Just got done popuating the board using Dario's BOM and I'm only getting 1/2 sec of output and the amp goes into protection.
I've been checking voltages, impedences, and even swapped out the OPA827 on BD, and it checks good (sounds really good) on another dac board.
I've also check component orientation, all check good. Also checked voltages at the 3.3 and 5vdc regs and they seem good.
Here's a pic. What should I be checking? I do get the power led on, but no other leds.
Looks like the heatsink on that regulator is touching the other reg (shorting)
Transformer wiring looks a bit suspect also. Do you have a wiring diagram for the transformer?
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Looks like the heatsink on that regulator is touching the other reg (shorting)
Transformer wiring looks a bit suspect also. Do you have a wiring diagram for the transformer?
I know it looks like that, but it isn't, however, I removed the heatsink anyway just to verify that. The trafo has dual, 15vac secondaries, two greens, two blues. So, I've paralleled the secondaries. Maybe the colors are wrong???? I've tried runing a single secondary and it doesn't change anything. I've measured the secondaries, both paralleled and single at 15+ vac.
1. The negative regulator is showing an output of -12vdc, and the rail at the opamp is showing same voltage, so it's good.
2. The posivite reg is only producing +2.6vdc, and that is what the + rail is showing at the opamp, so clearly, there's a short.
3. I've removed the bridge rectifier and it checks good: it has a vout of 15+. So it's good.
I can't figure out what's wrong at this point and have pulled out plenty of hair over this.
I agree with you that there must be a short someplace, I just don't know what the problem is.
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Looks like the heatsink on that regulator is touching the other reg (shorting)
Transformer wiring looks a bit suspect also. Do you have a wiring diagram for the transformer?
I've attached the trafo pdf.
Thanks for looking at this.
I'm happy that you have a working DAC, now
Didn't told you to check transformer wiring?
Yes, and with the OPA827 on BD this thing sounds goooooood. Just getting ready to put in on a larger rig. The picture attached is an MTM that I built, veneered in 1/42 makore.
See, speaker building is my thing, not line level stuff. But, I'm learning.
That's a bdp-95 you see in the background. Let's compare them....
See, speaker building is my thing, not line level stuff. But, I'm learning.
That's a bdp-95 you see in the background. Let's compare them....
Attachments
Didn't tried yet AD797 but IMHO OPA827 is the best opamp I've heard so far.
Wow Greg!
Yours it's not the same 827, the one in BOM is OPA827 from TI/Burr-Brown which is a single...it's the successor of OPA627.
Thread is not mine...BTW very nice building
I realised my AD827 was not the same after i posted it, however I don't plan to be using an op amp in the future as I much prefer a discrete approach these days. I had great success with Giorgios (from TNT Audio) output stage on my TDA1541 DAC Just a matter of time before one of these is hanging off the end of this little gem.
hi guys.. i just bought this ak4396 kit off ebay (a little too late, i know)
i'm just wondering, how do we connect the transformer to the 13-15 supply voltage if we only have dual secondary transformer (judging by the 3 holes, i think it requires center tapped model)? can we just put the middle + & - wires together?
thanks in advance
i'm just wondering, how do we connect the transformer to the 13-15 supply voltage if we only have dual secondary transformer (judging by the 3 holes, i think it requires center tapped model)? can we just put the middle + & - wires together?
thanks in advance