Isolation transformer source
in [Repair]
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From: JW on 12 Jun 2010 06:56 On Fri, 11 Jun 2010 10:30:56 +1000 "Phil Allison" <phil_a(a)tpg.com.au> wrote in Message id: <87dee7Fdj9U1(a)mid.individual.net>: > >"JW" > >> Can anyone recommend a good isolation transformer for sale on-line? > >** What kind ?? > >There are two: > >1. Galvanic isolation - for use on a service bench. Galvanic. Thanks - didn't realize there are different kinds. Don't want to kill myself!
From: JW on 12 Jun 2010 07:01 On Fri, 11 Jun 2010 08:24:36 -0500 Chuck <ch(a)deja.net> wrote in Message id: <r7e416tt40mloqh91evegbjo9eb2qllqjk(a)4ax.com>: >On Thu, 10 Jun 2010 09:44:12 -0400, JW <none(a)dev.null> wrote: > >>Can anyone recommend a good isolation transformer for sale on-line? >>Need one that will handle 5 amps or so at 120VAC, and have a standard AC >>plug at the outlet. Prefer one for less than $100 or so, unless that seems >>unreasonable. Found one at Mouser for $114 but that's only good for 1.25A. >>Getting lots of irrelevant hits on google... >> >>Thanks. > > >MCM Electronics has one. Chuck Thanks Chuck. Looking at these for the moment: http://www.mcmelectronics.com/product/TRIPP-LITE--POWER-PROTECTION--IS500-/28-10160 http://www.mcmelectronics.com/product/TENMA-72-1097-/72-1097 A bit more than I wanted to spend and a little less current capability, but those may be the breaks.
From: Dave Plowman (News) on 12 Jun 2010 07:00 In article <jqp6161lis3v93582a2p4q6g9212udvqpt(a)4ax.com>, JW <none(a)dev.null> wrote: > On Fri, 11 Jun 2010 10:30:56 +1000 "Phil Allison" <phil_a(a)tpg.com.au> > wrote in Message id: <87dee7Fdj9U1(a)mid.individual.net>: > > > >"JW" > > > >> Can anyone recommend a good isolation transformer for sale on-line? > > > >** What kind ?? > > > >There are two: > > > >1. Galvanic isolation - for use on a service bench. > Galvanic. Thanks - didn't realize there are different kinds. Don't want > to kill myself! It certainly seems to me stupid to have the same name for different devices like this. What is the point of an isolating transformer which doesn't isolate? -- *When a clock is hungry it goes back four seconds* Dave Plowman dave(a)davenoise.co.uk London SW To e-mail, change noise into sound.
From: PeterD on 12 Jun 2010 08:02 On Sat, 12 Jun 2010 06:53:47 -0400, JW <none(a)dev.null> wrote: >>... >Nice price. I'm working on a 1KW HP 6032A power supply (with outputs >unloaded in this case, so I don't need *too* much current capability) and >need to connect my scope to the hot side of a switching transformer - >specifically the source and drains on the output FETs. > >Service manual: (3MB) >http://www.home.agilent.com/agilent/redirector.jspx?action=ref&cname=AGILENT_EDITORIAL&ckey=1000000384-1%3Aepsg%3Aman&lc=eng&cc=US&nfr=-35687.384731 >Page 113 shows the schematic of the FET board. > >With an isolation transformer, I *think* I would connect the scopes GND >lead the source of Q1 and probe the it's gate to check the it, then move >the scopes GND lead to Q3's drain lead to check it's gate drive. > >Given that, would that Ebay transformer be the right choice, and do I need >to isolate (disconnect) the ground on the 6032A power supply under repair? > >Thanks. You need to make 100% sure your life insurance is fully paid up. <g>
From: tm on 12 Jun 2010 10:32
"JW" <none(a)dev.null> wrote in message news:0qo616dhg4nsgshqjsia9l39venjef4bt6(a)4ax.com... > > Nice price. I'm working on a 1KW HP 6032A power supply (with outputs > unloaded in this case, so I don't need *too* much current capability) and > need to connect my scope to the hot side of a switching transformer - > specifically the source and drains on the output FETs. > > Service manual: (3MB) > http://www.home.agilent.com/agilent/redirector.jspx?action=ref&cname=AGILENT_EDITORIAL&ckey=1000000384-1%3Aepsg%3Aman&lc=eng&cc=US&nfr=-35687.384731 > Page 113 shows the schematic of the FET board. > > With an isolation transformer, I *think* I would connect the scopes GND > lead the source of Q1 and probe the it's gate to check the it, then move > the scopes GND lead to Q3's drain lead to check it's gate drive. > > Given that, would that Ebay transformer be the right choice, and do I need > to isolate (disconnect) the ground on the 6032A power supply under repair? > > Thanks. This is a "bad idea". Better to use a differential input and two probes. Do you have a two channel scope with invert on channel 2? Tom |