Simplistic Mosfet HV Shunt Regs - Page 372 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 31st December 2012, 10:26 AM   #3711
diyAudio Member
 
Brouilly's Avatar
 
Join Date: Mar 2009
Location: London
Quote:
Originally Posted by Salas View Post
What changed in the full circuitry, at what point they started acting up? Are all semis in the regs showing working voltages like VGS, VBE? Was there a certain incident or revision, or an active part likely to have changed behavior in the client? A rewiring? Have you actually seen AC waveforms riding the DC line on a scope? When oscillating weird things happen all over, so its not unlikely for oscillation actuallly happening. Are there any capacitors from rail to ground or series connected parts on the rail after the reg's output? If yes, what are they?
Did some more testing this morning. Both regs work fine on thier own, but they go instable when running together. When both regs are running together I can not get anywhere near the voltage required for the circuit with the trim pots.

There is definite LF oscillation, when inputs are shorted there is large instability in the low end when reading a live trace. And there is a pulsing AC waveform on the DC rail. But this is not present when using one reg at a time.

The setup is;

CRC - individual RC per reg - SSHV2 - circuit. There are no filters after the regs just OPT and input stage anode load.

This is a new issue as I have been testing for a couple of weeks with no trouble at all, but after a break and coming back to it this has happened. I have not made any major changes to the ciruitry, only adjusting bias.

All transistors have working voltages. Is there anything else I can check?

Thanks
__________________
Broke solderer with delusions of grandeur
  Reply With Quote
Old 31st December 2012, 04:03 PM   #3712
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Only thing I can theorize is as the impedance of the regs rises towards DC due to finite capacitive filtering (10uF) and semis characteristics, some weird loop takes form in the specific circuitry and/or build. What values is the CRC?
  Reply With Quote
Old 31st December 2012, 04:16 PM   #3713
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Try to differentiate value of the last capacitor in one CRC for a test. By adding one extra at one reg's input as much close to it as you can.
  Reply With Quote
Old 5th January 2013, 03:07 PM   #3714
diyAudio Member
 
Brouilly's Avatar
 
Join Date: Mar 2009
Location: London
Values are 47UF - 1K - 220uF - 1K

I placed a final 47uF and small R right infront of the boards and they appear to be working fine. I will do the same with the second channel and hopefully that issue will not come back.

Thanks for your help!
__________________
Broke solderer with delusions of grandeur
  Reply With Quote
Old 7th January 2013, 05:56 AM   #3715
diyAudio Member
 
Join Date: Aug 2005
Hi Salas, wishes of happy new year.

I need your help if possible, yesterday working late and tired, I did a stupid mistake with one working SSHV2 board, I connected my meter probes set to measure on the 20A range, to the output of the board, wanting to measure voltage

Of course this produced a nice small flash on the terminals/probes, and the regulator stopped working. The led is still on, but now I get only around 6,4V on the output.

What I need is for you to tell me in your opinion what should be changed to avoid taking all transistors out.
Many thanks.
  Reply With Quote
Old 10th January 2013, 10:37 AM   #3716
diyAudio Member
 
Join Date: Apr 2012
Hi i have build my salas, but i have another board, little smaller. But similiar to the org salas. When I have attached power suply R1 burned, when i mesure the R1 on the board it has 97R, when I measure R1 in another board it have 120R( i have two salas's) i have 280vdc power suply, my target is 260vdc, for now my dummy load is 17k(15mA in 260vdc)What is going on? please help me.A have add zip with the eagle files.
Attached Files
File Type: zip Salas.zip (53.2 KB, 66 views)
File Type: pdf drSlas.pdf (14.0 KB, 74 views)
  Reply With Quote
Old 10th January 2013, 01:47 PM   #3717
diyAudio Member
 
Join Date: Apr 2012
I have search for the bugs, but nothink found. So i add a pictures.
Attached Images
File Type: jpg HPIM2683.JPG (80.7 KB, 313 views)
File Type: jpg HPIM2684.JPG (91.0 KB, 273 views)
File Type: jpg HPIM2685.JPG (82.3 KB, 251 views)
File Type: jpg HPIM2686.JPG (81.5 KB, 245 views)
File Type: jpg HPIM2687.JPG (86.6 KB, 231 views)
File Type: jpg HPIM2688.JPG (85.2 KB, 73 views)
File Type: jpg HPIM2689.JPG (84.2 KB, 84 views)
  Reply With Quote
Old 10th January 2013, 02:03 PM   #3718
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Why you have these logn cables for IRF840? If I remember correctly the gate resistor have to be near the IRF840.
  Reply With Quote
Old 10th January 2013, 02:10 PM   #3719
diyAudio Member
 
nicoch58's Avatar
 
Join Date: Oct 2004
clean well the pcb....
__________________
Sic58
  Reply With Quote
Old 10th January 2013, 02:14 PM   #3720
diyAudio Member
 
Join Date: Apr 2012
Sorry for pcb, for now dont have cleaner. I have measured thad R1 and R11 are domaged. Long calbes becouse i dont have site for radiator near the pcb. It is pasible that salas dont work coz this gate resistor? I will power on next salas.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Regs - Shunt vs Series richie00boy Solid State 42 14th March 2013 06:45 PM


New To Site? Need Help?

All times are GMT. The time now is 01:54 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2