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Old 20th July 2011, 10:41 AM   #371
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Arrived tubes 6N2P-EV
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Old 21st July 2011, 10:29 AM   #372
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Just arrived today the 1578=6SN7=TOP RUSSIAN 6N8S Tube FOTON MATCHED PAIR 60s
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Old 22nd July 2011, 08:32 PM   #373
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Default Oops - should that smoke be there?

Hmm, got to the end of build and started testing. Rather warm resistor just before the HV shunt. Its 6W 120R which I thought should be ok. I have double checked the wiring and it is all as per my plan so I think must be something wrong with my interpretation of this thread. I attach it here. Not exactly a professional diagram but it is functional. I need to approach this with a fresh pair of eyes in the morning else I might end up frying something! Anyone spot obvious errors on this?
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Old 23rd July 2011, 03:04 AM   #374
Salas is online now Salas  Greece
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Measure the voltage drop across the 120R. Divide it by 120R. Should be around 5V for a circa 40mA CCS sourcing from that CRC filter. That's only 0.2W. Some 1W resistor should hold forever. If the drop is high and the current is strong then its heating up a 6W resistor enough and gives away wrong current draw down the reg way. Check on reg's R1. Again Vdrop/R. Is it 30-40mA which is wise for the application? If the functioning is OK but the current is much, you should up R1 and current should lower. Else, you got something wrong or burned in the reg. See if you have a burned 9610 if current is wild and won't listen to R1 changes. Check there is about 4V Vgs on the Mosfets. (DVM on G-S). No Vgs=dead. Also wire your 10K LM317 trimmers as shown for R8 in the SSHV, the hand drawn PSU just shows them varying, not exact for connection.
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Old 23rd July 2011, 08:10 AM   #375
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Did you connected the GND of SSHV to GND filaments?
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Old 23rd July 2011, 04:36 PM   #376
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9610's are prone to blowing, I wonder if it's that. Is there a simple way to test a IRF9610?
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Old 23rd July 2011, 05:03 PM   #377
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I think I have found the source of the problem. Stupidity on my part. Instead of a 220R to the gate of the IRF840 I used a 220k. That will teach me to be doing this at 2am! Now to see what the damage is I need to test those components that could be suspect. I would have thought the IRF's 9610 and 840. I do not have any spares handy to compare them with so am looking for a way to test prior to ordering replacements on Monday.
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Old 23rd July 2011, 05:58 PM   #378
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Measure Vgs when in circuit, or google how to test off circuit with a diode tester DMM setting or Ohm meter.
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Old 24th July 2011, 10:52 PM   #379
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I switched the 120R for a very beefy 10K just so I could see if circuit intact. Everything seemed to light up and be stable. Difference across the 10K is 290 ish. I have not got much further with testing rest yet. LEDs are happily lit. I have checked all resistors to make sure all ok and seem to be. It's the 9610 that concerns me. Reading Salas last post if I change values of R1 I should be able to see if 9610 is intact. I could replace irf9610, the 840 and mje350 just for good measure. I have googled how to test these and seems playing with 9v battery is best way if taking them out of circuit. That will be next step if cannot prove they are intact tomorrow. Anyway valves all glowing reassuringly so looks pretty of nothing else:-). I will let you know how further testing goes tomorrow. Thanks all.
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Old 25th July 2011, 12:18 AM   #380
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290V across 10K means 29mA. Which sounds normal with your R1. I told you, you may measure voltage difference between gate and source of each Mosfet when the circuit is alive. You should find ~4V if they are OK. Get rid of D1 to make sure it does not perplex things and check with a CRC resistor value that brings 320V DC in to the reg and adjust for 300V DC out. Say 1K 3-5W.
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