GT550 LED display

[Stevo58]

Hi out there...
This is a bit of an odd one.

Had an issue with the gear indicator display, it was showing gear 4, even with the switch mech on the selector end un plugged. No mystery there - just a blown display, probs the driver chip shorted out, so I posted for advice and Allen kindly pointed me to a modern replacement on the internet, which I have fitted and it works ok... but....

Now heres the thing. When the old display was connected, when you turned off the bike from the ignition switch, it gently faded out over about a minute. I thought this may be a symptom of the display being shorted inside, but the new one does the same?

If you pull the orange "Live " wire out it goes straight out - so there must be some residual voltage being bled into the circuit somewhere, voltage that eventually "dies" out.

So have any of you seen this before? I will do some poking around with a volt meter over the weekend, I will also unplug components to see if any affect it - it does have an electronic ignition fitted by the previous owner, so I will isolate that as well.

If I find out what it is I will post, but if anyone has done the hard work and solved it, that would be great.

All The Best

Steve

[Alan H]

If the display slowly fades when ignition is switched off, there's probably a capacitor 'somewhere' in the circuit that slowly discharges which causes the fade. Not knowing the schematics of the actual display unit, I have no idea where it is! Unless it causes a problem, I wouldn't worry though. 70s tech brought into the 21st century sometimes throws a curve ball.....
Started my 550A a couple of days ago and a couple of segments on the zero didn't work - all the other numbers are fine, so I might just disconnect the neutral line from the digital bit, ('green' light is ok) and do away with the zero. The 550B is fine, & the 550J doesn't have the number display of course. Wonder what fun I'll have with the GS550 display that I'm fitting to the GT550M Dunstall. What could possible go wrong there......

[markush]

I've had this behavior with LEDs too. There is a capacitor in the original flasher relay (3-pin type with ground connection in the bracket). This could be the cause of a fading LED, but only if no other device such as a light or ignition (kill switch) is connected when the ignition key switch is turned off. Otherwise the capacitor would immediately discharge via the said devices.

[Stevo58]

Hi Lads,
Thanks for that -I have isolated the electronic ignition and also the rectifier - but no banana there, I will disconnect the flasher relay later and let you know.

I rekon Alan (sorry mate, kept on mis-spelling your name) is gonna have top fun with the Dunstall .... as a pointer, on the original set up with th Tosh display, the rotary switch unit is not earthed (there is a center earth contact that was not soldered to earth) - it used an earth from the display itself in the headlamp - so Orange live, black/white earth plus the six sender wires. On the new display it has no earth, so I had to ground the center pin on the rotary switch for it to work, the other headlamp earth now redundant....

Unfortunately the bike looks like and explosion is a spagghetti factory at the mo...(LOL)

All the Best,

Steve

[Stevo58]

Woo Hoo,
Spot on Mark!!
Disconnected flasher relay and it all goes off as soon as you turn the key to the off position - will ping it open to see what is in there, probs a diode has gone off...will check and post laters.

Thanks guys for your input on this one..

Steve

[Stevo58]

Hi again...
Opened the flasher unit and all looks good, but there is something "potted" in the lid/cover, which I presume is a Capacitor - does anyone know the value of it - I could pop one "In Line" and see if it fixes the issue......

Kind Regards

Steve

[Alan H]

Personally, I'd just get another off ebay.

[markush]

Yes, just install a different flasher relay from the accessories.
The original two-pole relay from e.g. GT250 also works.

But why all the effort?
If I understand correctly, the wiring harness has just been taken apart.
But if everything is assembled correctly and e.g. while the ignition key switch is turned to off, the neutral is engaged and the neutral indicator light is on, the capacitor is immediately discharged via this lamp. Likewise, when the kill switch is on, the capacitor is discharged via the ignition.
The slow fading of the LED hardly occurs with what I call normal use.
Or do you always first turn off all the lights, shift into gear and set the kill switch to off before turning the ignition key to off?
Or, if the LED gets dim and you are annoyed about it, just press the brake and it will go out due to the discharge via the brake light.

[Stevo58]

Hi Mark and Alan,
you are right, why bother - the newer solid state units are as cheap as chips (yep I know chips aint cheap anymore but you get my drift) - I just get stuck in a stubbon mode sometimes and think everything can be fixed when it just isnt worth the time.

So I await the arrival of the new unit - thrown over the fence by Hermes...... I wonder if it will fit in the old can lid so it looks "original".... Ha - there I go again!!!

Thanks as ever

Steve