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By way of introduction, I received my electronics training in 1964 and have hardly used it since. I have built a couple of relatively easy audio kits and I have a soldering station, solder sucker, multimeter, and basic tools.
I plan to build a BIIISE with all components (IVYIII) from TP except the DIYINHK XMOS DSD DXD 384kHz USB to I2S. I am trying to keep it as simple as possible.
I have a friend who will help me with the build but I'll also ask some questions here. I may ask questions to which the answer may seem self-evident, but I'd rather ask than have to fix later. I probably don't have the ability to troubleshoot.
Now, before I start soldering and I have a couple of things to question/confirm.
What is purpose of replacement 220ohm resistor for R8 provided with Placid? (2 with BP)
I want to confirm that in First Steps/Assembly of Placid "Adjust VR1...400R - 500R." means 400-500 ohms.
Also, three PNP bipolar transistors are marked QP3- QP5. Same for the three QN3 - QN5. I am assuming the third transistor should be QP4 and QN4 respectively.
I appreciate your help.
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Quote:What is purpose of replacement 220ohm resistor for R8 provided with Placid? (2 with BP) It is to strengthen the bootstrap Quote:I want to confirm that in First Steps/Assembly of Placid "Adjust VR1...400R - 500R." means 400-500 ohms. Yes Quote:Also, three PNP bipolar transistors are marked QP3- QP5. Same for the three QN3 - QN5. I am assuming the third transistor should be QP4 and QN4 respectively. No. On the positive half, there are two TO-220F NPNs (QN1, QN2) and three TO-92 PNPs (QP3-QP5). This opposite on the negative half.
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Rank: Member
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Quote:It is to strengthen the bootstrap I'm sorry but I don't know what this means. Am I correct in assuming that for my basic BIIISE build I just use the 470ohm R8 rather than the 220ohm replacement? Quote:Also, three PNP bipolar transistors are marked QP3- QP5. Same for the three QN3 - QN5. I am assuming the third transistor should be QP4 and QN4 respectively. I'm sorry, I did not understand that (QP3-QP5) means QP3, QP4, QP5. My mistake.
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Originally Posted by: Brian Donegan  Thanks Brian. I just realized what replacement means. I will go ahead and use the 220R. I'll also read the link you provided. Thank you.
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I just started soldering and at this point I am very cautious.
On the Placid (not BP) the marking on the PCB for C5 has an asterisk as "C5A*" The asterisk does not appear on the BP PCB. Is there a significance to this asterisk?
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No - it is there because in some cases that cap is not required. But in all cases it is more advisable to use it - because it makes the error amp unconditionally stable.
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Thanks Russ....back to soldering.
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Just a couple of quick questions: Is it correct that transistors QN1, QN2 are mounted in the center hole of the 2.5" heatsinks? Is C1A to be mounted flush with the PCB? Thank you. Edited by user Monday, January 19, 2015 9:22:14 PM(UTC)
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On the power transistors you will notice when you mount the heatsinks there is a position that will allow easy soldering and natural mounting to the PCB.
BTW people generally do not solder the heatsinks to the PCB - it makes it easier not to do so.
All parts can be flush to the PCB - but it is preferable for the power resistors R1 and R2 to elevate them off the PCB slightly for better air flow.
Cheers!
Russ
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I have completed the build of the Placid HD, Placid HD BP, BIIISE DAC and IVY III and its time to start setting up the transformers with the Placids as recommended in the guides. In addition to the recommended setup, a friend suggest that I run the Placids into a dummy load for final testing and setup before hooking up to the BIIISE/IVYIII. This sounds like a good idea to me. PLACID HD: (initial, no-load setup would be 5.25 volts and 490mA CCS) I calculated resistance in ohms is equal to the voltage in volts divided by the current in amps: 11.93 ohms = 5.25 volts/0.440 amps. Using a 12 ohm (10 watt) resistor as dummy load would require adjusting for a CCS of 487mA (437mA load + 50mA shunt). PLACID HD BP: (initial no-load setup would be 15 volts and 200mA CCS) The load would be connected separately with one load for each rail (one from + to gnd and one from - to gnd.) Calculating the load results in 100 ohms resistance = 15 volts/0.15mA. Using a 100 ohm (10 watt) resistor for each rail would require adjusting each rail for 200mA CCS (150mA load + 50mA shunt). Of course, I will be checking all setting again under load with BIIISE and IvyIII connected, warmed up, and playing audio. Will these resistors provide a load similar to the BIIISE/IvyIII? Is there any down side to doing this? Also, is there a specific way to mount the Mute & Lock LEDs on the BIIISE. I noticed one of the legs is longer than the other. Edited by user Tuesday, February 17, 2015 7:57:11 PM(UTC)
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Your initial settings are fine. When you actually connect the rig do fine tune the shunt current. When adjusting don't use the CSS as target. Better to use TP_shunt to aim for aprox. 50mA (I'm running mine at 100mA but that's just me) The legs of the LED's are meant to be cut. The uneven length is an indication of polarity:  You can mount them flush to the PCB like this or you can extend the legs with wires and mount the LEDs into the faceplate. Edited by user Wednesday, February 18, 2015 9:55:31 AM(UTC)
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Thank you AVR300.
I appreciate your assistance.
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My recent BIIISE, IVYIII, Placid HD, Placid HD BP build requires a CCS of 643 on the Placid HD to achieve a shunt current of 50mA at 5.27 volts. Is this acceptable? All the LEDs on the Tridents and the newest AVCC module are brightly lit.
After completing the builds I set the HD and HD BP at suggested no load settings with no trouble.
I connected the HD to the BIIISE and the HD BP to the Ivy (no signal inputs) and turned on the power. The readings on both channels of the HD BP were OK at 14.77 volts, 217 mA CCS, and 102mA shunt current, and 14.76 volts, 219 mA CCS and 105 mA shunt current. I will tune these later.
The HD, however, was more difficult.
Initial no load settings were 5.25 volts, 500mA CCS, and 292 shunt current. When connected to the BIIISE, I got 4.50 volts, 500mA CCS, and no shunt current. I was unable to adjust any of these with either VR1 or VR2. The LEDs on the Tridents were bright but the LED on the AVCC module was very dim.
After a little experimentation, I set the Placid HD no-load at: CCS 700, voltage 5.26volts, shunt = 686.
I connected the BIIISE and got CCS 702, 5.26volts, shunt = 113. The LED on the AVCC was now bright.
I decreased CCS to 643 bringing shunt down to 50 with voltage at 5.27. LED on AVCC still bright
This appears to be the best I can do powered with no signals being processed. Is this OK? I checked the components on the Tridents, AVCC and DAC but none were warm.
If this is acceptable, I plan to install an DIYINHK USB to I2S converter, power everything, start playing music and make "final" adjustments.
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Originally Posted by: Brian Donegan All seems normal to me.
Thank you. I'm getting a little excited. Now to add the USB to I2S.
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