Pars Posted March 26, 2023 Report Share Posted March 26, 2023 For RK50, you can look at Octopart here: https://octopart.com/rk50114a0001-alps-7850315. Otherwise, the TKD 4CP2500s are well thought of, and the 4CP601s aren't too far behind. Much cheaper. As for board placement, I would guess those that place the board at the rear do so to keep them close to the input jacks (noise). This would normally require that the volume pot use a shaft extender and also be placed at the back. For raising the resistors, 2mm should be plenty. Quote Link to comment Share on other sites More sharing options...
Reima Posted March 26, 2023 Report Share Posted March 26, 2023 Thanks Pars. Quote Link to comment Share on other sites More sharing options...
johnwmclean Posted March 26, 2023 Report Share Posted March 26, 2023 6 hours ago, Reima said: I see some builds have the amp boards at the back of the chassis and others at the front. Is there any benefit (sonic or otherwise) to putting them at the front or back? As a rule of thumb try and keep the transformer as far away from the amp boards as possible. Board placement depends a great deal on whether you’re building a two box or one box chassis. Implementing a two box with an an external psu you do have the luxury of having the amp boards at the back close to the inputs and like Pars mentioned you can then use a long shaft for the volume pot. Btw I’ve not had any had hum issues when using fully encapsulated transformers. Quote Link to comment Share on other sites More sharing options...
Reima Posted March 28, 2023 Report Share Posted March 28, 2023 @johnwmclean thank you. I should have taken the hint from the DIY T2 where the volume pot etc. are at the back of the chassis. I will most likely go with an external psu. Quote Link to comment Share on other sites More sharing options...
Reima Posted April 5, 2023 Report Share Posted April 5, 2023 I have completed the GRLV, have not tested it as yet, 1 Quote Link to comment Share on other sites More sharing options...
Pars Posted April 13, 2023 Report Share Posted April 13, 2023 Tested the two C2M devices I pulled out of the Carbon board last night on one of those cheap chinese device testers. One of them tested as an NPN, the other as a MOS FET. Another new one tested as a MOS FET as well, so guessing the one that thought it was an NPN was the bad one. Tossed it. 1 Quote Link to comment Share on other sites More sharing options...
MLA Posted April 14, 2023 Report Share Posted April 14, 2023 Good riddance Quote Link to comment Share on other sites More sharing options...
Guest Posted April 16, 2023 Report Share Posted April 16, 2023 Hi all maybe someone has a link to kgsshv carbon schematic I try to find, but I find either broken links or fragments of the schematic or documents that are not downloadable here( Quote Link to comment Share on other sites More sharing options...
Pars Posted April 16, 2023 Report Share Posted April 16, 2023 (edited) a Edited April 17, 2023 by Pars Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted April 16, 2023 Report Share Posted April 16, 2023 i was going to be much less friendly. the file you are looking for is where it should be. Quote Link to comment Share on other sites More sharing options...
Guest Posted April 17, 2023 Report Share Posted April 17, 2023 (edited) yes it seems to be a problem with my browser if i just click on the document it tries to load but nothing happens but if i copy the link to the document and open it in a new tab - everything works very strange behavior and the links to gilmore.chem.northwestern.edu seem to be just outdated some of them are quite old, it looks like that hosting is just outdated Edited April 17, 2023 by usa_love Quote Link to comment Share on other sites More sharing options...
bbest Posted April 27, 2023 Report Share Posted April 27, 2023 PSU for both: Carbon and GG (Ground Grid). With delay board for tubes filaments. Compact 22AWG wires can handle 700v DC, double shielded. Quote Link to comment Share on other sites More sharing options...
Shawn Posted October 31, 2023 Report Share Posted October 31, 2023 Another idea of mounting those heat generators using the JST jumpers. Quote Link to comment Share on other sites More sharing options...
simmconn Posted October 31, 2023 Report Share Posted October 31, 2023 Be aware that the JST XH series is only rated for 250V AC/DC. Quote Link to comment Share on other sites More sharing options...
audiostar Posted October 31, 2023 Report Share Posted October 31, 2023 Yes, better would be something like the MATE-N-LOK series from TE, for 3-pin Mouser # 571-1-770873-0 and # 571-1721661 for the cable side. Quote Link to comment Share on other sites More sharing options...
Shawn Posted November 2, 2023 Report Share Posted November 2, 2023 On 10/31/2023 at 1:19 PM, audiostar said: Yes, better would be something like the MATE-N-LOK series from TE, for 3-pin Mouser # 571-1-770873-0 and # 571-1721661 for the cable side. Updated for 571-1-770873-0. 1 Quote Link to comment Share on other sites More sharing options...
audiostar Posted November 2, 2023 Report Share Posted November 2, 2023 Marvelous! Here the crimp sockets for the cable side connectors, Mouser # 571-770988-1 1 Quote Link to comment Share on other sites More sharing options...
s_r Posted August 8 Report Share Posted August 8 (edited) One of the big F&T 680uF/550V caps in my carbon PSU decided it wanted to pop mid-listen. Was the v1.7 split PSU boards, specifically the one with the LV supply (the cap closer to the LV section was the one that popped). Certainly left a big mess of electrolytic fluid to clean up all over the inside... The other 680uF caps were also starting to bulge, so I replaced all four. It's concerning that all the 680uF caps would start doing that after roughly 9 years, especially when there was a period of about 2 years where the amp simply wasn't turned on at all. Could the amp's heat be accelerating this? Anyway, the cap seems to have taken out some other parts in the -450V supply with it. Getting about -30V at the output and around the same at the drain & source of the DN2540. I can get other measurements later if needed. Anything else it might've taken out besides the 10M90S (Q1/Q7)? Edited August 8 by s_r Quote Link to comment Share on other sites More sharing options...
MLA Posted August 8 Report Share Posted August 8 GRHV does not fail gracefully... most or all of the active parts might need replacing. Sören B posted a good guide for trouble shooting somewhere. Quote Link to comment Share on other sites More sharing options...
s_r Posted August 9 Report Share Posted August 9 (edited) Well I've tried replacing the C2M1000170D, 2x 10M90S, and the DN2540 & got similar behavior. Then I swapped out the LT1021, same story. Then I swapped out all of the sand save for the four STTH512FPs (since I apparently don't have any spares of those). Now it slowly climbs to about -200V & hovers there. Unless only swapping out some parts at a time killed the previous replacements, or unless it's just the STTH512FPs, not sure what else could be the cause of the issue. Edited August 9 by s_r Quote Link to comment Share on other sites More sharing options...
ang728 Posted August 9 Report Share Posted August 9 did you check 2N3904 and 24V Zener ? they also could gone with faulty GRHV Quote Link to comment Share on other sites More sharing options...
s_r Posted August 9 Report Share Posted August 9 (edited) 2N3904 was also replaced. Doing a diode check the 24V zeners & the 1N4007s get the same measurements as the ones on the working +450V supply. Haven't diode-checked all four but two of the STTH512FPs measure the same as on the working supply as well. Edited August 9 by s_r Quote Link to comment Share on other sites More sharing options...
s_r Posted August 13 Report Share Posted August 13 It must've been either the STTH512Ps or the 24V zeners (or both), since I replaced those and now I'm getting -461V at output. Likely replaced more than what was necessary but whatever, peace of mind is worth more than the parts cost. Should be able to zip everything up and have this carbon playing music again tonight. 2 Quote Link to comment Share on other sites More sharing options...
judo Posted August 13 Report Share Posted August 13 Congratulations! I have the same problem with my carbon. Both of the big capacitors in the negative supply died. It happened a few months ago but I can not persuade myself to start the repair until now. As I checked it again I see one of the capacitor in the positive supply is bulging too. These are from the first group buy I think. Where are yours from? So the advice is replace all the sands (and check the passives in between) the less time consuming? ; Quote Link to comment Share on other sites More sharing options...
s_r Posted August 13 Report Share Posted August 13 1 hour ago, judo said: Congratulations! I have the same problem with my carbon. Both of the big capacitors in the negative supply died. It happened a few months ago but I can not persuade myself to start the repair until now. As I checked it again I see one of the capacitor in the positive supply is bulging too. These are from the first group buy I think. Where are yours from? So the advice is replace all the sands (and check the passives in between) the less time consuming? ; The caps were from the F&T cap group buy here years ago. Definitely going to be keeping a closer eye in the coming years for signs of them starting to bulge again. Like I mentioned earlier it's worrying that they would act this way after only so many years... One would expect caps to last at least a few decades of normal usage. I probably replaced more of the sand than necessary, but the 24V zeners should likely be replaced too as ang728 mentioned. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.