SSHV2 problem
Dear friends,
I have just finished an SSHV2 and I am having a problem with it. I bought the kit from Tea-Bag and I feel it is well stuffed. I am feeding it with 180V raw DC, I can adjust the current (in my case 60ma, so at TP I read 600mv) but I only got 25 volts output. Adjusting R11 I con go up to 40 volts but no more. The led is lit and I tested R11 to be in the range of 1k as stated in the manual. The sink of the IRF840 is cold whatsoever.
Any clues?
Best Regards
Jorge
Dear friends,
I have just finished an SSHV2 and I am having a problem with it. I bought the kit from Tea-Bag and I feel it is well stuffed. I am feeding it with 180V raw DC, I can adjust the current (in my case 60ma, so at TP I read 600mv) but I only got 25 volts output. Adjusting R11 I con go up to 40 volts but no more. The led is lit and I tested R11 to be in the range of 1k as stated in the manual. The sink of the IRF840 is cold whatsoever.
Any clues?
Best Regards
Jorge
Hi Salas,
I am using a dummy load rated at 3.3k and 17watts. I am trying to achieve 200v with 60ma current ( 40 for the phono preamp and 20ma spare ). My transformer is rated at 180v sec 100ma, after rectifier and cap bank, should be around 240volts, plenty enough for regulation.
Hi Felipe,
Checked everything and look fine. Gracias...
Thanks and regards,
Jorge
Your transformer secondary has too low a current rating for a continuous 60mA+CCS.
You need at least a 120mAac secondary but much cooler to use a 240mAac rated secondary.
If you want to source 40mA into your dummy load @ 200Vdc, then the load should be around 5k. 15W to 20W is sufficient rating.
That you are getting only 25Vdc at the output indicates another fault.
You need at least a 120mAac secondary but much cooler to use a 240mAac rated secondary.
If you want to source 40mA into your dummy load @ 200Vdc, then the load should be around 5k. 15W to 20W is sufficient rating.
That you are getting only 25Vdc at the output indicates another fault.
First test is to use about 5K dummy load. Since the shunt part tries to do some voltage now and adjusts but stays low, you must eliminate the heavy test loading parameter first and then see what might be next or not. Lets hope that the large in-out differential it suffered did not manage to take out some semis. After better set/repaired you should evaluate the transformer's temperature also because its marginally current rated as Andrew noted.
Here is a relevant thread: http://www.diyaudio.com/forums/tube...mode-mosfets-available-experience-anyone.html
Just one last question. I'm planning on building a simple 6072 gainstage with cathode follower for my DAC and probably need to lift the DC heaters relative to ground. Is it as simple as making a voltage divider on the output of the SSHV2 and "ground" the heater supply there or do I need some sort of capacitor as well?
You normally create a divider out of high value resistors (in the hundreds of kOhm) across a filter capacitor after the rectifier and before a reg. You put them there to double as bleeders for the PSU to discharge after each use and stay safe. Their ratio is calculated for deriving the desired heaters lift level voltage. Their sum value and power spec are calculated to give 2-3mA bleed given the specific HV level across the PSU cap. You additionally filter the bottom resistor with a capacitor across it. Because the impedance is high a relatively small uF value is enough.