Re: (ET) new relay in - now no reverse

[David C Robie <mycroftxx1 juno com>]

I wouldn't do that temporary fix.  You may forget to wait some day.

Dave
Weymouth MA


On Sat, 5 Aug 2006 13:08:37 -0400 (EDT) Michael S Briggs
<msbriggs alberti unh edu> writes:
> 
> To answer my own question about jumpering pins 8 and 9 on card 1 
> together, 
> and what card 1 actually DOES as far as the reverse relay control - 
> from 
> the card, it looks like it's a time delay circuit, so that if you 
> flip 
> from forward to reverse (or vice versa) too quickly, while the motor 
> is 
> still spinning one way, you don't suddenly reverse the field to 
> point in 
> the opposite direction. Is that correct? So, the reason I shouldn't 
> just 
> jumper 8 and 9 together is so I don't go and reverse the field too 
> quick, 
> which would probably give me a big induced current in the field 
> winding, 
> presumably frying a connection somewhere - probably on the relay.
>       Seems like I could do that as a temporary fix (if I need to 
> wait 
> for some part to arrive so I can fix card 1), just making sure I 
> give 
> plenty of time between going from forward and reverse, to avoid 
> frying 
> relays left and right.
>       I'll check though to see if I can determine what part on 
> card 1 
> fried, to see if I can get it working without jumpering across those 
> 
> terminals (we have gobs of resistors and capacitors at work, so if 
> that's 
> all it is, I can "borrow" a 3 cent resistor or cap to fix it).
> 
> Mike
> 
> -- 
> 
> --------------------------------------------------------------
> Michael S. Briggs
> UNH Physics Department
> (603) 862-2828
> ---------------------------------------------------------------
> 
> On Sat, 5 Aug 2006, Michael S Briggs wrote:
> 
> >
> > 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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