DronEvil

Just got mine. Thanks so much for all your hard work on this!

Seriously, thanks so much for all your hard work on this, @sbelyo!

yep 2mm is cool with me.

@sbelyo what's your paypal address? Would like to send you payment today before I forget! Also curious if anyone has any good L-Bracket recommendations for BH/GG etc.? Thanks!

thanks so much for your work on this!

Awesome. I can upload the gerbers tonight when I get home if we want to add this to the sheet? Not 100% sure of the differences either. Does anyone know? Quick glance shows multiple heater connections Also curious if GRHV is the best PSU to use for this or if there is a different BH PSU that should be used? Gonna do some reading on the threads here tonight to try and find out.

Yes indeed. I have a few things in the work that these 4 will be for. Would anyone be interested in getting Grounded Grid or KGBH boards? I can provide gerbers. I'd like to get one or the other (or both) but if no one else is interested I'm not gonna rock the boat etc.

I think I may have figured it out. Looks like I had a a 2SC2240 where one of the 2SA970s should have been. I'm never gonna poke and then solder all at once ever again. Will be stuffing one component fully at a time moving forward as this was just me being a blind idiot and could have been completely avoided. Still need to troubleshoot why I can't get balance/offset down, but no more smoking parts is a step in the right direction. Sorry for causing all the noise in here! Currently i've got around -300vDC between +/O and i can't really get it to move at all while adjusting balance or offset. Bias sits pretty at 580vDC. -o is 100-120vDC and +o is 200-20vDC I'm getting almost exactly +/-15v & +/- 338v into the amp from the PSU, so i'm not sure what's going on quite yet. Is it possible that I broke/over-turned the trimmer pots while adjusting them too far in one direction when i had an incorrect part in the circuit?

For sure! I was just mentioning the value of the resistors because I don't think I can get exactly 50kohm parts with the heat and volt requirements, and wanted to make sure that it being ~49kohm is OK. I'm also now wondering if I actually need 51kohm based on the schematic below (R13 and R14) which I am now reviewing again. I'm thinking that I have a part installed wrong or a wrong part installed (rather than cold joint) since it is happening to both 50kohm resistors in both channels on both boards (which is why I was asking about the STN9360 vs the 2SA1486). When I look at the BOM, I'm not entirely sure what the color coding means. I'm wondering if since I'm using 2SC1815/2SC2440 and 2K170 (couldn't find LSK389 or either of the MPSWs) that I also need to be using 2SA1486 instead of STN9360? Based on the photos of other people's finished boards and the spec sheets of the concerned components, I wouldn't think so, but i'm not 100% positive. Best I can tell from the schematic my problem lies (i think) somewhere between Q2/3 and Q6/7. BOM https://docs.google.com/spreadsheets/d/14Tblo23t4EUpw9DmFts-9yiWPm0UxGmupoycTxLq7i4/edit#gid=0 kgst.PDF

So I installed these. http://www.bdent.com/2sc2240bl-toshiba-audio-transistor.html https://www.mouser.com/ProductDetail/Xicon/273-499K-RC/?qs=sGAEpiMZZMvD44QvxK4%2FiYpTv2fSXl6f I measured the resistor and they are 49.89kohms so hopefully that's good enough (can't find any 50-51k that are 1/2w and 700v). The issue still persists. I was able to get balance/offset to ~1v on one channel (after about an hour of power on) and then balance just randomly went to -500v on its own after being stable for about 20 minutes. The other channel i could get offset to ~3v but balance would never go below 30v. The resistors started getting brown again so I turned it off. Am I misunderstanding the BOM/board, and I shouldn't be using STN9360 and instead be using these 2SA1486? http://www.bdent.com/2sa1486-az-nec-switching-power-transistor.html

I actually am thinking that maybe i've got the wrong transistors in there. It is possible that the 2sc22s got mixed with my 2sk170s on my desk when i was stuffing. I don't have any more 2sc22s on hand, so gonna order a few more and then measure when they arrive. Thankfully I have a stash of the roasted resistors on hand (and they didn't explode, just got toasty, so I should be able to remove them without issue). This project has taught me that (i think) I need to stuff then solder a single component at a time (or group of same) rather than stuffing everything and then soldering. These estat amps are way more complicated than the simple amps i've built before, but I'm enjoying the work and learning. Will follow up in a couple days once my new 2sc2s arrive and I do some more troubleshooting.

Hi everyone, if I shouldn't be posting this here, please just let me know and I'll move it. I am new to ESTAT amps, but have built some stereo tube and SS amps in the past. I just finished building my first estat amp, a KGST, but am having some issues with the amp boards. PSU looks perfect. All DC outs are what I expect them to be (~350v and ~15v) and I have bias set to 580v. When I connected the PSU to my amp for the first time last night, I wasn't able to adjust balance/offset to any degree of success. I could get offset to around -5/+5v (but it would fluctuate) but balance was basically +50v or -500v, so I knew something was wrong. I turned it off after about an hour of trying to adjust balance/offset. This morning, after coffee, I noticed that I seemed to have roasted a resistor in the SAME place on both boards, so I'm thinking I've definitely done something wrong here. Pictures of where the resistor is are below, and I'm going through the schematic to see where that resistor is as well (as best I can working off the board and the schematic side by side). While I do that, does anyone have any advise for next troubleshooting steps? I've already gone over all my solder joints and the look fine. I also cleaned the boards with 99% isopropyl and a toothbrush after i finished soldering. I can post some more pics of the boards if you'd like to eyeball them? Thanks in advance for your guidance!

I'm interested in some GRLV and HV boards. Is it cool If I just add myself to that spreadsheet? This is my first GB on here so I just want to make sure i'm follow proper etiquette.

Hi everyone, I'm hoping you can sanity check these trafo specs for me before I pull the trigger on my order from Primrose Audio (SumR). I've read through this thread more than a few times to try and figure out exactly what I need for my megatron build. I'm using the v .2 meg boards and an older kgsshv psu board (the ones that have 2x 420-ct-420v and 1x 16-ct-16v inputs instead of the newer 2x 420/420 and 1x 15-15-ct). If you would like me to post pics of the board just let me know. I know this isn't optimal, but it's all I have to work with unfortunately. Thanks in advance for your input! MEGATRON POWER Power Rating 234VA Secondaries 2x 420VAC-0-420VAC @ 130mA 1x 16VAC-0-16VAC @ 500mA MEGATRON HEATER FILAMENTS (2x 6CA7 Tubes) Power Rating 51VA Secondaries 2x 6.3VAC @ 4A MEGATRON HEATER FILAMENTS (4x 6CA7 Tubes) Power Rating 101VA Secondaries 2x 6.3VAC @ 8A MEGATRON HEATER FILAMENTS (2x 12AX7 & 2x 12AU7 Tubes) Power Rating 10VA Secondary 1x 6.3VAC @ 1.3A

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