Weird Tach Behaviour

[kz]

Now I am confused

I bought the correct capacitor and soldered it in place.

Now the tacho has start to bounce again in a different way than before and never shows more than 7000 rpm.

So, did I destroy something because I soldered in the wrong capacitor or do I touch something during mounting and dismounting and it wasn?t the capacitor in the first place?????

I really have to rig up the tacho with a signal generator for finding this annoying error.

If you come up with something please let me know.

 

[kz]

I now have rigged the tacho with a signal generator and it runs like a dream on the bench, from 0 - 12.500 rpm fast changes and slow changes.

The value the tacho shows also corresponds to the supplied frequency.

But...

As soon as I mount it in the bike the new type of bounce is back.

I measured the signal from the coil (brown lead) and 12V mains (orange + and white -).

The signals look as I like them to look, but I didn?t measure the coil signal up to more then approx. 4000 rpm, because I don?t want to be hostile to my engine by revving it up to 9000 rpm in neutral and then adjust the trigging signal on the oscilloscope.....

I really lost the thread now and do not know there to look next, at the same time it is a little bit tiring mounting and dismounting the tacho....

JD, I never should have changed that capacitor to the correct one.

Anyone who has any clue is welcome Hap? JD?

JUST HATE TO GIVE UP! :twisted:

P.S Did you get your jpegs Moto_Man and JD?

 

[Anonymous]

It seems to me that your tacho is fine, if it works on the bench. Your signal is also good up to 4000 rpm.
The signal therefore is changing above 4000 rpm. The other change that has occurred is that your bike has aged, i.e. new bikes don't do this. Something is probably breaking down.
So, there are 2 possible sources for the problem : the signal OR the 12V supply to the instrument.
If the signal is the problem, the fault could lie within the ignition coil or at the ignition trigger. Could you take a signal from the other coil to eliminate this?
Or, if you have a 12V problem, is there a fault with the voltage regulator on your bike which would allow the voltage to rise above 12-14V at 4000rpm and up?
Or, is there an intermittent open circuit in your earthing for the instruments which is caused by engine vibration above 4000rpm?

Hope this helps.

 

[kz]

Hi Brit 7.11,

Thanks for your inputs.

1.
My bike is running very good, no misfiring etc.

Do you think there still can be any disturbance from the coil?

It is possible to disconnect the lead at the tacho and replace it with a separate new lead, connected directly to the other coil.

It is worth trying....

2.
I even thought of mounting an oscilloscope on the bike, but gave up that idea, however I think I will try to connect a multimeter for monitoring the tacho 12 V mains (I changed the regulator half a year ago and measured the voltage accordingly).

Also worth trying...

3.

Do you think that the bike will run correctly if I have a malfunction at the ignition trigger?

 

[Anonymous]

Well, I think that the tacho is more sensitive to small changes in its signal. I suppose that the bike could run ok with an ignition system fault (coil or ignitor) which would cause a tacho problem.
When I changed the coils on my bike to Dyna's, it ran much cleaner. I wouldn't have said there was anything wrong before. Also, if you read the ads for "Splitfire" spark plugs they state that engines misfire many times a second. As the bike gets older this would probably get worse.
I just get a gut feeling that engine vibration above a certain rpm is causing an intermittent open circuit somewhere, possibly even in the Tacho itself.

Don't give up!!!

 

[kz]

1.
I mounted a multimeter on the bike and connected it almost directly to the tacho mains.

Without headlight on steady 14,4 V and with headlight on 12,7V throughout the rpm-range.

The tacho behaives the same way with or without headlight on/off.
2.
I connected a complete new wire from the tacho directly to the other coil.

No difference in tacho behaivior.


3.
I think that then I run the tacho in the bench I have a nice square signal with constant voltage and then it is in the bike the signal is not so nice.

Something in the tacho must be able to take care of the ripple in the signal??

I tried to see if there is any crack on the tacho board, but could not found any.

I almost got it perfect by changing the capacitors the first time so I think I will try to change them again.

Any suggestions are very welcome

 

[Anonymous]

noise on the line

noise on the line

Sounds like the tacho is being messed up by noise on the tach signal line. The signal from the signal generator will be specifically just that, no 2nd harmonics or anything, they take huge care when theyre building them to make sure of that.
On the bike its a different thing, theres huge amounts of electrical noise flying round, and bare unshielded wires to the tach in the loom acting as a big antenna. Sounds like your picking up a spurious noise signal and its bouncing the tach all over the place.
What you might look for is a spurious signal that is higher and causing the reading to spike up every so often. If you find the culprit (and the scope is ideal for this) its not a huge job to make up a noise filter to just block that frequency range. Theres a lot of this going on in homebrew efi systems being triggered by noise and causing odd running etc.
You may even be able to trace whats putting out the spurious noises and get early warning of something failing..
A filter will usually consist of a tuned circuit, either to remove a certain set of frequencies , or to only allow a certain set to pass (bandpass filter), maybe the capacitor you are changing is part of such a circuit and is tuning the noise out, maybe a inductor has shorted a turn or two out of its coil somewhere else and has changed value...
Happy hunting!

 

[kz]

IT WORKS AND HAS DONE SO FOR 3 OURS!!!!!

So, I was suspicius about the capacitors so I also changed the two Tanthal-capacitors on the circuit board without succsess.

After reading MrFluffys post about filtering I came back to the electrolyt capacitors and my first partly succses changing them.

As I wrote before I was an unlucky owner of two tachos, both bouncing.

So I started with the next tacho and changed the two eletrolytic capacitors and mounted it back and IT JUST OPERATED AS IT SHOULD .

I think that either I messed up the first tacho by soldering the wrong capacitor I got from Elfa at the first time or there are really different errors on them??

Now then I have a tacho mounted that works I'll think I give this matter a rest for a the next future.

However, on the tacho board is really not much mounted and there can only be a couple of recistors, two eletrolyt capacitors, two thantal capasitors, one diod and a special IC marked ND SM014.

I could not found the special IC anythere and it probably contains some OP-Amplifiers, it could be that this IC was distroyed on my first tacho.

Anybody who knows there to get this IC or an eqvivalent?

I want to thank you all, especial Brit 7.11 and MrFluffy for your inputs and chearing me up (was a little bit pissed of tachometers for a time).

It would also be very interessting to here if JD has come up whith something regarding his tacho (after all he started all this).

 

[Anonymous]

Good stuff!!

 

[kz]

JD,

The tacho with the replaced capacitors still works like a dream!!!

Have drove 1500 km now.

 

[moto_dan]

JD,

The tacho with the replaced capacitors still works like a dream!!!

Have drove 1500 km now.

Sounds good. Now I'll reread your instructions and possibly be able to repair mine on my '83 GS750.

 

[Anonymous]

OK one more time please?!?

OK one more time please?!?

Hello I have read the post and am happy that someone figured it out because I have the same problem on my '83 GS750ES. now the only problem is things got wired and changed so many times that I'm confused as to what goes where. The way I understand it is that I should use a 3.3uF/50V and a 4.7uF/50V capacitor? I haven't much experience with any of this so is it easy enough to do alone or should I get help or have someone do it for me? Also may I suggest someone write up a good set of instructions and have them permanently posted on the site in the Garage or some other sections, I'm sure there are lots of us with this problem.
Cheers,
Shaun

 

[kz]

This is valid for a GSX 1100 EF, 1984 and GS 1150 ES, 1984 with electronic tacho, I don't have any knowledge of other models with electronic tacho.

I put a lot of effort in this matter, unfortnally I at first got a wrong spare capacitor, due to both me and the sales guy at Elfa where reading the wrong numbers on one of the mounted capacitor.

Here are the correct figures, for the capacitor I changed on the tacho board and got my tacho working:

1 off Electrolytic Capacitor 4.7 uF, 25V, Elfa stock-number 67-013-46
1 off Electrolytic Capacitor 33 uF, 25V, Elfa stock-number 67-003-63

The max. Voltage of one of the Elfa Capacitor is 50V, higher max. Voltage doesn?t matter; the only problem is that the capacitor is a little bit bigger and a little more expensive (like 2 cents more or something, but in production this costs really matters).

You can use the Elfa numbers to get the correct values (in PDF-format) and then buy the capacitors at your local electronic dealer (or order them on-line at Elfa).

Visit www.elfa.se/en and click the ?Datasheets? button at the left of the page, then you enter the Elfa stock-number and you find a specification of the capacitors.

I have a scanned picture of my tacho board on my homepage where you can compare if your board looks the same as mine. www.karl.zellner.com

If you have normal mechanical and soldering skills this is not a problem to do yourself.

 

[Anonymous]

Karl:

Let me be the first to propose you for the GSResources "HERO OF ELECTRONICS" award. You have shown doggedness, thoroughness and diligence beyond the call of duty.

This pesky electronic tach problem has bothered people for years, without solution. I had resorted to using red pinstripe on the face of my speedometer to indicate red line in each of the first 4 gears.....I had even almost turned into Basil Fawlty (of Fawlty Towers) in the temptation to beat my recalcitrant vehicle with a tree branch. It may take a few weeks or months before I attempt the repair but at least I now know it is possible.

Heartfelt thanks and congratulations to you (in Swedish).

Simon Waters (83 GS750ES)

 

[kz]

Thank you Simon, the award really warmed, after the discussion on the forum I just couldn?t give up even if it looked very dark for a day or two.

As it looks, this is a common problem, so I will put in a summary of my conclusions in the tips and tricks area.

I'm also very interested to here if anybody else succeeds to solve the bouncing tach problem in the same way I did.

Maybe I should have a working tach as avatar after all??.

 

[Anonymous]

Hi guys sorry for my delay, I just installed the new capacitors today, and fantastic it revs past 4000 RPM now. The needle is a bit fluffy with its response but I think thats due to the deteriorating wires and connections throughout the bike. Otherwise its great!. Karl you have been extremely helpful on this unusual problem, thanks for your help

 

[Anonymous]

GS750ED electronic Tachometer

GS750ED electronic Tachometer

I read the post on the Tachometer problem. I can't get my Tach to work. I disassembeled the cluster. According to the wire diagram, the wires going to my tach should be B/W, O, and B/Y. On my Tach the actual colors are Brown, Orange and White. Does anyone know how I cross these? The previous owner hacked the wires. It appears that the wires on my harness are like the colors of the wiring diagram. Also is there a way to test the circuit board using just an Ohm meter alone? Which wire is considered the ground and which would come from the ignitor? HELP?
:?: :?: :?: :?: :?: :?: :?:

 

[kz]

Re: GS750ED electronic Tachometer

Re: GS750ED electronic Tachometer

This old thread going alive again.....

I read the post on the Tachometer problem. I can't get my Tach to work.

Is it stone dead or does it bounce?

I disassembeled the cluster. According to the wire diagram, the wires going to my tach should be B/W, O, and B/Y. On my Tach the actual colors are Brown, Orange and White. Does anyone know how I cross these? The previous owner hacked the wires. It appears that the wires on my harness are like the colors of the wiring diagram.

If I remember correct, on the GS 1150, + and - is labeled in white very small on backside of the tacho board, maybe that can help you.

Also is there a way to test the circuit board using just an Ohm meter alone?

I'm afraid not, if you wan't to check the function of the board.

 

[Anonymous]

The Tach doesnt move at all, I question if it was hooked up correctly at all. There is some discoloration on a few parts and some sort of corrsion on the board. I am wondering if the previous owner hooked it up incorrectly (not knowing where to connect the brown and white wires) and burned something up. Is there a way to test this or do I need to look for a new board?

 

[Tv]

I'm glad this thread is alive again! I posted this Q the other day. When the bike is running the tacho will sit at about 2000 revs. When I ride the bike it will slowly move up to 4000 or maybe 5000 then slowly back to 2000 no matter how much I rev it. It's not erratic and the needle does not bounce around.
I've tried replacing the capacitors as suggested in the Tips and TRicks post but nothing changed (except now the Oil Temp guage no working either - don't know what I did there)

ronev, I'll go over and check my tacho (bike is at another place), which is in bits at the moment and I'll get back to you with some wiring details. I'm keen to get mine fixed.

REgards
Tv