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Old 20th October 2012, 11:25 PM   #3361
Salas is offline Salas  Greece
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The Zeners and/or the FET are suspicious. The FET especially goes pop without drama in over voltage. But check the CCS works after R1 change and possibly D1 or worse Q1. See at 12V as you say. It was left on how high a voltage input for 5sec?
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Old 20th October 2012, 11:45 PM   #3362
RollE2k is offline RollE2k  Sweden
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230V input voltage, and it may have been 10 sec, since i had time to take the multimeter measuring. 100mA load.
Will check the zeners also. By fet you mean the IRF840?
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Old 21st October 2012, 12:14 AM   #3363
Salas is offline Salas  Greece
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No, the JFET. 230V to 13.5V * 0.1A hmm, it gave Q1 some stick for 10 sec. Proceed to step autopsy.
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Old 21st October 2012, 12:41 AM   #3364
RollE2k is offline RollE2k  Sweden
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the Q1 sink didn't become that warm, but the R1 did burn, so it may have lived through it.
So i will try change the Q6 then, after i have checked the CCS part.
D3 seems like a candidate which may have died?
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Old 21st October 2012, 01:14 AM   #3365
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Yep.
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Old 21st October 2012, 06:52 PM   #3366
RollE2k is offline RollE2k  Sweden
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Changed all diodes, since they seemed to be broken (i got contact on them both ways with multimeter), then i changed the R1 and the JFET. Tried measure all resistors on board, and it looked right. tested the CCS with 12v between +input and +f which worked fine.
plugged everything in, started with 230v filtered input, and R1 burned again. Seems like something with the shunting?
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Old 21st October 2012, 06:59 PM   #3367
Salas is offline Salas  Greece
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Do the replaced diodes do the same conducting when off circuit? The 840's gate oxide could be hit when sparking, you are not left with much to check. That and the two BJTs.
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Old 21st October 2012, 07:06 PM   #3368
roger57 is offline roger57  Canada
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Sorry if this question has already been posted; did some searching but could not find. Please reply with posts if already answered or threaded.

Has anyone set up an SSHV2 with about 450V input (about 30mA at load required), and what components were changed (need to be changed) ?

Thanks,
Gary
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Old 21st October 2012, 07:14 PM   #3369
Salas is offline Salas  Greece
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If the Jfet has enough Idss you can got about 400V out without changing anything, about input over 400V me no, because the CCS Mosfets are 400V rated, though that condition is over run only just before the output develops, but at your risk.
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Old 21st October 2012, 07:15 PM   #3370
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RollE2K, does your DMM light up LEDS in diode mode? Has 2-2.5V? See that the LED can still light up to be sure before proceeding.
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