insanity
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Posts posted by insanity
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Thanks guys.
@livewire I made the knobs myself. Quite some time ago I sold a few pieces here. They are made from a piece of amboyna burl, mother of pearl inlay, PUR boats lacquer.
As usual I would not simply call one better than the other.
For the SR007mk3 I clearly prefer the carbon, for the 009 definitely the kgst. The conventional kgsshv is a little behind I believe, but also more suitable to the 007 than the 009.
From a perspective of build complexity, build beauty and aesthetics the carbon rules them all. The kgst is a rather simple build but compared to that is superb. The carbon with separate GRLV, offboard sinks is a different beast.
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Finally the holy triple with the frontplate of the carbon
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Well done. Happy for you that everything worked out in the end.
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The cascode current source can be set with an LV source.
Connect positive voltage to B+ terminal of the amp board. Connect negative voltage to the end of the 100ohm resistor adjacent to the DN2540 away from the heatsink. Measure voltage between the testpoints. Adjust until measurement is 1V for 20mA. (Calculation is 50ohms / 0.02A = 1V).
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Not quite true for me
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Thanks that is a very interesting fact to know. Do you have a dust free clean room to do your work or how do you prevent dust from entering the drivers?
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On 8/22/2016 at 4:37 PM, chinsettawong said:
Whatever your driver problem is, I might be able to help you.
Just out of curiosity. I know you build your own headphones, but what do you do with stax headphones with an imbalance?
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Wonderful build. What are the red pads under the caps?
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I have mine repaired and back up and running.
Again I am impressed of its sound compared to the conventional kgsshv.
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Looks like the voltage on the psu +400 drops to 60 when I put on the amp board. I will have to test if the same happens with the other amp board.
Will do it tomorrow. Too tired to work on HV.
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I am in the process of repairing by carbon. I now have the problem, that the offset seems to be stuck at -60V and I cannot adjust it in either direction.
I have checked the current sources and they work fine. Where would you start looking?
Of course the servo jumper is not connected.
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Red: soldering pad
Green: Traces
Blue: Suggestion for kapton tape, although depicted otherwise, I would not put it over the red pad. Just over the green trace.
Yellow arrows: Metal of the terminalblock coming very close to the green trace.
FYI: I used the terminal without the additional test point, but the crucial construction point is identical to the blue prints below.
I think the problem was that the solder/flux ran along the bent pin of the terminal block coming very close to the green trace. I think one or two layers of kapton should work because it slightly lifts the terminal block form the board and provides addition insulation between the bend pin and the trace. If place correctly, I think its very unlikely that either solder or flux would go under the kapton tape.
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Ok I agree that if you don't have flux under the terminal block, it will probably not be an issue. Nevertheless, terminal blocks take a bit more solder to fill the holes compared to other components.
To conclude: I think the boards are fine to use, as long as you are very careful about the soldering of the blocks. Furthermore, the ORIENTATION of the terminal block is curcial for the problem to appear. If you mount on the reverse side, there will be no problem. If you mount on the regular side, it may also matter where the openings of the terminal blocks point to (although there are traces running on both sides of the terminal blocks). In my project, the holes were pointing to the c2ms.
One could also just put some insulating material over both traces, be it kapton tape or something else that is non conductive.
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those are the boards from the last group buy. i dont think these are bad quality.
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there was also some flux, yes. Being it my soldering or not, since its not possible to check after soldering the terminal if there are any residues, it is unwise to continue building with this risk.
Concerning better teminal blocks. I have done an extensive search for more suitable terminal blocks. As we already know, there are none rated more than 400V with a pitch of 5mm.
During the search I found a lot of terminal blocks like this:
They are usually only rated 250V oder 300V. Would you risk using those? Sofar the only other options seems to solder the cables directly to the board, but that is very unpractical.
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Took a picture for you ;-)
This is no coincidence. And I cannot clean it off.
On the broken board, I plan to bridge the trace with a wire and put some kapton tape below the terminal blocks.
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During the repair process of my carbon I also checked on the other channel how it looks under the terminal block. There was no short, but it looked like it would have failed as well within some time.
I must therefore recommend for everyone using the v0.5 boards not to use such terminal blocks as I have, even if they are rated 400v. I they are mounted on the reverse side, it shoud be fine. But on the top side with that trace going right below the angled metal pin of the terminal block failure is programmed. FYI these are Phoenix terminal blocks from mouser and not some cheapo ebay stuff.
After all I think I might be able to repair the amp board.
The consequence of the -400 shorting to that trace caused a failure in both servos. The 1n914 were all shorted leading to a full short between +15 and -15. The 12V protection zener of the servo was shorted. On one board, the 4n25 measured a bit strange, so I will replace it. I don't know how to check the opamps. Will probably just replace them not to risk anything.
Furthermore the GRLV both suffered severe damage. I didn't bother to check which parts were dead, so I just replaced all the active parts and they seem to work again. There were no overheated parts or so, because I switched of immediately after the failure. I guess it was a voltage spike thing. What I know is that on one of the GRLVs the 1n4007 was also shorted, which is rated 1000v 1A, so here it is probably a current issue.
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18 minutes ago, mwl168 said:
Sorry for being thick - but why would a short on the B- header take out the LV regulator?
maybe there was a voltage spike on the ground because the trace the B- shorted to is going to gnd over a 25k resistor.
As a matter of fact both of them dont work anymore. I have already taken one apart and tested both lt1021. one of the two lt1021 is fried. the other one works.
Can anyone give me a tip on an easy way to test the opa134?
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I didn't use lead free solder. I used cardas quad eutectic.
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I didn't solder the big SOT223 tabs. Is it recommended to do that? Thought of easier removal in case of a problem. I agree that there might be a bit too much solder on the other SOT223 pins, but being small they are difficult to solder. Considering the general amount of solder used on the other joints, I was aiming to achieve "ok" joints as seen here:
The iron is around 370c or 430c. Don't remember exacty. What is recommended?
@Kevin For the HV lines, I use silverplated wire with teflon, they tin very easily and I doubt that this was the problem. When I removed the wires from the terminal blocks I did not have the impression of not tightened screws. But it's hard to exclude of course.
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9 minutes ago, JoaMat said:
This maybe?
I use this type of terminals. Better isolated to the board.
What brand is that? The ones I used are rated 400V. As discussed earlier in the forum there are no terminal block with higher voltage and the same size.
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Looks like I have found the culprit today. There was some charring on the B- header of one amp board... See for yourself.
To me it looked like there might have been a bit of flux from the B- pad to the trace adjacent to it. I cleaned all the board on the back side as well as possible, but how the f*** was I supposed to get that flux under the header? Do you guys always soak the boards on both sides? But even then, no brushing possible there.
The good news is that the transformer is alright. Unloaded voltages are fine.
The bad news is that the amp board is trash (I got two spare boards luckily). Unfortunately the two GRLV boards don't work properly anymore. I guess I will have to replace the amp board and replace all the active parts on the GRLV.
I still have to check the other amp board. Hopefully there was no damage to it. The GRHV seem to work properly (without load).
FYI the amp was used approx. 50h before this happend and ran about 15min on the day it happened.
What should I do to prevent this from happening with a new board and the other board?
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Ok then I think I have a bigger problem. I took out an LV board and tested it out of circuit without a load and it measured way above the 15v it should have...
This sucks... Looks like a major investigation...
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No I have not yet measured the transformer unloaded. I is too late in the evening to start working with live voltages... ;-)
So far I have only removed the toroid and measured the windings.
A preliminary visual inspection of the amp boards top sides, has not revealed anything. I will have to do that another day.
Btw: do you happen to know if the GRLV boards need a minimal load to properly regulated the voltages?
i'm on a roll... the kgsshv
in Do It Yourself
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Wow what a beauty! Very nicely done, internally as well as the chassis.
Congrats!