August 30, 201213 yr Figure on spending around $1000 US dollars for an economy build. If you want to add a fancy case and components, that amount could easily quadruple!
August 30, 201213 yr Mine was a little over 1500. Two box build with front panel express front and rear panels for both. Also I had a khozmo stepped attenuator and amb epsilon24 for power switching duties.
August 31, 201213 yr Negative Positive Bias before 5M resistor Just tested the PSU. yeah.. on the concrete.. because really can't find any room on the table. I followed Yun's BOM. I changed R5 R29 R15 R30 to 487K and kept R16 R6 at 20K, so the positive and negative should be 497V. The bias reading after the 5M resistor is 396V. I have no idea where the problem is. going to take a clear photo of the board and check to resistor values tomorrow.
August 31, 201213 yr The bias reading after the 5M resistor is 396V. That's normal. The meter is probably 10 megohm and pulling the voltage down. Unless you have a high voltage probe with a resistance of about 1 gigohm, you can't get a proper reading.
August 31, 201213 yr The BOM is for the 450V version so the voltage divider in the PSU has to be altered for 500V. There is detail of this elsewhere in the thread but nobody ever bothers to update the BOM. Most of the time we don't even bother with BOM's so there is that....
August 31, 201213 yr The meter is probably 10 megohm and pulling the voltage down. Unless you have a high voltage probe with a resistance of about 1 gigohm, you can't get a proper reading. Is this referring to all the readings? The BOM is for the 450V version so the voltage divider in the PSU has to be altered for 500V. There is detail of this elsewhere in the thread but nobody ever bothers to update the BOM. Most of the time we don't even bother with BOM's so there is that.... For V8 (Rev 0.6) ((R30+R15)/R16+1)*10 for negative ((R29+R5)/R6+1)*10 for positive right? I also swapped the zener string to 200V+200V+150V Edited August 31, 201213 yr by jwzhan
August 31, 201213 yr Is there a reason for the voltage readout to be ~100V lower after the RCRC filter? I still have not found a concrete answer to this question... Edited August 31, 201213 yr by ujamerstand
August 31, 201213 yr Just measured the zener diode and got 542V, and also measured the 10V reference between R6 and R5 which gave me 10.2V. Both should be with in tolerance. And the voltage divider are indeed the correct value (487K, 487K and 20K.) But the output are still only around 480V. Is there anymore test points that I should try? EDIT: photo added Edited August 31, 201213 yr by jwzhan
August 31, 201213 yr I may be wrong, but you need to forget about the bias circuit and concentrate on the rail voltages just after the filter caps (680uF) and at the output for the amps.
September 1, 201213 yr I may be wrong, but you need to forget about the bias circuit and concentrate on the rail voltages just after the filter caps (680uF) and at the output for the amps. yeah, I have, but I really can't find the reason for the strange rail voltage values. I have tested the zener string (which gave me 542V) and the 10V reference (which gave me 10.2V.) Any more recommended testing points and their values?
September 1, 201213 yr Have you triple checked your resistor values? I checked every resistor before I put them in, because I'm fairly paranoid. I can't get a correct value off the resistors because they are in circuit, but they do read 487K from the color bands, so I'd like to test a few more points before proceeding on pulling the resistors out if possible.
September 1, 201213 yr I think 475v and 476v isn't too bad especially when both sides are almost identical. It may be a bit off your intended 500v, but with lower voltage you get a slightly higher current which may not be a bad thing after all. I would rather leave it alone instead of ploughing through the boards desoldering the parts and messing things about. If the experts feel otherwise, please correct me.
September 1, 201213 yr Well first off, what are you seeing out of the transformer unregulated? The regulator needs a certain headroom to function correctly.
September 1, 201213 yr I think 475v and 476v isn't too bad especially when both sides are almost identical. It may be a bit off your intended 500v, but with lower voltage you get a slightly higher current which may not be a bad thing after all. I would rather leave it alone instead of ploughing through the boards desoldering the parts and messing things about. If the experts feel otherwise, please correct me. I wouldn't mind if that's what I set out to get, but it's not. I'm just afraid that something is horribly wrong. Well first off, what are you seeing out of the transformer unregulated? The regulator needs a certain headroom to function correctly. unloaded: 1 is 520V 2 is 50V 3 is 303V 4 is 170V loaded(measured from terminal blocks): 1 is 316V 2 is 294V 3 is 216V 4 is 284V measuring after the bridge just max out my meter.
September 1, 201213 yr I'm assuming you are measuring with respect to ground? For the output of the transformer you should measure across the winding, so the voltage across 1 and 2 and then 3 and 4.
September 1, 201213 yr I'm also a bit worried about the "maxing out my meter" comment as the cheap crap doesn't work at these voltages. They give the wrong data and the error range is huge.
September 1, 201213 yr I'm assuming you are measuring with respect to ground? For the output of the transformer you should measure across the winding, so the voltage across 1 and 2 and then 3 and 4. ah, didn't get that right. will remeasure them. I'm also a bit worried about the "maxing out my meter" comment as the cheap crap doesn't work at these voltages. They give the wrong data and the error range is huge. got a fluke 113 from lowes. negative rail starts at 500V and drops to 495V. something is wrong with the positive rail, only getting 30V from it, however, the 10V reference is still correct. massive headache now. not going to mess with it now... going to swap parts after the labor day. Edited September 1, 201213 yr by jwzhan
September 2, 201213 yr How come you don't have the CT connected to earth as per the schematic? unloaded: 1 is 520V 2 is 50V 3 is 303V 4 is 170V Are these readings measured as AC or DC? 1 & 2 should be one secondary winding. 3 & 4 should be another secondary winding. Corrected. Thanks, eggil Disconnected from the power supply, there should be no connection between these windings and any other in the transformer. Edited September 2, 201213 yr by wink
September 2, 201213 yr Fluke 113 is a quality meter. It should be able to measure these voltages with no problem
September 4, 201213 yr Thought I'd post my stuff here. Finally finished my kgsshv about a year late:) This is my first wading into electrostatic territory and I must say I am very impressed. Listening through 407s but will be rolling phones in the future. I can maybe post better impressions once I log some solid listening hours. Thanks to KG for putting out this sweet build. and thanks to all the stax mafia for being an awesome resource. here are some flickr pics. http://www.flickr.co...s/86619106@N06/
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