Attempt to repair/jump CMU from 84 to get the high beam

[Arxvz1200]

Hi,

My high beam from 84 venture was lost and the fault is the computer (thank you all for helping me to find it).

I thought I start new thread for this rescue mission.

 

 

 

Removing the dashboard and computer is quite easy. There is a corner broken off and burned. I don't know if component has given up and burned or has the corner broken off and cause the component to burn.

 

Anyway I'm very unexperienced in circuit boards and soldering. People with HID/LED have jumped that part so it will not cause warning.

great info getting the computer out

http://www.venturerider.org/forum/sh...Display-Repair

 

Jumping CMU

http://www.venturerider.org/forum/showthread.php?92274-How-do-you-quot-Jumper-the-CMU-quot-for-LED-s-bulbs-to-prevent-the-warning-light-coming-on&highlight=jumpers

 

What do you think can the computer be rescued ?

Anssi

[bongobobny]

Yes, the PC board can probably be rescued, but if you are not familiar with a soldering iron then get someone who is to help you out there.

 

I am assuming from your previous text that you were going to jumper the existing magnetic reed switch anyways, so that makes the task a little easier. What you want to do is first remove the burnt up reed switch and electromagnet assembly, and then clean up as much of the board as possible. Then, using some sort of compatible epoxy or adhesive, reattach your broken piece to the main board. It looks like only one actual circuit trace was broken so that should be easy to jumper. What has to happen is the green protective coating on each side of the break has to be removed by scraping or sanding until the copper trace is clean and visible. Then, using a suitable piece of wire simply solder the jumper to each side of the break. Finish off the repair by coating it with nail polish or paint to insulate the repair. You should be good to go then...

[Arxvz1200]

I was comparing the board to the working one. There are more broken connections than I expected. Maybe beyond repair for me ?

 

in The magnetic reed switch, is the copper winding the high beam and the other contact are for warning light ?

if the current in high beam is too low then the switch turns opens or closes the other ?

 

 

 

 

[bongobobny]

Yes, that is how it works. The coil is hooked up to the high beam circuit so when the high beam is on current flows through the coil producing or making an electromagnet. This causes the two contacts of the reed switch to make contact and turn on the high beam dash light.

 

You should be able to fix both sides of the board with wire and solder as I previously mentioned. On the solder side, just wrap the wire around where the coil and switch lead come through the board and use lots of solder. On the trace side just strip the green insulation on each side of the crack and bridge it with a piece of wire and you should be good to go. Of course, I have to ask, where are you going to come up with a new reed switch and coil assembly?? Your old one looked like toast...

 

Of course, you could just replace the board and get on with life!

[Flyinfool]

Pretty simple, You just need 2 jumpers.

 

Jumpers are shown in red in the attached pic.

 

First jumper can be any small insulated wire. It goes from the pad by the D20 mark to the copper area that has the CN1 marking on it. This wire will make the CMU stop telling you that the hi beam bulb is out.

 

The other jumper just goes across the 2 wide circuit runs, this one needs to be a heavier gauge of wire since it will be carrying the full current of the high beam. This jumper is the one that will make the Hi beam be functional.

 

 

 

 

This is just a WAG on my part. I wonder if someone had put in one of those really HIGH wattage bulbs to try to get more light, I know You can get bulbs up over 100W, This much power could melt things, That coil is likely the thinnest wire in the circuit so it acted as the fuse. Check you headlight fuse to be sure it was not jumpered or replaced with a higher amp one. Something made that coil burn up, about the only thing that can burn up a coil of wire is sustained high amps. also check the wiring to be sure none of it is damaged where that Hi Beam wire might be able to short to ground. You need to do some looking to see if you can find a reason that coil burned up. Next time it might not be an easy, and cheap fix.

 

 

To get the screw mounting point back just epoxy that corner back on and maybe add bit of something NON CONDUCTIVE (like a Popsicle stick) over the crack for support.

Edited July 23, 2018 by Flyinfool

[Arxvz1200]

Hi,

So here's what I did. I did remove insulation, the jumper wire is not connecting any other component (it's close and in the pic it looks like it's connected to one above).

 

Isn't pretty, but selfmade

I have not soldered anything for 30 yrs.

 

Dunno if it works, might take a while before I'm taking the dash out. I'll be sure to update when I do

[Flyinfool]

The jumper wire is much heavier gauge than needed and it looks like cold solder joints. Cold solder joints will fail quickly with any shock or vibration.

For the other connection did you just bridge solder across or is there some wire in there to?

 

To do the jumper, Precoat the circuit board connection points with solder and a non corrosive flux, this is called tinning. (Plumbing flux is acid based and the acid will eat away at your joints.) Do not rely on just the flux core of the solder. Then twist the strands of the wire tight and using flux tin the ends of the wire. now when you solder the wire to the board you will need to ad very little if any additional solder to the joint. NEVER melt the solder with the tip of the iron. ALWAYS heat the part with the iron until the part is hot enough to melt the solder. the solder should be bright, smooth and shiny if it is a good joint.