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ang728

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  1. Same Here,also uses MJL21193/94 on other builds
  2. LT1021-5 won't work in shunt mode,add 1 wire for pre-reg to Vin of 1021 will do fine.I used it in my 8.4VDC supply
  3. Here to bump the thread up. Does anybody knows the spec of SRM-007T transformer? I am currently working on a SRM-007T repair and the transformer showing signs of leakage on one secondary HV rail. Measured about 160VAC w/o load and showing some magic smokes... also DCR on corrupted rail is lower than normal ones (79ohms vs 50ohms).so I feel theres some insulation breakdown in the sec side. I ask some workshop to see if they can rewind the transformer.they ask me detail about specs of all the rails. from schematics KG kindly provided me.I am sure HV should be two 270VAC ,filament is 12.6V CT (6.3-0-6.3).but I still need: AC Voltage on LV side (I assumed 30VAC CT) current rating on all secondary side rails thanks!
  4. yeah that's for ZF/SS switch and protector hat PCB ,but can do better placement on next revision
  5. so after some fiddling around , now my CFA3 working perfectly.I replaced all my old stock BC546/556 to newer parts with roughly matching,offset still 40mV w/o Servo but no big difference switching back to 300ohm maybe my problem comes from some crooked old BC parts...? I dunno but fixed anyway lol
  6. Yes , I solve this problem from this post , a big help.but still need more fiddling to find out and that's why I like HC more than HF 😭
  7. yes that's usually what I do but maybe not on my case this time.hope to see others experience about it.
  8. Finished building CFA3 Ver1.21 recently.But offset reading seems off ,about 0.8V relative to gnd and 0.2V after solving oscillating issue ,VO+ to VO- also high as 0.2V and bias went huge bump when switching ss to zf with oscillation on scope.I was quickly solving the problem by pulling 600pf,20pf caps form the mentions in this thread. After some wild goose chase then I noticed a slight difference between schematic and board silkscreen.R211,R222,161,R262 value at current mirror is 680ohms but showing 300ohm on PCB. now I have about 40mV offset w/o servo at each side with 680ohm resistor,haven't done any further test but I think I can have a good sleep tonight Scrolling through the thread and it seems nobody mentioned .Not sure if that's a issue but just a heads up
  9. the pin header I use is 127-1-4010-8002-310 made by Nextron. Or you can search "Nextron 2.54mm round pin" on Ebay
  10. But I have different results here do you have other changes on the board like zener diode that KG mentioned ?
  11. Tried GeneSic G2R1000MT17D to power BH with no luck, showing similar behavior johnwmclean mentioned,negative rail will drop significantly and came back to about 395V after some random voltage probing. not sure if raise up the 5pf cap value would help
  12. using 18VAC*2 secondary would be good for +-20VDC outputs
  13. Some similar experiences here,but microchip MSC750SMA170B instead. Was using it on my GRHVs, same issue when PSU was measuring normal under no load (both rail measured around 401V),but dropping to about -180V on B- and B+ also seems a bit off (about 391V) as powering carbon amp which is using now precious C2M100070D. Everything back to normal as I swapped microchip SiCs back to C2Ms... but I would continue trying any alternative option on GRHV.
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