If you need assistance, please send an email to forum at 4hv dot org. To ensure your email is not marked as spam, please include the phrase "4hv help" in the subject line. You can also find assistance via IRC, at irc.shadowworld.net, room #hvcomm.
Support 4hv.org!
Donate:
4hv.org is hosted on a dedicated server. Unfortunately, this server costs and we rely on the help of site members to keep 4hv.org running. Please consider donating. We will place your name on the thanks list and you'll be helping to keep 4hv.org alive and free for everyone. Members whose names appear in red bold have donated recently. Green bold denotes those who have recently donated to keep the server carbon neutral.
Special Thanks To:
Aaron Holmes
Aaron Wheeler
Adam Horden
Alan Scrimgeour
Andre
Andrew Haynes
Anonymous000
asabase
Austin Weil
barney
Barry
Bert Hickman
Bill Kukowski
Blitzorn
Brandon Paradelas
Bruce Bowling
BubeeMike
Byong Park
Cesiumsponge
Chris F.
Chris Hooper
Corey Worthington
Derek Woodroffe
Dalus
Dan Strother
Daniel Davis
Daniel Uhrenholt
datasheetarchive
Dave Billington
Dave Marshall
David F.
Dennis Rogers
drelectrix
Dr. John Gudenas
Dr. Spark
E.TexasTesla
eastvoltresearch
Eirik Taylor
Erik Dyakov
Erlend^SE
Finn Hammer
Firebug24k
GalliumMan
Gary Peterson
George Slade
GhostNull
Gordon Mcknight
Graham Armitage
Grant
GreySoul
Henry H
IamSmooth
In memory of Leo Powning
Jacob Cash
James Howells
James Pawson
Jeff Greenfield
Jeff Thomas
Jesse Frost
Jim Mitchell
jlr134
Joe Mastroianni
John Forcina
John Oberg
John Willcutt
Jon Newcomb
klugesmith
Leslie Wright
Lutz Hoffman
Mads Barnkob
Martin King
Mats Karlsson
Matt Gibson
Matthew Guidry
mbd
Michael D'Angelo
Mikkel
mileswaldron
mister_rf
Neil Foster
Nick de Smith
Nick Soroka
nicklenorp
Nik
Norman Stanley
Patrick Coleman
Paul Brodie
Paul Jordan
Paul Montgomery
Ped
Peter Krogen
Peter Terren
PhilGood
Richard Feldman
Robert Bush
Royce Bailey
Scott Fusare
Scott Newman
smiffy
Stella
Steven Busic
Steve Conner
Steve Jones
Steve Ward
Sulaiman
Thomas Coyle
Thomas A. Wallace
Thomas W
Timo
Torch
Ulf Jonsson
vasil
Vaxian
vladi mazzilli
wastehl
Weston
William Kim
William N.
William Stehl
Wesley Venis
The aforementioned have contributed financially to the continuing triumph of 4hv.org. They are deserving of my most heartfelt thanks.
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
I wasnt sure if i should start a new thread :/
OK sooo... coil is dead, i dont have an oscilloscope so i cant scope anything just my multimeter.
Coil is running 100% ok-->switch to cw mode(through a small cap value)-->BANG!!!--->Blew my 120vac traces on my board :( (noob mistake)--> reconnect with heavy wire, no output...--> What could have died form that???
NO LOAD, I am just powering up the low voltage/driver side... The UCC's are loaded with the gdt and a 1uf cap.
I replaced all the chips and ran it to see if i could hear a small clicking sound of the low voltage side (click=working), nothing. All the chips are new and are getting the correct voltage, in fact the UCC were getting hot after a couple seconds but the lm7812 was cool. I checked the 1uf caps (dont really no what to do)
tested fine, put them back in and flipped the switch, after about 5 seconds the 555 ic releases smoke. (WHAT???) i killed now back to back.
Im going to replace the lm7812 as stuff is shorting out but it stays cool O.o ( high current draw without heat on the lm7812) not a good sign.
My question is what could have been fried for my 120v bus shorting out?? The GDT is still connected but im not power the Half bridge during these tests, Im really confused
UPDATE*****
I removed all the ic's and powered the board, the two 1uf caps meant for the UCC's got burning hot...
I put the 555 back in all alone, and it still got very hot in a couple seconds
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
I think I blew all or my decoupling caps, there all tantalum caps and they dont handle ripple very well or at all.
UPDATE: Turns out there was a short on the 3rd and 4th pin on the 555 time, I replaced the .1uf caps with ceramics but i dont have any 1uf caps... I tried to power up the board with the gdt load and the 74hc14 got super hot.
Can the driver not run without the decoupling caps for the UCC chips????
Im a noob to SSTC design and circuity, its painful
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
ZakWolf wrote ...
Coil is running 100% ok-->switch to cw mode(through a small cap value)-->BANG!!!--->Blew my 120vac traces on my board :( (noob mistake)--> reconnect with heavy wire, no output...--> What could have died form that???
many chips could have died from that.
To start, your mosfets are likely done for. You may or may not have blown the 74hc14 and UCC's too. Check for continuity between Vcc and GND pins with your multimeter.
Did you use 120VAC for CW mode??? You cannot do that with the IRFP260 on the mini sstc!! like 30VAC maximum for CW, and dont expect the IRFP260's to last very long if you do. Always fuse the AC input with a 5AMP fuse or less. When I use the SSTC5 in CW mode to light my plasma tubes, I never have to go over 20VAC to get them to light up. Sparks will be less than an inch or so too. Anything over that is danger zone for the poor little fets
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
Physics Junkie wrote ...
ZakWolf wrote ...
Coil is running 100% ok-->switch to cw mode(through a small cap value)-->BANG!!!--->Blew my 120vac traces on my board :( (noob mistake)--> reconnect with heavy wire, no output...--> What could have died form that???
many chips could have died from that.
To start, your mosfets are likely done for. You may or may not have blown the 74hc14 and UCC's too. Check for continuity between Vcc and GND pins with your multimeter.
Did you use 120VAC for CW mode??? You cannot do that with the IRFP260 on the mini sstc!! like 30VAC maximum for CW, and dont expect the IRFP260's to last very long if you do. Always fuse the AC input with a 5AMP fuse or less. When I use the SSTC5 in CW mode to light my plasma tubes, I never have to go over 20VAC to get them to light up. Sparks will be less than an inch or so too. Anything over that is danger zone for the poor little fets
yeah i was powering it with 120v oops im going to get new decoupling caps soon and try everything again
EDIT: Whats a good way to test the bridge to see if everything is still working? And can i still test the low voltage side without the caps for the UCC's or will it not work correctly ?
I really thought this was going to be a simple fix
Registered Member #7267
Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407
take the mosfets off the board and check the pins for continuity. No pin should have continuity to another. I wouldnt recommend testing the UCC's without decoupling caps. It really shouldnt be a complicated fix. It's all a learning experience really. Having a problem like this is good in the long run because once you fix it, you will know how to better isolate the problem and fix it if it happens again in the future All you gotta do is just test the chips with an ohm meter/multi meter making sure that no pins are shorted where they shouldn't be (i.e. Vcc to GND).
After putting 120VAC through your bridge CW mode like that, I wouldnt trust that the low voltage side is perfectly fine after that. just replace any or all chips on the low voltage side that is getting hot or not working. If it was working the first time/not getting hot (not cw mode) but now it is not, chances are its blown and it would be a better idea to just replace it. That's just my opinion though. As for dead resistors and caps etc.. its up to you if you want to pull everything off the board and test it. Usually you can just look closely at the part and if you see any sign's of excessive heat/burn then just replace that part. For example if your decoupling caps and resistors have turned like a darker color brown in the center then it's probably a good idea to replace it whether it still test good or not, but again that's just me.
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
Physics Junkie wrote ...
take the mosfets off the board and check the pins for continuity. No pin should have continuity to another. I wouldnt recommend testing the UCC's without decoupling caps. It really shouldnt be a complicated fix. It's all a learning experience really. Having a problem like this is good in the long run because once you fix it, you will know how to better isolate the problem and fix it if it happens again in the future
Thanks I feel a bit better now :)
I am designing some PCB so im just going to pull all the parts and swap them over to the new boards testing them as i go. Thanks for the input and I will hopfully put up a new video of it working in a couple weeks or so.
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
rebuilt the driver, the bridge, and the 12/5v pwr supply, all on a smaller separate boards which my not have been a good idea, but i plan on putting it in a small box.
*****Problem is with the driver again... I have gone over the board many many times and i found some unconnected pins and also some solder bridges, cleared all of them up ( i think) but still the 74ch chip gets extremely hot after a couple seconds. If i remove the chip nothing gets hot on the board, but it still fails to work. I have tried to replace the chip same result.
what would cause the chip to heat like that??**** FIXED
About to test it now
alright, so it didnt work... but i made some progress...
The driver makes and audible buzz when the sub cap isnt connected but stops when i plug one in. When the buzz is fed to the half bridge board it makes a cfl flicker and i can get a small static popping like spark but no arcs( the bridge is connected to 60v so it would be a lot brighter if it was switching)
The driver makes and audible buzz when the sub cap isnt connected but stops when i plug one in. When the buzz is fed to the half bridge board it makes a cfl flicker and i can get a small static popping like spark but no arcs( the bridge is connected to 60v so it would be a lot brighter if it was switching)
I had this happen in a recent build, it turned out that the primary was the issue. I encapsulated the primary in epoxy and wound it from the center outwards (as a means of securing it while winding) and I think I screwed up the phasing somehow. Try reversing the phasing of the primary (don't just flip it over, keep it still and switch which lead goes where). I had to remake the primary and then I had to switch the phasing and the issue was resolved. Also keep in mind that the leads to the primary should be as short as possible, leakage/stray inductance is your enemy.
Also, keep in mind that the UCC chips and 74HC14 tend to oscillate at VERY high frequencies (my boards do 6 to 9MHz!!!) when no feedback is applied, so never run the driver long without at least a minimum voltage being applied to the (half)bridge. I can run my bridge as low as 10Vac (14.4V DC) on the variac without the chips overheating, but a few seconds of running less than that where no feedback reaches the antenna and they get HOT fast.
I eventually switched my main SSTC over to using the 4046PLL chip as an always running oscillator so that the gate drive logic always has an in range signal regardless of feedback. I got real tired of blowing $4 chips because I was too slow at turning on/up the variac. The downside is that you have to fine tune the 4046 to the resonant frequency of your secondary, which is damn near impossible without a scope.
Registered Member #3114
Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608
Update:
I got the driver board oscillate, I think... By that I mean that I can hear an audible click that I can vary with the 10k pot's. But know I am having trouble with the bridge switching on. There is power in the caps but the board is not switching on even while it is reviving the signal from the ucc chips, I had this problem.before and it turned out it was one of my gate resistors but this time its a different problem.
The bridge is made if all new parts and hasnt been used until now so I can't imagine a blew any parts.
What would stop the bridge from turning on ? Does the GDT have polarity as far and the ucc chips go?
This site is powered by e107, which is released under the GNU GPL License. All work on this site, except where otherwise noted, is licensed under a Creative Commons Attribution-ShareAlike 2.5 License. By submitting any information to this site, you agree that anything submitted will be so licensed. Please read our Disclaimer and Policies page for information on your rights and responsibilities regarding this site.
SSTC 5 troubleshooting
