Victor Chew Posted September 14, 2012 Report Share Posted September 14, 2012 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. Congrats! What was or were the earlier problem? Can you post pictures? This is where many would like to know what the potantial problem(s) is/are so that we can keep them in mind when doing our future builds. Grateful if you can share. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted September 14, 2012 Author Report Share Posted September 14, 2012 please post the ltspice model for all to see. i can host it if necessary. Quote Link to comment Share on other sites More sharing options...
jwzhan Posted September 14, 2012 Report Share Posted September 14, 2012 (edited) Congrats! What was or were the earlier problem? Can you post pictures? This is where many would like to know what the potantial problem(s) is/are so that we can keep them in mind when doing our future builds. Grateful if you can share. 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. Edited September 14, 2012 by jwzhan Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted September 14, 2012 Author Report Share Posted September 14, 2012 http://gilmore.chem.northwestern.edu/kgsshvpsu.asc Quote Link to comment Share on other sites More sharing options...
Victor Chew Posted September 14, 2012 Report Share Posted September 14, 2012 Any suggestions on how to check if the LT1021 is real and if it is, whether it is working to spec.before plugging it and letting charred parts tell us that it is bad? Quote Link to comment Share on other sites More sharing options...
jwzhan Posted September 14, 2012 Report Share Posted September 14, 2012 shove anything under 40V DC into the input and see if the output is 10V... pinout is in the datasheet. In my case, I just used a 19V laptop power supply.. Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted September 15, 2012 Report Share Posted September 15, 2012 Any suggestions on how to check if the LT1021 is real and if it is, whether it is working to spec.before plugging it and letting charred parts tell us that it is bad? 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. From my understanding a fried LT1021 was replaced, the positive rail then functioned correctly, the defective LT1021 did not damage any other parts. The negative rail shorted from an arc between the metal case of a cap and trace. I’m sure this is the second time I’ve seen the LT1021 give a builder good headache. Congrats on psu jwzhan! Quote Link to comment Share on other sites More sharing options...
eggil Posted September 15, 2012 Report Share Posted September 15, 2012 I am on a ship somewhere of the coast of Alaska using a very expensive internet connection, yet can't help myself but wasting valuable minutes following jwzhan's saga Quote Link to comment Share on other sites More sharing options...
jwzhan Posted September 15, 2012 Report Share Posted September 15, 2012 (edited) From my understanding a fried LT1021 was replaced, the positive rail then functioned correctly, the defective LT1021 did not damage any other parts. The negative rail shorted from an arc between the metal case of a cap and trace. yep, that's the gist of it. It seems that the LT1021 was not completely fried(open). It somehow acted like a diode with a strange breakdown voltage value that prevented the frying of every component. I got lucky on this one. I am on a ship somewhere of the coast of Alaska using a very expensive internet connection, yet can't help myself but wasting valuable minutes following jwzhan's saga You are making me feel bad. Now here is the photo that I promised haven't gotten a chance to do a proper cleaning. Everything that happened is quite visible. This is a very educational experience. Edited September 15, 2012 by jwzhan Quote Link to comment Share on other sites More sharing options...
Victor Chew Posted September 17, 2012 Report Share Posted September 17, 2012 (edited) I am on a ship somewhere of the coast of Alaska using a very expensive internet connection, yet can't help myself but wasting valuable minutes following jwzhan's saga True love is forever, in heart and in soul. Enjoy your trip our friend. Jwzhan, your perseverance has paid off although earlier on you had doubts as to whether you could get this PSU to function. Keep us posted of the balance of your journey. Edited September 17, 2012 by Victor Chew Quote Link to comment Share on other sites More sharing options...
gustavo.skn Posted September 17, 2012 Report Share Posted September 17, 2012 I did some research on parts that I need to buy since there are tons of BOMs, and looking at the schematics and the jpg and found that the resistor before the Pro Bias in pdf uses 5M and in jpg 4.7M... Which one is the right one? Or this don't make any difference? Should I trust more in the pdf schematic or the jpg? JPG: http://gilmore.chem.northwestern.edu/kgsshvps8e.jpg PDF: http://gilmore.chem.northwestern.edu/kgsshvps8e.pdf I'm going to build IXYS since A1968 is unobtainable nowadays... using IXYS, If I'm using a 450v supply, R6 and R16 stay as 20k right? The resistance on these is dependent only of the supply and not if it's ixys or a1968, is it correct? Thanks for your help Quote Link to comment Share on other sites More sharing options...
livewire Posted September 17, 2012 Report Share Posted September 17, 2012 I did some research on parts that I need to buy since there are tons of BOMs, and looking at the schematics and the jpg and found that the resistor before the Pro Bias in pdf uses 5M and in jpg 4.7M... Which one is the right one? Or this don't make any difference? Should I trust more in the pdf schematic or the jpg? no diff JPG: http://gilmore.chem..../kgsshvps8e.jpg PDF: http://gilmore.chem..../kgsshvps8e.pdf I'm going to build IXYS since A1968 is unobtainable nowadays... using IXYS, If I'm using a 450v supply, R6 and R16 stay as 20k right? The resistance on these is dependent only of the supply and not if it's ixys or a1968, is it correct? Thanks for your help yes Quote Link to comment Share on other sites More sharing options...
spritzer Posted September 17, 2012 Report Share Posted September 17, 2012 4M7 or 5M, it doesn't matter but do use one which is rated for 600V. Quote Link to comment Share on other sites More sharing options...
gustavo.skn Posted September 17, 2012 Report Share Posted September 17, 2012 yes Thanks livewire 4M7 or 5M, it doesn't matter but do use one which is rated for 600V. I was using the Lil Knight BOM and the 4.7M listed is the 293-4.7M-RC (xicon) which is rated only 350v... The KOA Speer, although listed as 700v voltage rating at mouser, if you look at the data sheet, the absolute maximum working voltage is only 350v too. The best I could get was the CMF-60 from Vishay/Dale, absolute maximum working voltage of 500v. Do you have any model that is rated at 600v spritzer? Looked at mouser and couldn't find any that kept the 50ppm/C and 1/2watt power rating Thanks Quote Link to comment Share on other sites More sharing options...
livewire Posted September 17, 2012 Report Share Posted September 17, 2012 The 500 volt CMF-60 is fine. Quote Link to comment Share on other sites More sharing options...
SoupRKnowva Posted September 17, 2012 Report Share Posted September 17, 2012 Thanks livewire I was using the Lil Knight BOM and the 4.7M listed is the 293-4.7M-RC (xicon) which is rated only 350v... The KOA Speer, although listed as 700v voltage rating at mouser, if you look at the data sheet, the absolute maximum working voltage is only 350v too. The best I could get was the CMF-60 from Vishay/Dale, absolute maximum working voltage of 500v. Do you have any model that is rated at 600v spritzer? Looked at mouser and couldn't find any that kept the 50ppm/C and 1/2watt power rating Thanks why not use something like this http://www.mouser.com/ProductDetail/Vishay/VR37000004704JR500/?qs=%2fha2pyFaduiU7nw9S7xDMMvHHBNPX2%252b3%2fjJQVocKE2r89FMTyeG1R5W5Hn7RFMSD thats what i ordered. Though i guess it doesnt have the tolerance of the units you're looking at, but its not like you're matching it to anything, so thats not really of the utmost importance Quote Link to comment Share on other sites More sharing options...
spritzer Posted September 17, 2012 Report Share Posted September 17, 2012 594-VR37000004704JR5 is a good one and what I use. Tolerance doesn't matter with this stuff. Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted September 17, 2012 Report Share Posted September 17, 2012 I was using the Lil Knight BOM No discredit towards Lil Knight, but this BOM thanks to ujamerstand is my preference. Quote Link to comment Share on other sites More sharing options...
jwzhan Posted September 18, 2012 Report Share Posted September 18, 2012 ^I also used Yun's BOM. It is one of the most informative BOMs out there. The resistor ladder equation is fixed, so everything in there is correct and is laid out in its simplest form. Although I've said it many times, thank you Yun. Quote Link to comment Share on other sites More sharing options...
ujamerstand Posted September 18, 2012 Report Share Posted September 18, 2012 It brightens my day to hear that. Cheers guys. That BOM is for the offboard sink version mainly though, so people building the onboard sink will need to modify it to suit. Quote Link to comment Share on other sites More sharing options...
gustavo.skn Posted September 18, 2012 Report Share Posted September 18, 2012 No discredit towards Lil Knight, but this BOM thanks to ujamerstand is my preference. It brightens my day to hear that. Cheers guys. That BOM is for the offboard sink version mainly though, so people building the onboard sink will need to modify it to suit. Thanks guys for this, It's going to be really helpful! Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted September 26, 2012 Report Share Posted September 26, 2012 If you have lots of heatsinking you can increase the third stage current. Which increases the high end frequency response a bit. Its the output stage current you want to bump up. You can bump up the 3rd stage a bit, but no reason to go crazy on that one. Kevin, what value did you have in mind when you said “You can bump up the 3rd stage a bit”? ... in my case I have Modushop 3U 400mm sinking with the output current stage targeted for 10mA with A1968’s parts. If you have a formula for the 3 stage source resistors that would be helpful. Quote Link to comment Share on other sites More sharing options...
justin Posted September 28, 2012 Report Share Posted September 28, 2012 (edited) if anyone's buying the PEEK plastic screws for this amp or the T2, i found a site with better pricing - www.solidspot.com Edited September 28, 2012 by justin Quote Link to comment Share on other sites More sharing options...
jwzhan Posted September 28, 2012 Report Share Posted September 28, 2012 ^where I got mine. Shipping was fast for me, but the company is in the same state as I, so I don't know about other states. My amp boards are up (somewhat,) now I'm just waiting for the case to come back from Cam-Expert, which might take a week or two. At the first start-up, I think I saw some white somke from one amp board, but there weren't any during the second, third and many after (they are all very short though, around 1 mintues or so, because the only heatsink the transistors have are the angled aluminum bars.) Will do more extensive testing after the panels and heatsinks come back. Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted October 2, 2012 Report Share Posted October 2, 2012 Bump for post #2022 Kevin or Birgir I would appreciate some guidance with this, my understanding of the circuit is dreadful at best, your knowledge would be most appreciated. Regards, John Quote Link to comment Share on other sites More sharing options...
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