, I can almost certain that the SPARTAN-6 is dead and I'm not able to fix it.
Will close this file unless anyone can suggest alternatives. Thank you for all of you who helped me in sorting this out.
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