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High Rollers
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Everything posted by JoaMat

  1. Thank you. Eventually I found it, among a lot of other stuff. A test board for the battery module. I probably did it in spring 2020. Left heat sink has FJPF2145 (org. T2 it's 2SC3675) and right has 10M90S current sink set to 5 mA. Just find +250V and -560V and you are ready to go.
  2. The above misfortune was due to a battery problem in T2 amplifier. I replaced a mosfet j112(2sk246) and left the 10K trimmer in max position. My guess (I’m just an amateur but this is my theory) is the battery with the new mosfet tried to set voltage to more then 100V lower than expected. Resulting in damages to Q5, Q23, Q26 and D23 along with damages to the power supply. In order to find out what voltage cross 22R resistor R42 I put 27V from lab PSU from R42 to RV2 with 10K resistor in series. When measuring voltage cross 22K resistor of each battery I got 1V lower value at the battery with the new mosfet then the other three. That’s why I think there was more than 100V lower voltage at that battery. Now I have gotten really tiered of led batteries so I removed them and replaced them with those daughter boards. The amplifier has only modern components. To my ears it now works as good as the original DIY T2.
  3. Well, today I swinged my driver really hard and hit and killed +250v and -500V sections. Here are the casualties… …RIP. While repairing I also replaced ksc5026 in 250v section with 2sc3675 and that seems to work all right. Can you find them? By the way – the first version of KGSShv power supply used 2sc3380 along with 2sa1486, later replaced by ksc5026 and ksa1156 plus a Zener diode.
  4. Man or mouse? I always start with the Driver. https://www.youtube.com/watch?v=J2RoYgRhXjw
  5. Thanks James, my clock always tends to speed up when an amplifier needs attention. I have never used a variac when testing an amplifier. That’s way I asked.
  6. Is the T2 working at 50% of the mains?
  7. @HVRV, When you quote someone’s post it will appear in your post marked with the members name and time of the post in its own “window”. In that window you can’t make any changes. You have quoted me and written something I haven’t said. I don’t like that.
  8. @HVRV Please, Never ever make any changes within a quote. I urge you to make appropriate changes in your earlier posts.
  9. By the way... I have been made aware of that the mini T2 is marketed by a company unknown to me. They want $ 7,000 for it. It is an example of a villain's business model.
  10. Vilket land är det? ¿Qué país es? Which country is it? 是哪个国家?
  11. Sorry for a really slow response. Yes, the umbilicals are identical. Some background – my first electrostatic build was a KGSShv with a PSU with on board heat sinks in its own house. Second build was the DIY T2 and I liked the chassis design. Thereafter I have only built things (almost) with off board heat sinks. With T2 I built an original T2 PSU in a Modushop case. Later I built another T2 PSU with my own designed PCBs. That are the only PSUs I’ve built, along with the first KGSShc supply. But I’ve built a lot of Kevin designed amplifiers, and all have been power by those two T2 PSUs. I found the T2 PSU with its two identical umbilicals quite convenient. With the good quality Amphenol connectors it’s easy to connect/disconnect as wanted when I want to try/test one channel at the time. What about ground loops? I’ve read/heard about it, but so far, I haven’t, or I don’t know I have had ground loops. For me it’s more important I always have a safety ground connected. Therefor I’ll continue to use two identical umbilicals … P.S. I’ve had some issues with mini T2 that was solved by removing one 580V bias wire, so I probably have had a loop. problem. But safety ground wires will stay!
  12. Reduced “300V section” a bit more, to 150V. Now the high voltages are +/-400V, +220V, -310V and -460V. Graph below shows voltage cross 2sj79 (Q24/25) in blue and cross 2sk216 (Q26/27) in red during power on, wait 30 seconds and power off. I can’t hear sonically differences between original voltages and reduced voltages.
  13. A few years ago I replaced 2sj79 and 2sk216 with ksa1220 respective ksc2690 on both Blue Hawaii and T2 and that without changing any voltages. Below chart show voltage cross source and drain on T2´s Q26,Q27 during power on, 30 second wait and power off. So far I haven’t had any ksa1220 or ksc2690 blowing up. Today I reduced voltage further on my T2 PSU, 300V section now 200V. Seems to work as good as with 300V. High voltages are now +/-400V, +220V, -260V and -460V. The reduce voltage also lowered the maximum voltage on graph above to 200V
  14. A belated Happy Birthday!
  15. Belated Happy Birthday!!
  16. Thank you everyone. Wife and I had a nice medium long hike in beautiful winter weather. Wish you all well.
  17. Merry Cristmas to you all
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