Simplistic Mosfet HV Shunt Regs - Page 433 - diyAudio
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Old 10th March 2014, 12:24 AM   #4321
Salas is online now Salas  Greece
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SSHV2 has more resolution and neutrality. Previous is bit rounder or "warmer".
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Old 27th March 2014, 10:40 AM   #4322
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Question 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
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Old 27th March 2014, 03:55 PM   #4323
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Diodes are OK?
If yes, check both KSA1381 & SK117GR.

Good luck

Felipe
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Old 27th March 2014, 04:06 PM   #4324
Salas is online now Salas  Greece
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Check if the dummy load is using up too much current also, if so it is starving the whole voltage setting parallel part of the reg.
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Old 27th March 2014, 07:26 PM   #4325
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Quote:
Originally Posted by Salas View Post
Check if the dummy load is using up too much current also, if so it is starving the whole voltage setting parallel part of the reg.
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
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Old 27th March 2014, 07:38 PM   #4326
AndrewT is offline AndrewT  Scotland
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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.
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regards Andrew T.
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Old 27th March 2014, 08:21 PM   #4327
Salas is online now Salas  Greece
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Quote:
Originally Posted by jcastellano View Post
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
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.
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Old 24th April 2014, 03:18 PM   #4328
zeeuw is offline zeeuw  Netherlands
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Dear Salas

Just faced a problem.
If F+ is shortcutted the S+ drops to zero.
The 12v zener does then not protect the KSA, as the KSA has a max BE of 5 volt
So KSA is broken down (as also the zener)
Pls comment

Sander
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Old 24th April 2014, 04:17 PM   #4329
Salas is online now Salas  Greece
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"Shortcutted" means F+ shorted to GND?
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Old 24th April 2014, 04:41 PM   #4330
zeeuw is offline zeeuw  Netherlands
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Yes
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