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Old 13th April 2013, 06:15 PM   #1751
stajo is offline stajo  Sweden
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Quote:
Originally Posted by iko View Post
That looks bad! If it works well and your measurement method is good, it should look like a flat line. The attached image, an hv shunt reg of my own, at 500uV/div.
Well, I did a new PSU today.

I started to misstrust the other trafo and the AZ1 that closes up to its limits. Its a C-L-C followed by double R-C to each SSHV. They get 330 V in with about 85 mV ripple in, measured with both DMM and scope. SSHV out is 270 VDC and 76 VRMS. I have set current testpoints at 0,400 V for 40 mA.

Dummyload is 13k5 on each SSHV for 20 mA.

Are the SSHVs malfunctioning? Where shall I search?
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Old 13th April 2013, 06:35 PM   #1752
stajo is offline stajo  Sweden
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Sinks get lukewarm, both CSS and shunts that are cooled by a 3 mm alu bottom plate
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File Type: jpg 6V6 001 (3000x2000).jpg (724.9 KB, 112 views)
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Old 13th April 2013, 06:38 PM   #1753
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Staffan, How much ripple do you have with the new PSU?
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Old 13th April 2013, 06:41 PM   #1754
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As I say above: "They get 330 V in with about 85 mV ripple in, measured with both DMM and scope. SSHV out is 270 VDC and 76 VRMS."

But I ment ofc 76 mVRMS ripple out
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Old 13th April 2013, 06:43 PM   #1755
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So you have 9mV of ripple?
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Old 13th April 2013, 06:44 PM   #1756
Salas is offline Salas  Greece
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@ Stajo
Your #1746 post shows some undulation at about 0.32mS period. That is 3100HZ. Too high for being hum too low for being oscillation. In your #1752 picture I see long input cabling and some central GND node to it. Decouple the regs inputs right across their +IN/0V connector with small film caps and see if there is a problem with the raw DC part grounding scheme by trying alternatives.
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Old 13th April 2013, 06:51 PM   #1757
Salas is offline Salas  Greece
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Quote:
Originally Posted by stajo View Post
As I say above: "They get 330 V in with about 85 mV ripple in, measured with both DMM and scope. SSHV out is 270 VDC and 76 VRMS."

But I ment ofc 76 mVRMS ripple out
When driving one MegOhm input (or ten MegOhm for probe X10) from milliOhm source impedance you have a very receptive measurement loop to any kind of interference also. Use the short point ground coil instead of your GND crock. Remeasure. See if you get the same waves. See with and without remote sense. Although you use self made SSHV1 also that does not usually employ sense wires. Give us a clear account of the above so we can know the problems.
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Old 13th April 2013, 07:03 PM   #1758
stajo is offline stajo  Sweden
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A 10 uF over each. Ripple in and out
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File Type: jpg 6V6 002 (3000x2000).jpg (721.3 KB, 101 views)
File Type: jpg 6V6 003 (3000x2000).jpg (811.8 KB, 92 views)
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Old 13th April 2013, 07:19 PM   #1759
stajo is offline stajo  Sweden
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Quote:
Originally Posted by Salas View Post
Use the short point ground coil instead of your GND crock. Remeasure.
I've got this crap to measure HV

And some pix on ripple out. First with noice unfiltered, second with a 10 kHz lowpass filtering
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File Type: jpg 6V6 004 (3000x2000).jpg (756.2 KB, 82 views)
File Type: png SSHVut1.png (20.0 KB, 36 views)
File Type: png SSHVut2.png (14.5 KB, 26 views)
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Old 13th April 2013, 07:20 PM   #1760
Salas is offline Salas  Greece
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Quote:
Originally Posted by stajo View Post
A 10 uF over each. Ripple in and out
Can it read HZ at mV level? Press the frequency button for input and output probing. Its suspiciously same level for in and out now, it could all be riding on the ground loop. Dress the long output cables in twisted pairs. Force pair, sense pair. Remeasure. Null the sense pair by jumpers at F0,S0 F+,S+. Remeasure.
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