Help With Elec Please !

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Chester

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Mar 28, 2010
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74MKIIA

I was at this startup stage a few weeks ago, went to put the tank on, seen it was full of rust and have been dealing with that for the last couple weeks, now back to turnkey.
I'll be painfully detailing with what happened next just so not to leave anything out.

-put battery in, hooked up posts, turned key, nothing.
-notice in complete shock and dismay, cables are on backward, after all this work !
- beat oneself up awhile, then put leads on correctly.
-turn key, red charge indicator light comes on, one more click, headlight comes on.
-very exciting, do it again, just to see for the first time in over a decade.
-turn key off, ready to hoist bike out of the basement.
-about 1 hour later, try key, red indicator light comes on for 1 sec then fades out, try again, no light at all.
-about 1 min later...try key. red light comes on for 1 sec, fades.
-hoping it's just a battery problem, even though it was fully charged, decide to trickle charge aagain over night just to make sure.
-this morning, take fully charged battery , turn key....same thing.

All along Ive been wondering why the fuse didn't blow, after the initial wire cross. I'm pretty sure it's the original fuse because the writing on it is so worn, I can't see the amps.
How many amp fuse it it supposed to be?
I'd really appreciate some of your gents thoughts on this. Thank you.
 
When the light comes on then fades away is the battery hooked up to the charger? If so, it might be going out because the voltage is high enough to cause the assimilator to shut the light down. Have you tried starting the bike? Are you running stock or has anything been modernized?
 
No rvich.....I didn't have a charger on it.
I didn't try starting it either cuz it's still on the platform that i have to lower it from.

Everything is stock.

It's been so long.....but I assumed the red light stayed on until the bike was running?

I've gone to pick up another fuse holder and fuse.

There was a fellow there that could read trhe old fuse ( 35 amp). Seems the biggest glass fuse I could find there was a 30 amp.
Do you think it's OK to use a 30?
 
Chester said:
put battery in, hooked up posts,
Click to expand...

Fuse should have blown instantly at that point.


Chester said:
try key, red indicator light comes on for 1 sec then fades out
Click to expand...

That could be the 2MC capacitor discharging when the ignition is switched on. However that normally happens only when the 2MC is charged and the battery has been disconnected?

Chester said:
All along Ive been wondering why the fuse didn't blow, after the initial wire cross. I'm pretty sure it's the original fuse because the writing on it is so worn, I can't see the amps.
How many amp fuse it it supposed to be?
Click to expand...

The original 1.25" glass fuses were the old British blow rating of 35A, and that's equivalent to a 17.5A continuous fuse, the nearest modern equivalent fuses are either 15A or 20A. Do not use a 30A continuous fuse

Help With Elec Please !
 
Your avatar doesn't say what country your in and correct me if I'm wrong but I think British fuse rating is differant than American. I think a British 30 AMP is close to a American 17 AMP & I was told to use US. 15 I think. Maybe 20, I would have to go check but you may want to ask a more electricly knowageable member.
 
Chester said:
No rvich.....I didn't have a charger on it.
I didn't try starting it either cuz it's still on the platform that i have to lower it from.

Everything is stock.

It's been so long.....but I assumed the red light stayed on until the bike was running?

I've gone to pick up another fuse holder and fuse.

There was a fellow there that could read trhe old fuse ( 35 amp). Seems the biggest glass fuse I could find there was a 30 amp.
Do you think it's OK to use a 30?
Click to expand...

You might try doing a search at the start of the Forum for "Warning Light Assimilator" there is a post there that mentions the unit doesn't work with Neg earth, so it might have been zapped when you crossed the wires. Does the Assimilator measure AC or DC ? I've not got access to a wiring diagram at the moment but I thought it took a feed straight from the alternator and measured its output and providing it was enough put the light out?
 
You guys are correct on the 15- 20 amp thing.

Even visually, the band in this 35 amp fuse is huge compared to the original.
Gotta go change that right off.
 
Check the fuse holder carefully if it's the old in-line type.
 
Yes L.A.B. it is the old inline one and I replaced it about 10 minutes ago with a new one and I'm all lit up, just like I ought to be.

Current indicator, lights, horn. I really dodged a bullet there.

Perhaps I should have tried something like that before I panicked , but I really wasn't sure if I'd blown or fried something.

As well I wouldn't have known about the Brit 35 amp to American 15-20 amp, and might have incured some damage on something else,
because I did put that fat 35 in.

Thanks much ! ! ! ! !
 
A Guy I know ran a wrong foot Bonneville as regular transport . He put in a new fuse every two weeks , and never had one blow . He mentioned the term ' Vibration ' .
 
The warning light assimlator works something like a relay with switch contacts in the normally closed position. However, instead of using a coil of wire to pull the switch contacts open, it uses a tension wire that holds the switch contacts closed so that when the wire gets hot from the electrical current (from the alternator), the wire expands allowing the switch contacts to open. It really does not make sense that the warning light assimlator would be the problem because the switch contacts are either open or closed, but I guess anything could happen. One way to check for sure though is to disconnect the white and brown wire at the warning light assimlator and using a clip lead, connect that white and brown wire directly to ground. Now when the key switch is turned on, the light should illuminate and remain on. However, if the light still fades you know that the warning light assimlator is not the culprit, it is simply something wrong with the lighting circuit.

The warning light assimlator is not polarity sensitive so it would not have been damaged due to reversing the battery connection. However, the zener diode, the rectifier and the 2MC capacitor are polarity sensitive. There is a good chance that the zener diode and the rectifier are ruined. The capacitor may be ok, but should be checked along with the rest.

Zener diodes, as well as any semi-conductors (transistors, etc) are easily damaged if connected incorrectly and it takes just a brief moment to completely destroy them. The fuse in the circuit could never blow before the damage is done.
 
PeterJoe said:
The warning light assimlator works something like a relay with switch contacts in the normally closed position. However, instead of using a coil of wire to pull the switch contacts open, it uses a tension wire that holds the switch contacts closed so that when the wire gets hot from the electrical current (from the alternator), the wire expands allowing the switch contacts to open. It really does not make sense that the warning light assimlator would be the problem because the switch contacts are either open or closed, but I guess anything could happen. One way to check for sure though is to disconnect the white and brown wire at the warning light assimlator and using a clip lead, connect that white and brown wire directly to ground. Now when the key switch is turned on, the light should illuminate and remain on. However, if the light still fades you know that the warning light assimlator is not the culprit, it is simply something wrong with the lighting circuit.

The warning light assimlator is not polarity sensitive so it would not have been damaged due to reversing the battery connection. However, the zener diode, the rectifier and the 2MC capacitor are polarity sensitive. There is a good chance that the zener diode and the rectifier are ruined. The capacitor may be ok, but should be checked along with the rest.

Zener diodes, as well as any semi-conductors (transistors, etc) are easily damaged if connected incorrectly and it takes just a brief moment to completely destroy them. The fuse in the circuit could never blow before the damage is done.
Click to expand...

But I think Chester has already found the problem, PeterJoe?
Seems it was just a dud fuse holder (which may have saved the day when the battery was connected wrongly?).
 
L.A.B. said:
But I think Chester has already found the problem, PeterJoe?
Seems it was just a dud fuse holder (which may have saved the day when the battery was connected wrongly?).
Click to expand...
[/quote]

One must question the health of the Zener diode and rectifier assembly now. At least some basic resistance checks forward/reverse would be in order.
 
Here is the fuse conversion chart from Bussman Co.

English Type - American Standard Replacement

50 amp = AGC 30

35 amp = AGC 25

30 amp = AGC 20

25 amp = AGC 15

20 amp = AGC 10

10 amp = AGC 7 1/2

5 amp = AGC 3
 
beefco said:
35 amp = AGC 25
Click to expand...

However, I think the majority would consider 15A - 20A a more suitable alternative.

http://www.groups.tr-register.co.uk/nen ... 20BUSS.pdf
The complete rating for the specified 35 amp Lucas fuse is…
“17 AMPS CONTINUOUS / 35 AMP SURGE”
Early British fuses were simply marked with the quick-blow rating, but later fuses are given two
ratings in an effort to minimize the confusion. For instance, the 35 Amp fuse is often marked as
“17 continuous/ 35 blow”, or simply 17/35. In that case, use the lower “continuous” rating as the
one to which you try to match an American BUSS fuse rating.


British Lucas Fuse ~ American BUSS Fuse
Fast Blow Dual Rating ~ Continuous (AGC)
50 amp 25/50 amp ~ 25 amp
35 amp 17/35 amp ~ 17 amp
30 amp 15/30 amp ~ 15 amp
25 amp 12/25 amp ~ 12 amp
20 amp 10/20 amp ~ 10 amp
15 amp 7.5/15 amp ~ 8 amp
10 amp 5 /10 amp ~ 5 amp
5 amp 2.5 / 5 amp ~3 amp
2 amp 1 / 2 amp ~ 1 amp
Click to expand...

http://www.drooartz.com/index.php?page=29&printview=1
 
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