Author Topic: Voltage loss at Ignition switch  (Read 7679 times)

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Offline trebuchetxlt

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Voltage loss at Ignition switch
« on: April 13, 2014, 01:54:18 PM »
I was checking the voltage at my Ignition switch, '75 CB550, and noticed that although the voltage reading at the Red wire into the switch was at 12.8 Volts it was only reading 11.8 Volts at the Black wire coming out of the switch, the reading was taken at the connector on the switch side. I thought it was probably due to resistance in the switch, it was the bikes original, so I tried it with another switch I had, admittedly it is one of the Emco aftermarket deals, but, it's not had much use, and got exactly the same reading.
It seems strange that 2 different switches would give the same results, any thoughts?
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Offline Don R

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Re: Voltage loss at Ignition switch
« Reply #1 on: April 13, 2014, 10:20:13 PM »
Hondaman says that happens, that's why he makes a relay to help with that problem. It's been discussed here before. Try searching voltage drop maybe.
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Offline Deltarider

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Re: Voltage loss at Ignition switch
« Reply #2 on: April 14, 2014, 01:34:04 AM »
I'd say it's not abnormal.
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Offline Bodi

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Re: Voltage loss at Ignition switch
« Reply #3 on: April 14, 2014, 07:11:17 AM »
I don't think that should be considered normal. One volt drop at the switch with 5 amps (a low guess of actual current) means 5W of heat  produced at the switch contact. That is a lot of heat for a small area - look at a 5W resistor, it's pretty big and they still get stinking hot in free air with 5 actual Watts dissipating. It's enough to melt the plastic around an enclosed switch contact.
I would accept a few tenths of a volt but 1V seems definitely high here.

Offline Deltarider

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Re: Voltage loss at Ignition switch
« Reply #4 on: April 14, 2014, 07:27:53 AM »
With all respect Bodi but I'm afraid you've got it all mixed up. Can't make sense of your Watts. It's about Ohms law that measures in: volts, ampères and Ohms.
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Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #5 on: April 14, 2014, 11:08:03 AM »
The switch normally carries about 10 amps through it.  A one volt drop indicates a resistance of 0.1 ohms using ohm's law, or using watt's law 10 watts dissipation (or 10 watts wasted of alternator output.)

Bodi is correct.  A one volt drop through the ignition switch is NOT normal, and in my opinion, unacceptable.  All end devices will operate as starved and crippled receiving less voltage than available, and the voltage regulator will be unable to determine the correct voltage state of the battery.

The stock ignition switch can usually be rebuilt if the internal bits that hold the contacts and springs in proper position aren't melted too badly.
It does take some prowess and care to do without losing essential internal bits.
« Last Edit: April 14, 2014, 11:10:01 AM by TwoTired »
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Offline Deltarider

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Re: Voltage loss at Ignition switch
« Reply #6 on: April 14, 2014, 11:51:08 AM »
trebuchetxlt,
Please do the test again with a running engine. I bet your voltage drop is gone. That is what it is all about. It's from experience.
« Last Edit: April 14, 2014, 11:52:45 AM by Deltarider »
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Offline strynboen

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Re: Voltage loss at Ignition switch
« Reply #7 on: April 14, 2014, 11:57:34 AM »
have you testet vith amp meter to thek flow...in my headlight housing i only have 11,5 volt..same at coils..but 12,5 at battery..so some power goes to heating coils and generator magenet..and control panel bulb
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Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #8 on: April 14, 2014, 01:00:22 PM »
trebuchetxlt has done the correct test, and measured the loss directly across the switch.  He KNOWS there is a volt lost across it.  He just doesn't know the exact current.

Knowing the current, it is a simple math equation to solve.  Experience has nothing to do with it.  I just posted the simple and basic formulas to solve electrical unknowns.  Anyone with proper training will already know these to be true, internet "experience" notwithstanding.

ALL of the bike's current usage flows through the Key switch.  The stock bike draws right around 10 amps.

If you change the current flowing through the switch, by adding or drop loads on the circuit, the resistance will stay the same.  But, the voltage loss will be different due to ohm's law.  This is really simple math, folks.  If you can make change using money, you really ought to be able to calculate. R= E/I.

A running bike may allow vibration to improve a doggy switch contact.  But, vibration should NOT be a necessary ingredient for a key switch to operate.  In fact, vibration should have no effect on a proper key switch.

Further, a running bike should increase the voltage applied to the switch as well as all he load devices, which will increase the current flow and increase the voltage drop across the switch resistance.

If experience is any teacher, 30yrs in the electronics industry teaches way more than very reliable and basic, ohm's and watts law.

If you have lost a volt between battery and headlight.  You have either connector resistance issues or switch contact issues.  This sort of loss was NOT present when the bike was new.  When new the loss was about .2 volts.  Anything more than a 0.5V loss indicates a connectivity problem developing.
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Offline trebuchetxlt

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Re: Voltage loss at Ignition switch
« Reply #9 on: April 14, 2014, 01:21:46 PM »
Thanks for the input guys, it looks like Lloyd hit the nail on the head. I had a feeling that the problem was due to dirty contacts in the switch and it appears that was correct. I cleaned the switch and I'm now getting 12.5V from the Black lead on the switch side of the connector, so, all good there. I'm still getting a loss on the lighting circuit (Brown) where the reading is 11.5V at idle and rising to 11.8V with RPM above 3000, but, I'm not going to worry too much about that. It was just weird that when I did the initial test with the original Honda Ignition switch and the new(ish) aftermarket switch they both gave the same result. I guess the lesson here is to not trust those aftermarket switches.
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Offline Deltarider

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Re: Voltage loss at Ignition switch
« Reply #10 on: April 14, 2014, 11:24:25 PM »
Glad TT explained you it is simple. I await the results of others  :D
Quote
I guess the lesson here is to not trust those aftermarket switches.

I doubt it. I guess the lesson is the resistance was before the switch and in the connector or wire to the switch. Fiddling with it is sometimes enough.
Here's a tip (from experience again). After a long period of not using your bike you can clean the switchcontacts by vigorously switching the key (preferably with the killswitch off) say ten times. You can do the same with the killswitch (preferably with the ignitionswitch off). I do it every spring and all parts are still original. Didn't need 'simple' schemes or equations to explain that, now did I?
« Last Edit: April 14, 2014, 11:52:06 PM by Deltarider »
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Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #11 on: April 15, 2014, 12:22:32 AM »
You could also try putting fresh entrails of a goat on your dash panel at moonrise to chase away electrical demons.  Lots of folklore to support that one, too.  Works spectacularly well in the Netherlands, I'm told.
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Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #12 on: April 15, 2014, 12:27:09 AM »
I guess the lesson here is to not trust those aftermarket switches.

The internal switch contacts are physically smaller than the originals.  Less contact area yields higher resistance.  There have been many postings about early aftermarket switch failure, as the plastic that holds the small contacts in place distorts from resistance heating.  Misaligned contacts garner even more resistance and heating.
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Offline Deltarider

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Re: Voltage loss at Ignition switch
« Reply #13 on: April 15, 2014, 12:35:25 AM »
Quote
You could also try putting fresh entrails of a goat on your dash panel at moonrise to chase away electrical demons.  Lots of folklore to support that one, too.  Works spectacularly well in the Netherlands, I'm told.
Ha, ha. Where did you learn that?
We did a lot of vigorously switching in the controlroom of a theatre to clean contacts. Worked wonderful. It was a student job really, wouldn't call it the electronic industry.
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Offline PeWe

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Re: Voltage loss at Ignition switch
« Reply #14 on: April 16, 2014, 03:06:11 AM »
Relays a good idea anyway.
It is very strange that I did not installed relays 30 years ago when I worked with the electrical stuff on my CB750. I replaced all wires from the handle bar switches, soldered them as the crappy OEM solution.
Today it is obvious for me to not trust 5-7A or maybe more thru these connections.

I have so far installed 3 relays.  2 for headlight (HI-LO) and 1 for the ignition coils.
I'll install no:4 for the horn when I have another double horn with option to be replaced by a Stebel Nautilus later on.
This will then be wire no:4 3 direct from battery with a hanging fuse close to battery.
« Last Edit: April 18, 2014, 01:43:27 PM by PeWe »
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Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #15 on: April 16, 2014, 12:03:18 PM »
Relays a good idea anyway.

I do not agree.  Particularly when they are used as a convenient crutch to circumvent the repair of faulty equipment.  The stock switches handle the stock loads just fine.  But, not forever.  Nothing man makes lasts forever.  Neither do relays which add more complexity to the bike and make the next PO scratch his head when looking at the mess on the bike's wiring that no longer matches published wire diagrams.  Who here that favors relays, have actually made a wire diagram mod or addendum which stays with the bike?

If a switch is installed/replaced that doesn't have the current capacity of the original in good working order, then a relay makes more sense.  But, then the bike has a unique wire diagram, that should follow the bike the rest of it's days in existence.  Yes, even relays will fail, and so will the dodgy switch that you bypassed with relay. 

Switch contact capacity is tightly related to the size of the contact.  All switches have a make/break cycle life expectancy related to the current/power it is expected to control.

Ever read post where the it was asked where to get a whole new wire harness because the PO patched and spliced so many things that they were unable to restore it?

If a cylinder goes out on the engine, do you then add another cylinder to bypass the failed one rather than fixing the one that failed?

For a bike that is revered for it's simplicity, why add the complexity of a relay rather than just fix what wore out?
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Offline PeWe

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Re: Voltage loss at Ignition switch
« Reply #16 on: April 16, 2014, 01:16:59 PM »
My relay installation is easy to remove and reconnect as it was before. Unplug wires activating the 2 relays for Hi_LO and connect direct to the H4 bulb. Same with ignition relay. Horn relay will be of the same design. OEM cables are not changed.
I did it this way to make it possible to bypass the relay(s) if they get problems. I carefully crimped sockets and pins on correct wires (marked with labels) to  make it possible just plug it together the other way again.

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Offline Bodi

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Re: Voltage loss at Ignition switch
« Reply #17 on: April 17, 2014, 04:32:46 PM »
"With all respect Bodi but I'm afraid you've got it all mixed up. Can't make sense of your Watts."

Well... with all respect you should take another look at Ohm's law.

P=EI so (my guesstimated example) P= 5 x 1 (5 amps and 1 volt drop) = 5W power (as heat).

Or, using Lloyd's 10A current, 1V drop means 10W of heat at the switch contact.

Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #18 on: April 17, 2014, 05:55:02 PM »
Bodi,
Don't you love it when people post "experiences" that defy the laws of physics?

Cheers,
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Offline calj737

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Re: Voltage loss at Ignition switch
« Reply #19 on: April 17, 2014, 07:04:38 PM »
I'm surprised at you, TT. Did you miss the day they taught "New Electrical Math" at school? Tsk, tsk...
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Offline Deltarider

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Re: Voltage loss at Ignition switch
« Reply #20 on: April 18, 2014, 02:34:48 AM »
Quote
Don't you love it when people post "experiences" that defy the laws of physics?
Who did that? Read carefully and avoid bias. It's not he first time I have to point you at this but I must admit for some it can be much more difficult than 'simple physics'.  ;D
I maintain talking about Watts here (i.c. voltage drop) is irrelevant. That's what I ment by saying 'Can't make sense of your Watts'. And I had Ohms law in school, thank you. The power consumption in Watts is a consequence and not the cause. So it's no use discussing Watts here. How is trebuchetxlt to measure Watts with his DMM? Please show him that switch position on your DMM.  Show me and I'll buy one instantly for my collection ;D ;D.
Now, if you allow me a question, a question only someone as stupid as I can ask... 30 years of repairing electric fans and hairdryers does that also count as '30yrs in the electronics industry'? Mind you, it's just a question but you, for who so many things are 'simple', seemed the right person to ask. ;D ;D ;D

« Last Edit: April 18, 2014, 03:56:45 AM by Deltarider »
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Offline grcamna2

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Re: Voltage loss at Ignition switch
« Reply #21 on: April 18, 2014, 04:56:06 AM »
I guess the lesson here is to not trust those aftermarket switches.

The internal switch contacts are physically smaller than the originals.  Less contact area yields higher resistance.  There have been many postings about early aftermarket switch failure, as the plastic that holds the small contacts in place distorts from resistance heating.  Misaligned contacts garner even more resistance and heating.

I've taken apart a few different old OE switches(mains and handlebar) and found a warped contact backing piece which certainly misaligned the contacts and caused higher resistance.I think in a few of those the problem could have stemmed from too much tension on the wires over a few years;correct routing does help too.
« Last Edit: April 18, 2014, 11:33:43 AM by grcamna2 »
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Offline Spanner 1

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Re: Voltage loss at Ignition switch
« Reply #22 on: April 18, 2014, 06:46:38 AM »
There may be a flaw in the OP's test....... If he has 12.8v on the Red terminal at the ign. switch, when he moves the + probe to the Black wire the reading will be 0 volts until he turns the ign ON........ he says 11.8v is then the reading on the Black wire...... but the real test was to put the probe back on the Red terminal and compare it's reading with the ign. ON........ otherwise no test! I don't think he has fixed the problem ( remember changing-out the switch gave the same results)... the actual problem is very likely a crappy main fuse/ holder...... good luck  :)
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Offline grcamna2

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Re: Voltage loss at Ignition switch
« Reply #23 on: April 18, 2014, 08:20:44 AM »
I was checking the voltage at my Ignition switch, '75 CB550, and noticed that although the voltage reading at the Red wire into the switch was at 12.8 Volts it was only reading 11.8 Volts at the Black wire coming out of the switch, the reading was taken at the connector on the switch side. I thought it was probably due to resistance in the switch, it was the bikes original, so I tried it with another switch I had, admittedly it is one of the Emco aftermarket deals, but, it's not had much use, and got exactly the same reading.
It seems strange that 2 different switches would give the same results, any thoughts?

Who's that guy in your avatar pic ? He looks like a 'scare crow'  :o :) :)
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Offline Spanner 1

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Re: Voltage loss at Ignition switch
« Reply #24 on: April 18, 2014, 08:42:39 AM »
I couldn't help but have a chuckle at TT, Delta and Bodi having a fight over a voltage drop across an ign. switch when it's obvious that the poster NEVER measured the voltage on the Red terminal with the ign On....bet it's 11.8v the same as on the Black wire ..... :o

P.S..... The OP also never said that he tested with the ign. switch plug disconnected, just that he had stuck the probe in the 'switch side' of the connector.....
« Last Edit: April 18, 2014, 08:55:32 AM by Spanner 1 »
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Offline trebuchetxlt

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Re: Voltage loss at Ignition switch
« Reply #25 on: April 18, 2014, 09:33:30 AM »
I did measure the voltage with the ignition on during the initial test that's why I couldn't understand two different switches giving the same reading. I tested the Red input at the switch in Off and On positions to gauge whether the problem was at the switch or in the wire from the battery. The fusebox is a Hondaman blade type which has been on the bike for less than a year, and I did measure the voltages at that point too.
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Offline Spanner 1

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Re: Voltage loss at Ignition switch
« Reply #26 on: April 18, 2014, 09:43:38 AM »
Think you need to do that test again.... with the ign. 'on' this time . Report the voltage at the Red terminal and the Black terminal..... that's the only way to verify the switch  :)
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Offline calj737

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Re: Voltage loss at Ignition switch
« Reply #27 on: April 18, 2014, 09:54:31 AM »
It's odd, Spanner, he stated directly above that he tested the switch in both "Off" and "On" positions, yet you seem to believe he still hasn't done it properly. If you scroll up a ways back, you'll also see that after some prudent maintenance on the switch, that he remedied his "loss" and now has correct voltage on both sides of the switch.

What part exactly did he not do "properly" since it's now corrected?
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Offline Spanner 1

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Re: Voltage loss at Ignition switch
« Reply #28 on: April 18, 2014, 10:11:34 AM »
Well, the OP never said, or was he asked,until I asked , if he had measured the voltage at the Red terminal with the ignition 'on'.  ( not until Reply #25 ). If the voltage @ Red is the same as Black proves the switch is good.
Secondly, he says that a second switch 'gave the exact same results'. Again points away from the switch.... if now he reports voltage the same both sides ( after cleaning ) well great, but I'd be looking at my battery connections, 'stud' on the solenoid, main ground too......
If your sure it's a carb problem; it's ignition,
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Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #29 on: April 18, 2014, 11:04:00 AM »
I maintain talking about Watts here (i.c. voltage drop) is irrelevant.
And you're still wrong.  See any heat sinks on the ignition switch?  It is NOT designed to dissipate power.  It is not designed to consume power.  It is designed to pass power unimpeded.  Why is this not a simple concept to comprehend?
Many insulating materials distort with heat.  And, the switch contacts are internally held in place by insulating materials.
Have you never taken a switch apart?  If not, WTF are you giving advice about something you know nothing about?

That's what I ment by saying 'Can't make sense of your Watts'. And I had Ohms law in school, thank you. The power consumption in Watts is a consequence and not the cause.
You're still wrong.  And watt's law is closely tied to ohm's law for nearly everyone actually trained in the electrical matters.  Did you skip school the day after ohm's law was taught?  Here's a refresher, since you were unable to decipher the quick reference wheel I posted earlier.  P (watts) = E (voltage) x I (current)

So it's no use discussing Watts here.
Only because it doesn't help your non-sequitur argument, rather than lead to an understanding if the real issues.   

How is trebuchetxlt to measure Watts with his DMM?
Measure voltage drop and then measure (or know) the current passing the switch contacts.  Then it is a simple calculation.  P= IxE   Are we not allowed to use math per your rules?

Please show him that switch position on your DMM.  Show me and I'll buy one instantly for my collection ;D ;D
Just put "watt meter" into an internet search browser and you'll find hundreds to choose from.  I suggest you buy them all, since simple math appears to be abhorrent to you.  ;D ;D
Here's a few examples. 
http://geraiprodukcom.itrademarket.com/1503385/lutron-dw-6060-digital-watt-meter.htm
http://www.amazon.com/100-Amp-DC-Watt-Meter/dp/B005534KM6
http://www.ebay.com/itm/Brand-New-LUTRON-DW-6160-Digital-Watt-Leakage-Meter-Tester-ACV-ACA-DCV-ohms-/161040042936

However, since I know simple math, I can use any of my DMMs to find power consumption of a circuit.  trebuchetxlt already found the correct switch positions to diagnose the fault properly.
Do YOU need a remedial lesson on meter use?  Is this a serious request?  Do you even have a DMM?

Now, if you allow me a question, a question only someone as stupid as I can ask... 30 years of repairing electric fans and hairdryers does that also count as '30yrs in the electronics industry'?
Imo no, you have experience in a corner of the electrical industry.  Electronics is a bit different.  In this context I propose...

Electronics - "the branch of physics and technology concerned with the design of circuits using transistors and microchips, and with the behavior and movement of electrons in a semiconductor, conductor, vacuum, or gas."

Electrical - "using or providing or producing or transmitting or operated by electricity; "electric current"; "electric wiring"; "electrical appliances"; "an electrical storm""

I can only surmise that your 30 yr experience consisted of simple part substitution from on the job training, rather than circuit or component analysis (theory or practice).

I suspect your rejection of "Simple Physics" is the root of many misunderstandings.  Too bad, as there is nothing in this world with which we are more intimate with on a daily, second by second basis, awareness notwithstanding.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Deltarider

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Re: Voltage loss at Ignition switch
« Reply #30 on: April 19, 2014, 11:37:15 PM »
TT, it is as simple as this: every time Ohms Law is the topic you never fail to produce the most complicated scheme I have ever come across. This doesn't go unnoticed. Nor that in your posts the words 'physics' and 'math' always go accompanied by the epitheton 'simple'. But who do you think to impress? Yourself? It's a bit... let's say Tiring. It's not the scheme I would present to get people familiar with Ohm's Law. I'd rather 'simply' produce Ohms Law in it's basic form and maybe add an example. We are not debile, you know.
The topic was 'voltage loss at ignition switch'. There's no need to empty a bookshelf for that. Using the ohm- and voltfunction on a ordinary multimeter is all it takes and you will not find a Watts function on the average multimeter, automotive or not. Ever wondered why that is?
Cleaning contacts is enough and if your wiring has lived through the kilometers my bike did, you may suspect that due to aging and vibrating part of the capacity in that brittled copper is lost anyway. I maintain a voltagedrop as described above is not abnormal for a bike that old and I've seen worse. It might well be there's a similar voltage drop on mine. I don't bother as long as it starts and runs fine. I thought it was a good advice to start with cleaning the contacts by some vigorously switching. Worked for me on countless occasions and I thought I should share that experience. I always start with the simplest and can recommend that practice to anyone. It's from my experience with the laws of physics. Can't put it simpler.
« Last Edit: April 20, 2014, 12:43:54 AM by Deltarider »
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Offline TwoTired

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Re: Voltage loss at Ignition switch
« Reply #31 on: April 20, 2014, 12:42:59 PM »
TT, it is as simple as this: every time Ohms Law is the topic you never fail to produce the most complicated scheme I have ever come across.
Amazing, Ohm's law and Watt's law are the most complicated schemes you've encountered?   Just wow.   Kirchoff's laws must send you reeling in confusion.  How can you possibly understand series circuits?
  Anyway Ohm's law isn't taught at the beginning of the lesson plan.  It's not until after the Physics and the fundamentals of matter as it relates to electricity is taught first, then electrostatics,  magnetism, Voltage, current and resistance, in order to make ohm's law relevant and justified foundationally.  In fact, nuclear theory explaining how atoms have electrons and a nucleus comprised or protons and neutrons, it the root of understanding what electricity does during operation.  Everything is complicated for those determined not to delve thoroughly and gain a root understanding of the subject.  Further, you cannot hope to understand the control of electricity without a basic knowledge of math.

This doesn't go unnoticed. Nor that in your posts the words 'physics' and 'math' always go accompanied by the epitheton 'simple'. But who do you think to impress?
I'm not trying to impress anyone.  I'm trying to teach those willing to learn about how things fundamentally work.  DC theory is very basic and simple to understand compared to AC theory.  And the formulas and math necessary to understand high frequency circuitry and operation would clearly send you screaming toward an asylum.
Things become simple only after you understand the basics.  Avoid the basics and nothing relating to technology will be simple.  I define simple math as the ability to do addition, subtraction, multiplication, and division.  With these tools you can understand DC series and parallel circuits.  Avoid this math, and electrical devices will always be mystical regarding operation.   There is no need for it to be mystical, and the knowledge is available for those who wish to be enlightened.  Avoid this knowledge and your best tool for solving errant device behavior will be systematic replacement/substitution of components until the "problem" goes away.  This can be an expensive route that can be avoided with knowledge gained beforehand.

I get it, you are a neo-luddite diametrically opposed to learning how things really work, in favor of your own personal theories about how you wished they work.   Fine.  Don't read my posts or try to impede those that actually DO want to learn and have reliable understanding of physical devices.

Yourself? It's a bit... let's say Tiring.
Do yourself a favor and stop reading my posts.  They are clearly beyond any hope of understanding on your part, particularly if you refuse to learn something you haven't personally thought up.  The things I present here are not something I made up.  I was taught, either through classroom, book reading, peer group, or research during job functions (experience).  And I've used these teachings to help me understand and improve my life and the machines/devices around me.  If you don't wish to gain these benefits, just ignore me.  You'll feel rejuvenated by reveling in your own deluded sense of reality.

It's not the scheme I would present to get people familiar with Ohm's Law. I'd rather 'simply' produce Ohms Law in it's basic form and maybe add an example. We are not debile, you know.
The internet audience runs the gamut between college grads and the feeble.  You chose the audience you wish to address and I'll chose mine.
You are welcome to present any scheme you wish in your own posts, as long as it is accurate, and not based on human emotions such as wishes.  If you teach foundational flaws, be prepared to be admonished and corrected.   
The OP of this thread proved to be accomplished in his very first post in the thread.  In fact, if you noticed, he fixed his switch problem and voltage loss by refurbishing the faulty switch(s).

The topic was 'voltage loss at ignition switch'. There's no need to empty a bookshelf for that. Using the ohm- and voltfunction on a ordinary multimeter is all it takes and you will not find a Watts function on the average multimeter, automotive or not. Ever wondered why that is?

You are still wrong about that.  You cannot use an ordinary DMM to measure switch degradation, as it's inherent resolution and accuracy is less than the subject resistance you are attempting to measure.
We have already proven that to you in prior posts, which you refuse to believe or are unable to comprehend.

Can you measure a teaspoon of water by using a gallon jug with the only calibration at the one gallon mark?  No, not with any believability.

Check the resolution and accuracy figures on your DMM.  If those numbers vary more than the object under test, you can't make an accurate measurement.
A 1 volt drop at 10 amps indicates 0.1 Ω resistance.  You are fooling only yourself if you think an ordinary DMM can accurately measure that on a 200 or 20Ω scale selection.
Your credibility dropped to zero with the claim that an ordinary DMM can accurately measure degraded switches rather than outright failed switches.

http://www.eevblog.com/2009/08/21/eevblog-26-multimeter-counts-accuracy-resolution-calibration/

http://www.robotroom.com/Measuring-Low-Resistances.html

Cleaning contacts is enough and if your wiring has lived through the kilometers my bike did, you may suspect that due to aging and vibrating part of the capacity in that brittled copper is lost anyway. I maintain a voltagedrop as described above is not abnormal for a bike that old and I've seen worse.
No, it isn't abnormal for it's age.  But, it is still a failure (degradation is a form of failure) and a clue toward future catastrophe.   You can tip over the edge of a cliff, and for a few seconds, it doesn't matter.  But, given time, the lack of support will have you heading toward the cliff base.

It might well be there's a similar voltage drop on mine. I don't bother as long as it starts and runs fine.
Your choice.  But, a bit of preventive maintenance now might allow you to avoid complete replacement in the future.

I thought it was a good advice to start with cleaning the contacts by some vigorously switching.
This is a temporary sidestep of the issue.  Useful, if you are out on the road mid-trip.  I've done that myself.  If required during your pre-ride inspections, it is a sign that maintenance is due soon, or you'll eventually be parked at the side of the road awaiting help (done that, too).  If you actually look inside the switch, you can clean, resurface and re-lube the original switch, to restore full low resistance operation before melting the internal bits into oblivion, requiring complete replacement (same is true for the block style fuse holder found on many SOHC4s).

Worked for me on countless occasions and I thought I should share that experience. I always start with the simplest and can recommend that practice to anyone. It's from my experience with the laws of physics. Can't put it simpler.
Your choice to postpone the inevitable until it becomes catastrophic.  But, I think you are confusing "simplest" with "easiest" as in minimal effort for the moment.  Any of your followers are free to do so as well. 

I can only attempt to educate.  The reader has to chose to learn.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.