Damn damn damn. Ok, it looks like I have a problem on card 1. With the speed lever in reverse (neutral), I get battery voltage at wire 41 (terminal 8) on card 1, but nothing on wire 39 (terminal 9) on card 1. So, card 1 ain't working properly. Hmmmm... could I for now just jumper them together? What exactly does card 1 DO as far as controlling the forward/reverse relay? It seems like it just passes battery voltage on to the relay - it comes into card 1 on wire 41, and goes out on wire 39. So, is there any real need to have it go through card 1? At any rate, unless someone says it's ok to jumper terminals 8 and 9 together (wait, didn't I just see someone say that? Or was that in the archives?), I'll try to find what part blew on card 1. Also need to determine WHY. Did card 1 fail, which then caused the new relay I put in to fail? Or, was the new relay bad to begin with, and due to it having some short across the coil, it caused a failure on card 1. Ah, the chicken or the egg.... :) I'm going to swap in one of the other relays. Mental note - but parts (such as replacement relays) from Harold, instead of cheap Chinese parts.... I guess I can also use this opportunity to put in that shiny new capacitor for the charger. :)
I wonder if I can mow the entire yard with only forward speeds....
Thanks,
Mike
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Michael S. Briggs
UNH Physics Department
(603) 862-2828
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On Sat, 5 Aug 2006, Michael S Briggs wrote:
On Sat, 5 Aug 2006, RJ Kanary wrote: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.Ah, I see what you're getting at. That doesn't seem to be the case here though - I found that I am getting voltage coming off of wire 41 at card 1 when moving the switch to reverse, but no voltage at the relay itself. Still need to find where it's disappearing between there, but in the mean time, I discovered something else. I decided to test the resistance of the coil on the relay (the powered connections), and it's zero. Checked two identical new relays (these are the $4.50 or so 3PDT 36VDC relays from the Surplus Electronics place someone else mentioned here), and across the coil they measure a bit over 1 kiliohm. So, either the relay was bad before I put it in, or there was a failure in the coil when after putting it in. Having a short there likely caused something else to fail, by getting too much current through the relay, and may be why I'm not seeing any voltage at the relay anymore. So, I'll backtrack between the relay and wire 41s connection to card 1, to find the problem connection. The bigger question though now is whether the relay was bad before putting it in (should have tested it - damn), or if it failed after putting it in. And if the latter, why. I'm not familiar with the internals of relays - I know they work based on a solenoid switch, but I'm not sure if it matters with relays which way the current flows through the solenoid (I know you'll get a B field in opposite directions depending on the current flow, but since I'm not sure how exactly it operates the switch, I don't know if that matters). So, if I had wired the power connections up backwards, could that have fried the relay? I wouldn't think so, but.... (I did check and see that it has the powered connections labelled A and B, as did the old relay, and I connected the new one the same way as the old one, so I wouldn't think this should be an issue though.....).Now to find what got fried by having a short across the relay.... MikeIf 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 reverseRJ, 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, {WireAlrighty. 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 reverseSo 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 aspin 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/reverserelay wrong. I checked, and nope, it's fine. The problem is that the relayisn'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 thefailures that I've had - while mowing last week, it stopped running - thecontrol 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 speedcontrol lever to reverse, I thought I heard the sound of something blowing- wasn't sure though if it was just the reverse microswitch clicking, orif something did in fact blow. It looks like control of the reverse relaygoes 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 justloose, or if something did in fact blow). I should be able to troubleshootit 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 oppositedirection - 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