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General >> Rally >> alpha computer glitch fix
https://www.mlrc.ca/cgi-bin/yabb/YaBB.pl?num=1108736807

Message started by big_Ian on 02/18/5 at 09:26:47

Title: alpha computer glitch fix
Post by big_Ian on 02/18/5 at 09:26:47

I have been a frustrated apha owner for a few years.The problem is when you switch the aux lights off the computer glitches ,odo goes to outer space ,factor goes down the drain ect. >:(
the first fix suggested was" make sure plgs are secure ,separate wires to battery terminals tight..bla bla bla.... ???
second fix
separate 12 v cordless drill battery inline to act like a big capacator/filter to absorb voltage spikes...still no dice

Final and now working fix
attach a diode across the coil terminals of your relays!!!!
It works (white stripe to positive side)
what is happening is when you de energize the coil of the relay the collapsing field creates a voltage spike back through ground and upsets the computer.The diode acts as a gate and keeps that from happening.
now I DON'T HAVE TO SMASH THE ALPHA WITH A HAMMER AND BUY A TERRA TRIP weeeee haaaa ;D
Ian
Clearwaterdesign

Title: Re: alpha computer glitch fix
Post by RyanHuber on 02/18/5 at 11:17:30

Ian, John V and I last year had a similar issue with his Alfa before OWR last year as well. Bryn Epp suggested something that has worked ever since, with John's car anyways. You need to wrap the power lead to the odo around a ferrite core. Most electronics places should have what you're looking for. It looks like a little cube, with a hole through the middle, that splits down the middle and will open up. You wrap your power lead around the outside and through the middle a few times, then close it back up. It has the effect of dampening out any spikes in the power.

Title: Re: alpha computer glitch fix
Post by dtompsett on 02/23/5 at 01:07:10

Ya, i've got a little capacitor wired directly to the alfa wiring terminal between the +ve and -ve connections. That has seemed to eliminate the problems I had with the computer randomly resetting, and the computer loosing information while running (screen goes all garbled, need to force a hard reset to make it work properly again).

Now, the only problem I have is that the ALFA interferes with the 2m mobile radio.... with the alfa on, and the radio on, I get interference on basically all stations when the car is moving (alfa is detecting the VSS). Of course.... when the alfa is off... I get interference at 145.000, 145.990 - 146.000, and 146.650 - 146-670....... interfence generated by the alternator/ignition system I presume, since the radio works like a charm when the car is shut off.

Will that ferrite core trick work for the radio? Wrap the power leads around the core. I seem to recall something in the RAC study guide about eliminating radio interference by wrapping cords around ferrite cores.

Title: Re: alpha computer glitch fix
Post by Craig_Hamm on 02/26/5 at 01:32:24

I recommend twisting the power leads to your radio before you route the harness to the radio. Otherwise the two unshielded wires act as an open magnetic loop (e.g. antenna) and will pick up loads of crud under the hood. This is good advice. Try to route the power leads away from high voltage sources if possible, like ignition or coil wires. Twist them well, it will take a little more wire, but worth it to knock down this magnetic coupling (the magnetic part of the radiated electromagentics).

Ferrite cores are inductive isolation or filtering (magnetic related), and capacitors are umm, capacitive filtering (charge related). But, I've haven't dabbled in electrics world for a long time and can't say much more than that.

Btw, if you have crappy cables under the hood for stuff like your ignition (e.g. bad coil wire) it will radiate pulses into your odo signals, and your odo will be off. I learned this the hard way when re-measuring a rally section once. So, try to keep all your OTHER wires and connections in good order or it'll turn your lovely Alpha into an overpriced random number generator!

You have a ham ticket? Cool. Oi, turn off the radio when rallying. You might hear something. .. . I think I'll have to start planting false info into the Lanark comms! Too many clever arse hams on the teams nowadays.

Btw, Ian, those prizes offered at OWR sure sounded great (and not cheap). Thanks for supporting the grassroots!!

Title: Re: alpha computer glitch fix
Post by dtompsett on 02/27/5 at 23:13:23

Well, the wiring isn't hard to access, so maybe someday when it's warm out I will try twisting it.

Ya, I left the radio off for most of OWR... I turned it on for a few minutes during leg b or c..... just after the checkpoint on upper old hastings... I hear radio chatter in the checkpoint vehicle, and wondered what it was... so i turned mine on.... something about they had solved the problem with the incorrect accumulated distances in the notes.

Title: Re: alpha computer glitch fix
Post by brynepp on 03/05/5 at 19:51:42

Sounds like I need to write an article on cleaning up power lines in cars.

^%$# I opened my mounth!
Now, were's that word processer :)

Looking at all the responses It looks like all the types of noise fixes have been used here. Now to explain them in that article.