[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: (ET) new relay in - now no reverse
- or smoke of a different type - The issue of blood from all electronic
-electrical
Dave
Weymouth MA
On Sat, 5 Aug 2006 11:24:40 -0400 "RJ Kanary" <rjkanary nauticom net>
writes:
> Because high resistance in a circuit , coupled with a high
>
> impedance sand based meter will 'tell' you that voltage is
> there........but
> not enough current flow to do any work. Not until a load is present
> will you
> see what's really up.
> If you are working on more delicate things, such as
> computers, a
> high impedance tool is a must.
> Draw too much current from a circuit, the minimal trouble
> you'll
> have is a low reading that is in error, since the meter is sinking
> more
> power that the device can source. The maximum grief you can have is
> letting
> the smoke out of some very important pieces. <VBF>
> Don't get me wrong. A Fluke 87® sits right next to my Simpson
> 260® on
> the tool cart. Both have their strengths and weaknesses. The trick
> is
> learning how to use this knowledge to best arm you for the battle at
> hand.
> And yes, the voltages that you are observing should be within
> 5 or 10%
> of what system voltage is.
> Here's hoping that the odor of Ersin® Multicore solder is NOT
> filling
> your nostrils this afternoon. :)
>
> ----- Original Message -----
> From: "Michael S Briggs" <msbriggs alberti unh edu>
> To: "RJ Kanary" <rjkanary nauticom net>
> Cc: <elec-trak cosmos phy tufts edu>
> Sent: Saturday, August 05, 2006 10:56 AM
> Subject: Re: (ET) new relay in - now no reverse
>
>
> >
> >
> > RJ,
> >
> > On Fri, 4 Aug 2006, RJ Kanary wrote:
> >
> >> Prove out all the voltages that SHOULD be present with an
> ANALOG
> >> VOM.High impedance sand based DMMs will lie to you especially at
> these
> >> voltages.
> >
> > I don't see why a DMM should be inaccurate on voltage. Don't you
> *want* a
> > voltmeter to have high (very very high) impedance? Otherwise when
> you
> > connect it in parallel with some circuit element, the combined
> parallel
> > resistance of the voltmeter and the element you're measuring
> voltage
> > across can drop some, so the voltage you would read wouldn't be
> the
> > voltage it normally sees. So, I don't see why you would want a
> lower
> > impedance on your meter.
> >
> >> Verify that voltage AND current is available at Pad 8 {Wire
> 41} of
> >> Card 1 when Reverse is selected. If this proves out move to Pad
> 9, {Wire
> >
> > Alrighty. I'm assuming it should have the full 36V (or 38V, or
> whatever
> > the pack is putting out) at those points.
> >
> >> 38}. If voltage and current is present here, now you can suspect
> a wiring
> >> error at the other relay terminals.If voltage and current is NOT
> present
> >> here, you are about to embark on one of the finer adventures of
> owning
> >> and repairing an AA model E-15, repairing Card 1. :(
> >
> > D'oh. I'll check it in an hour or two - need to finish making some
>
> > biodiesel for our cars and furnace first. Given that I thought I
> heard a
> > "pop" noise when I first put it in reverse after putting in the
> new relay,
> > I'm unfortunately thinking it's not going to be a simple wiring
> issue.
> > :( But, if it's just a case of a blown resistor or cap on card 1,
> that
> > shouldn't be too bad - I've done a fair amount of electronics work
> in the
> > past. Well, it shouldn't be bad if it's obvious which element
> blew. :)
> > Chasing down a bad circuit element can be a pain in the tuckus.
> >
> > Thanks,
> > Mike
> >
> >
> >>
> >> ----- Original Message ----- From: "Michael S Briggs"
> >> <msbriggs alberti unh edu>
> >> To: <elec-trak cosmos phy tufts edu>
> >> Sent: Friday, August 04, 2006 9:35 PM
> >> Subject: (ET) new relay in - now no reverse
> >>
> >>
> >>>
> >>> So I finally had time to put in a new relay in place of the
> blown
> >>> forward/reverse relay. Forward works fine now - even took it out
> for a
> >>> spin around the neighborhood. When I then went to back it into
> the
> >>> garage,
> >>> I discovered that when I try to go in reverse, it goes forward.
> D'oh!
> >>> My first thought was that I had hooked up the
> forward/reverse
> >>> relay wrong. I checked, and nope, it's fine. The problem is that
> the
> >>> relay
> >>> isn't firing when I move the switch to the reverse-neutral side.
> I hear
> >>> the reverse microswitch click, but the relay doesn't move.
> Checked the
> >>> power connections on the relay, and it doesn't seem to be
> getting any
> >>> power when I move the speed lever to reverse.
> >>> Now, I suppose I could have just knocked something loose while
> >>> fiddling with everything in there, but I'm wondering if there
> could be
> >>> some greater problem going on that I'm overlooking (considering
> all the
> >>> failures that I've had - while mowing last week, it stopped
> running -
> >>> the
> >>> control fuse had blown, and took out the fuse block in the
> process.
> >>> Put in an inline fuseholder in place of the fuse block, with a
> fresh
> >>> fuse,
> >>> and found that I couldn't go forward due to a blown
> forward/reverse
> >>> relay.
> >>> Put in a new relay, and now the relay isn't getting voltage to
> fire. It
> >>> seems like each time I fix one thing, something else breaks).
> >>> After putting in the new relay, the first time I moved the
> speed
> >>> control lever to reverse, I thought I heard the sound of
> something
> >>> blowing
> >>> - wasn't sure though if it was just the reverse microswitch
> clicking, or
> >>> if something did in fact blow. It looks like control of the
> reverse
> >>> relay
> >>> goes through card#1 somewhere (still need to look over the
> schematics to
> >>> figure out which "port(s)" on card 1, so I can see if something
> is just
> >>> loose, or if something did in fact blow). I should be able to
> >>> troubleshoot
> >>> it ok, but what I'm concerned about is if there might be some
> greater
> >>> problem underlying these little annoying problems. There have
> just been
> >>> too many failures one after another for it to just be a
> coincidence, I
> >>> think.
> >>> Actually - if I had wired the power connections to the reverse
> >>> relay backwards, what would that do? From looking at the relay,
> I assume
> >>> it just uses a current through a solenoid to control a switch.
> If the
> >>> current goes the wrong way, the B field would point in the
> opposite
> >>> direction - but since I'm not sure exactly how it controls the
> switch,
> >>> I'm
> >>> not sure if that would be a problem or not, or if it could blow
> >>> something.
> >>> So, any tips anyone can offer (again) would be appreciated.
> >>>
> >>> Thanks,
> >>> Mike
> >>>
> >>> --
> >>>
> >>> --------------------------------------------------------------
> >>> Michael S. Briggs
> >>> UNH Physics Department
> >>> (603) 862-2828
> >>> ---------------------------------------------------------------
> >>>
> >>> _______________________________________________
> >>> Elec-trak mailing list
> >>> Elec-trak cosmos phy tufts edu
> >>> https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
> >>>
> >>
> >
>
>
> _______________________________________________
> Elec-trak mailing list
> Elec-trak cosmos phy tufts edu
> https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
>