Are the CAL knobs in the correct position? If I remember well, you have to turn them all the way to the left until you feel that there is a switch switching, otherwise you get the right waveform, but at arbitrary scales.
There are also a couple of things in the circuit that could cause an oscillation at a too high frequency, but I have to start up a computer and serve a cat before I can get back to you about those.
There are also a couple of things in the circuit that could cause an oscillation at a too high frequency, but I have to start up a computer and serve a cat before I can get back to you about those.
What does the signal at R124 look like when you measure DC coupled with a 1:10 probe? How is the waveform positioned with respect to 0 V?
Does R124 make contact with J5 pin 47?
Edit: I just checked my own Verilog code and the voltage across R129 can't have anything to do with it.
Does R124 make contact with J5 pin 47?
Edit: I just checked my own Verilog code and the voltage across R129 can't have anything to do with it.
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See attached waverform with 1:10 probe but AC coupled (could get no sweep when DC coupled - was not triggering). Looks like 4Vpp. Also looks more 'square'. Am not sure what is happening with the x1 probe showing circa 1Vpp and the x10 probe 4Vpp...is it simply resolution?
Not sure exactly what you mean "waveform positioned with respect to 0V, but I measured the same locations as the scope probes (between R124 and R52 and got 265Vdc.
R129 with 85A3 ignited is 3.328Vdc drop.
R125 makes contact with J5.47 pad, but the pin contact is sketchy. I'll reflow it now.
Not sure exactly what you mean "waveform positioned with respect to 0V, but I measured the same locations as the scope probes (between R124 and R52 and got 265Vdc.
R129 with 85A3 ignited is 3.328Vdc drop.
R125 makes contact with J5.47 pad, but the pin contact is sketchy. I'll reflow it now.
Attachments
I was wondering why the clock signal was so small, it can't be due to the scope with a 50 MHz scope bandwidth. It's probably the big capacitive load from the 1:1 probe that caused it. The signal you get with a 1:10 probe looks fine. By the way, R52 is at -300 V rather than ground.
All in all, you have a good looking clock signal at R124 and the ignited85A2 signal (voltage across R129) is also fine. I'm curious to read what will happen when you have resoldered J5 pin 47.
All in all, you have a good looking clock signal at R124 and the ignited85A2 signal (voltage across R129) is also fine. I'm curious to read what will happen when you have resoldered J5 pin 47.
So you have a good-looking clock signal at R124, checked and resoldered the clock connection to the FPGA module and still the FPGA refuses to make net "relay" high or to release the reset of the sigma-delta modulator, which it should normally do a few seconds after detecting a good 27 MHz clock... I have to think about this one.
Just spent a few hours continuity checking all 160 pins on the FGPA sockets and have found nothing. Only thing not expected was that pins J5.13/15/17/19 all seem 'connected' somewhere, but not at J5 itself. A couple further down that line were also connected, but I did not take their numbers, possibly some or all of J5.57/75/67 etc.. Can verify this is you think it is worrisome Marcel.
Still no relay sounds...
Still no relay sounds...
Are you measuring from inside the FPGA connector to the destination? I found that measuring the solder leg was misleading, because the DMM probe would push the solder leg into the pad, so it looked as though the connection was good. Checking from inside the actual plug showed that the connections were actually bad
Have not been checking for adjacent pin shorts specifically, but have been making sure the correct FPGA pin has contact to the right 'other' pin.
Could the problem be something to do with the switches? I am not populating the 'Surprise' mode.
SW5 is not populated (left open)
SW4 is not populated and is shorted to 'loud'
SW3 has four positions one of which is engaged but I am still using the P9 I2S input which should override this (no 5 position switch here yet). Tried quite early in the process to unplug SW3 but have not done it lately, perhaps I should.
SW2 has three positions with 'surprise' not connected to the switch
SW1 has three positions with 'surprise' not connected to the switch
Could the problem be something to do with the switches? I am not populating the 'Surprise' mode.
SW5 is not populated (left open)
SW4 is not populated and is shorted to 'loud'
SW3 has four positions one of which is engaged but I am still using the P9 I2S input which should override this (no 5 position switch here yet). Tried quite early in the process to unplug SW3 but have not done it lately, perhaps I should.
SW2 has three positions with 'surprise' not connected to the switch
SW1 has three positions with 'surprise' not connected to the switch