jwzhan

For positive, I don't really know what fried the LT1021-10, because all the other parts are good. All I did was replacing the chip, and it started to work again. For negative, it's just common sense not being so common.... Cap's metal container got too close to the trace; silkscreen got blown away and there was a short via the container.. fixed with some kapton tape. There was actually another minor problem with the Bias.... Apparently testing on wooden floor with 8mm stand-off is not a good idea... Somehow it shorted via the floor and completely blew out one trace (the one that connects the bias to the input cap) and left a pretty big burn mark on the floor. Fixed with a jumper.. Hopefully this is the end of all explosions... I'll get some pics later. it ain't pretty though, considering what it has been through.

PSU is finally done.... positive is stable at 505V, negative at -505V, and bias at 396V. I didn't use the Fluke 113 due to the low impedance input, so the measurement might be off by one percent; however, as long as they are matching I'm satisfied. My friend made a LTspice file for the positive and negatic rail. If anyone is interested, just send me a PM with email.

Schematic is available. It can be easily checked by comparing. The trace error of the previous version is mentioned somewhere in this thread.. you probably should take your time and go through the thread even if you got the correct board. You can never be careful enough... even the slightest error can lead to violent explosion...

To my knowledge the V6 onboard version doesn't have trace error and is easier to build. The V7 offboard on the other hand has trace error, but it's fixed in the latest version (REV 0.5). From a prior post, there is a revised PSU, but there is no change in performance. I don't know about the size thing... offboard builds need one 3U400 or two 2U whereas the onboard can be tightly fitted into one 2U..

lesson learned note taken, just bought some kapton From a thread posted by KG on headfi, it's 5.5mA

I can't find anything wrong with the board. This is a pretty simple two sided board. For some reason it's just not working for me... the short that happened yesterday was just out of no where... it just decided to blow through the silkscreen of the board and to have a short...

stuffed every part back in for the Positive rail, replaced the reference today and fired it up. Everything worked for.... 20min. There was a violent explosion under the 680uF input cap of Negative rail (the arc also left a mark on the wima.) I pulled the cap out and, sure enough there was a short between the ground and the rail. basically it blew through the plastic cover of the cap and shorted via the metal container of the cap on the top (red) trace. this PSU is not being kind to me.... First it was a reference chip that got fried by nothing, and I had to take all the transistors out to confirm that. Then it's this... will i ever get it up and running...

±15V and Bias are working. -497V is giving me around -496V for now. but +497V is just plain wrong. The +497V measured +486V just before dramatically dropping to +30V. When it was still 30V, I measured the reference which is still at 10V. Then I left it there for the whole labor day weekend. When turning it back on, the output gave me 80V. Measuring before the lt1021 gave me 80V and measuring the reference voltage also gave me 80V, which means lt1021 is fried. so here are what I did today: pulled lt1021 out and I thought 10m90s, 2sa1486, and 2sc3840 are also fried so I pulled those out too, but they all measured fine (BJT with hfe and 10m90s with a simple testing circuit.) I then went on measuring the resistors, which are all within tolerance. I also pulled out the 100uF output caps which are again fine (pulled out so I can actually measure the resistor ladder.) I then measured the resistance between the GDS of the fqpf8n80c in circuit, which are consistant to the ones in the -500V. I also measured the bridge with diode test in circuit again, which are also consistant to the ones in the -500V. The rest of the diodes still conduct fine unidirectionally. Massive confusion and headache. probably going to put everything back and put a good lt1021 in there to see what happens...

ah, didn't get that right. will remeasure them. 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.

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. 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.

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.

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?

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

Is this referring to all the readings? 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

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.

Isn't the "balanced" setup the same as "unbalanced"? Can't find any other wiring schemes.... so... are all the "better" after market wired the same way and advertised as balanced? wait a second....

It's exact place where I got these, hence the purple color. Maybe mass ordering will result in cheaper pricing. drill/tap a blind hole on the faceplate, take out the nut, and screw the board/jack in there. or just screw the jack in there and solder the board onto the jack. I thought about labelling them, but didn't do it since stax pin-out is quite easy to find.

Just got 3 of these PCBs from the fabhouse. Dimension is roughly 1.7x1.7 inch. Cost is about $4 per board (free shipping.) perfect fit and very well made. If anyone is interested, I have the eagle file. I can probably convert it into gerber.

donated what I can at the moment. maybe more next month.

got me worried for sometime. I thought I would be stuck with the other sites. Thank you Todd, will gladly donate if possible.

Mine arrived too. Quality is definately top notch. Thank you Justin.

wasn't even a close match... IIRC it was 1-6 2-6 4-6. Murray obliterated him. Murray lost to Federer last month on the Wimbledon final. Well... it's seventy some years since the Brits won a major event in their own courts. I'm satisfied, because I like underdogs.

Curiosity just landed if NPR was right.

hmmmm premium. does he mean that he makes a premium for every piece of Shit he sells?

grid cable FTW