EMCO HV converter not being switched
EMCO HV converter not being switched
(OP)
HI folks,
Because of space requirements I changed out an existing PSU supplying an FET push-pull driver for a transducer to a Q-Series EMCO HV DC converter (Q05-5). The component is operating correctly but the push-pull network doesn't seem to be switching. My push-pull netowrk uses Int'l Rect. N & P FETs rated for 150v and 200v respectively. The DC conv. output is stable at 140v. What is the problem? I just changed the source voltage to the PP network.
http://www.emcohighvoltage.com/
Thanks in advance
Because of space requirements I changed out an existing PSU supplying an FET push-pull driver for a transducer to a Q-Series EMCO HV DC converter (Q05-5). The component is operating correctly but the push-pull network doesn't seem to be switching. My push-pull netowrk uses Int'l Rect. N & P FETs rated for 150v and 200v respectively. The DC conv. output is stable at 140v. What is the problem? I just changed the source voltage to the PP network.
http://www.emcohighvoltage.com/
Thanks in advance





RE: EMCO HV converter not being switched
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: EMCO HV converter not being switched
RE: EMCO HV converter not being switched
If this system worked fine before you changed supplies have you hooked up the grounds correctly between the 'new supply' and your existing hardware?
You description sounds like you flat have no power going to the FETs.
What does the o-scope show for the FET gate signals?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: EMCO HV converter not being switched
140V output on a 150V FET is marginal - add in a di/dt induced voltage spike and you'll exceed the switch rating. Even if it is working now doesn't guarantee it will last. FET's with a 600V or 800V rating are a commodity item because they're used in mains-fed SMPS designs all over the world, so they don't command much premium in price.
Is this a pure push-pull design or is there some dead time between the two switches? DC bus shoot-through is the usual outcome of pure push-pull.
----------------------------------
I don't suffer from insanity. I enjoy it...
RE: EMCO HV converter not being switched
The output you are stating GoKid is something you might see capacitively coupled through dead FETs.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: EMCO HV converter not being switched
I'm voting for fried FET on this one...
Dan - Owner
http://www.Hi-TecDesigns.com
RE: EMCO HV converter not being switched
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: EMCO HV converter not being switched
Dan - Owner
http://www.Hi-TecDesigns.com
RE: EMCO HV converter not being switched
I thought you made automotive gizmos Dan? That sounds a little excessive for a dash light controller. Have you ever heard of a 555?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: EMCO HV converter not being switched
Besides, I don't need no stinkin' 555s around here... I use the all-powerful PIC :D Twice the power at twice the price!
I'm curious to see the OP's comments once he logs back on...
Dan - Owner
http://www.Hi-TecDesigns.com
RE: EMCO HV converter not being switched
I had a National Semi emulator the size of a place mat that was for their 800 series 4bit processors. I designed a temp logger that you could just plug into any printer with a parallel port and would spontaneously print out a formatted sheet of the temp recordings. We were leasing the emulator. One of our techs borrowed the lab supply that was required to run it. (5V)
Without ever telling me, he brought it back, reinstalled it and left.
I came in later and fired it up. It smoked! The tech had set it to 15V for his task.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: EMCO HV converter not being switched
So here I come, be-boppin' along in the lab getting ready to test a board. The plug slides right in, I think nothing of it, and crank 'er up. Why don't I have video? <sniff sniff> Is something burning? Uh-ohhhhhhh.
The head cheese heard about it, walked in and looked it over, said a few things that would make a sailor blush, then started looking for someone to blame. The second cheese in command looked at me, chastised me for plugging it in backwards and claimed it would have to have been forced in to get it in backwards. "Here, I'll show you!", he says, and grabs the plug... as it slid right in backwards with no resistance ;)
The plug was replaced with the next parts order, and for the several days until the new plug came in there was white-out on pin 1
Dan - Owner
http://www.Hi-TecDesigns.com