johnwmclean Posted March 20, 2015 Report Posted March 20, 2015 (edited) Double Post.... Edited March 20, 2015 by johnwmclean
JoaMat Posted March 20, 2015 Report Posted March 20, 2015 (edited) / Edited November 11, 2015 by JoaMat
mwl168 Posted March 21, 2015 Report Posted March 21, 2015 Thanks JoaMat. The LT1021 datasheet does refer to a two-terminal, shunt regulator mode as you stated. I also looked up the older versions of KGSSHV PSU that also used the LT1021 and it was connected the same way (V in pin open).
llamallama Posted March 23, 2015 Report Posted March 23, 2015 AU is now officially 230V, so 250V is just about the top margin. I'm in Sydney as well, I checked my outlets this weekend and it was 235V. No worries. Should check your line voltage, mine here fluctuates around 240V - 250V here in Sydney. The 230v spec could be a problem?
DHTGUY Posted March 25, 2015 Report Posted March 25, 2015 I'm getting closer to being able to fire up everything. I only have SR5 gold with normal bias - so I either need to build with both normal and pro bias, or I need to buy a pro bias headphone. I don't really want to buy the pro headphone until I know the amp is not going to go up in smoke. Question - any reason I shouldn't test the amp with SR5 and normal bias? Double Bias or Ebay pro phone for testing? I'll post PSU and Amp board pics shortly and would appreciate any "that doesn't look right" comments
spritzer Posted March 25, 2015 Report Posted March 25, 2015 It will work pefectly fine with a normal bias phone with 230VDC bias.
DefQon Posted March 25, 2015 Report Posted March 25, 2015 AU is now officially 230V, so 250V is just about the top margin. I'm in Sydney as well, I checked my outlets this weekend and it was 235V. Lucky you most places in Melbourne is still between 240 and 250v. The last two properties i had including my current house my mains is 245vac.
Earspeakers Posted March 29, 2015 Report Posted March 29, 2015 I only have SR5 gold with normal bias - so I either need to build with both normal and pro bias, or I need to buy a pro bias headphone. I don't really want to buy the pro headphone until I know the amp is not going to go up in smoke. Question - any reason I shouldn't test the amp with SR5 and normal bias? Double Bias or Ebay pro phone for testing? I have a minty SR5 gold coming in next week, really looking forward to it. On testing I have a 207 I use with a long burn in period. Probably unnecessary, but I'm more comfortable than using expensive and/or out of manufacture headphones. AU is now officially 230V, so 250V is just about the top margin. I'm in Sydney as well, I checked my outlets this weekend and it was 235V. You mean they just recently standardized this? Wow, that's unusual.
sorenb Posted March 29, 2015 Report Posted March 29, 2015 can the lsk389 be replaced by a pair of Toshiba 2SJ72-BL? I have 100 pairs of j72/k147 lying around for no use.
eggil Posted March 29, 2015 Report Posted March 29, 2015 (edited) I received several 4686 I bought from UTSOURCE and with the DY294 and they test at 1180 or so. The thing is it measures the same even if the transistor is not being tested. What gives? Edited March 29, 2015 by eggil
mypasswordis Posted March 29, 2015 Report Posted March 29, 2015 (edited) Mine does the same thing, except at around 1400V. I just assumed it's because the actual breakdown voltage is higher than the capability of the tester (higher with fresh batteries). It's a 1200V part so the real ones can definitely handle more than 1200V. Edited March 29, 2015 by mypasswordis
Pars Posted March 29, 2015 Report Posted March 29, 2015 can the lsk389 be replaced by a pair of Toshiba 2SJ72-BL? I have 100 pairs of j72/k147 lying around for no use. The LSK389 is an N-channel device while the SJ devices are P-channel. Here is a thread on diyaudio discussing at least the 2SK147 compared to the 2SK389 / 2SK170, etc. http://www.diyaudio.com/forums/solid-state/23954-2sk170bl-2sk369-mc-stage.html
sorenb Posted March 29, 2015 Report Posted March 29, 2015 The LSK389 is an N-channel device while the SJ devices are P-channel. Here is a thread on diyaudio discussing at least the 2SK147 compared to the 2SK389 / 2SK170, etc. http://www.diyaudio.com/forums/solid-state/23954-2sk170bl-2sk369-mc-stage.html I guess the "It's been pretty well discussed, but the 369 is the 'replacement' for the 2SK147." settles it - I have bunch of 147/72. Thnx Pars
johnwmclean Posted March 29, 2015 Report Posted March 29, 2015 I received a bunch of UTSource 4686s which look visually identical to the dbent parts. I happy to see they test good as well!
iwik Posted April 4, 2015 Report Posted April 4, 2015 (edited) Hi,Where is everyone getting their transistors from?Had a look on ebay , bdent and Chinese sellers. Are they worth buying from or do wehave to take Pot luck, buy them then test?.ThanksLes Edited April 4, 2015 by iwik
spritzer Posted April 4, 2015 Report Posted April 4, 2015 I've never come across fake 2SC4686A's but I'm sure they will surface once supplies dry up. I bought thousands of them from Japan and I've been selling them with the boards.
iwik Posted April 4, 2015 Report Posted April 4, 2015 What I was really referring to were the 2sa970 /2sc2240 ect for the amp. Researched the Mpsw series and they seemed to be hard to get also. Spotted the 2s series on ebay so wondered if they were worth taking a chance on them. Les
spritzer Posted April 4, 2015 Report Posted April 4, 2015 Some are real, some might be Chinese copies. That is true, especially of the 2SC1815. Nothing wrong with using MPSA units though
mwl168 Posted April 5, 2015 Report Posted April 5, 2015 (edited) Need help with testing/debugging the KGSSHVPSMINIFINALSTN9360 PSU board. The PSU is set up to deliver around 400 VDC (450 V Zener string, R29/R26 = 432K, R6 = 22.1K, ditto on the - side) Transformer is a 200VA Antek with dual 350v/290mA secondaries. It's overkill I know but they do not have a 150VA option and I thought the 100VA one's current rating is a bit on the low side. I wired one each 10ohm/ 2A inrush current limiter (Mouser part number 871-857153S100M54) on the L and N primaries and use a 3.15A slow blow fuse. I tested the PSU first with 15V secondaries to make sure I did not make elementary mistakes like insert the rectifiers or capacitors out of phase and it tested fine. When I connected the PSU with the 350v/290mA secondaries it blew the 3.15A fuse on start up. I did not see or smell any spark nor smoke and did not see any visible damage to the PSU. The output voltage showed around -170 VDC momentarily before the fuse blew ( I decide to test the PSU one section at a time ). My question; are my inrush current limiters under rated for this application? I did buy extras so would it help if I wire two in series on each primary? Or does this signify some more serious issues? Thanks for any insight or suggestion you can offer. Edited April 5, 2015 by mwl168
kevin gilmore Posted April 5, 2015 Author Report Posted April 5, 2015 a variac will make testing easier
mwl168 Posted April 5, 2015 Report Posted April 5, 2015 I borrowed a variance for testing but unfortunately it turned out to be defective.
spritzer Posted April 5, 2015 Report Posted April 5, 2015 You're in the US? Then a 3.15A fuse might be on the small side of things. Try 4AT and see if it holds up.
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