Author Topic: 1979 Rd50 m electrical problem  (Read 101 times)

0 Members and 1 Guest are viewing this topic.

Offline adydeere

  • Forum member
  • Newcomer
  • Posts: 21
  • Location: Munich
1979 Rd50 m electrical problem
« on: March 25, 2020, 02:07:32 PM »
Hi Guys,
The rd50 I bought has an electrical problem which I can not solve. The motor runs and has a brand new fully charged battery fitted. The loom is pretty much original as far as I can see apart from someone replacing the main red pos 6v cable from under the tank to the headlight (I have opened up the loom where the repair was).
So the problems are (with ignition on) the brake light is on so disconnected the brake switch but stays on and there is very slight power being applied to the tail lamp filament, no headlight. Start the engine and the headlight is very dim (6v 15w)  and the brake light remains bright. Disconnect the back light completely and both indicators on one side flash when tried but very dim, connect the back light and the back indicator goes off and the front one and the tail light flash. I disconected the handlebar switch and tested the brake light but nothing. I have looked at all plugs and tried unplugging front brake switch and clock lights but still the same so I am not sure where to look.
I have tried to give you as much information as possible and any Ideas would be appreciated
Many thanks for taking the time to read this.
Ady
« Last Edit: March 25, 2020, 03:29:32 PM by adydeere »

Offline Gr8uncleal

  • Club Member
  • Port Hacker
  • Posts: 955
Re: 1979 Rd50 m electrical problem
« Reply #1 on: March 25, 2020, 02:42:51 PM »
Just a few randoms, in no particular order:-

1) Bad earth(s) somewhere.
2) Aftermarket or "repaired" main ignition switch.
3) I may have misunderstood, but it's unusual for a red to go direct to a headlight (usually black, yellow or green).
4) All connecters attached to matching colours in the headlight shell/bucket.

Others will chime in with more "helpful" comments!

Good luck!
Yam RD200DX (Gr8auntiepat's)
Yam FZX700 Fazer
Yam RD400 bitsa
Yam RD350B rough
Yam RT2 almost finished
Yam DT360A almost finished
Suzi GT550J just started
Suzi 1250 Bandit regular rider
Yam RD125B (probably!) just received
Yam AS3 in boxes just received

Offline adydeere

  • Forum member
  • Newcomer
  • Posts: 21
  • Location: Munich
Re: 1979 Rd50 m electrical problem
« Reply #2 on: March 25, 2020, 03:09:23 PM »
Hi Gr8uncleal,
I have just managed to find a wiring diagram albeit in German but I live in Germany so not a problem. I can now say the headlight problem is separate as this is wired direct to the stator via the light switch so nothing to do with the battery circuit. I re soldered the earth on the headlamp holder as that was hanging off and I have checked all plugs for correct cable matching although I will take photos and study them on the laptop. The red wire has been joined to the loom a long time ago as I can tell from the tape and there was nothing else obvious.
I have attached the wiring diagram and yes a red wire goes direct from the battery to the plug in the headlamp then off to the Ignition. The ignition looks original but could be faulty so I will check that and now I have the circuit diagram I can have a look at that a little better.
Thanks Ady
Thanks for you advice and I will keep get to the bottom of this
« Last Edit: March 25, 2020, 03:40:20 PM by adydeere »

Offline martin1957

  • Forum member
  • Port Hacker
  • Posts: 1118
  • Age: 62
  • Location: Gillingham, Kent
Re: 1979 Rd50 m electrical problem
« Reply #3 on: March 25, 2020, 06:20:53 PM »
Temporarily run an earth wire from the tail light bulb outer to battery negative, the same with the left and right rear indicator bulbs.

The diagram shows there are no specific earth wires, and all rubber mounted, rubber isolated, or freshly painted frame will stop the earth return working.
Retired Widowed Electronic Test Engineer (Avionics), Age 62, Owned P50, PC50, SS50z, YAS1, YDS7, RD350B till 1978, then KH400 from 2009 onwards. Have a fully restored YAS1 on the road, and an AT3. And now a Suzuki T125 Stinger to get fired up, with another Stinger in boxes....

Offline Gr8uncleal

  • Club Member
  • Port Hacker
  • Posts: 955
Re: 1979 Rd50 m electrical problem
« Reply #4 on: March 25, 2020, 06:45:46 PM »
Temporarily run an earth wire from the tail light bulb outer to battery negative, the same with the left and right rear indicator bulbs.

The diagram shows there are no specific earth wires, and all rubber mounted, rubber isolated, or freshly painted frame will stop the earth return working.

Agreed.

Also looks like the tail light is supplying the earth to the headlight and tacho illumination light (or is number 19 the speedo?!).
Yam RD200DX (Gr8auntiepat's)
Yam FZX700 Fazer
Yam RD400 bitsa
Yam RD350B rough
Yam RT2 almost finished
Yam DT360A almost finished
Suzi GT550J just started
Suzi 1250 Bandit regular rider
Yam RD125B (probably!) just received
Yam AS3 in boxes just received

Offline adydeere

  • Forum member
  • Newcomer
  • Posts: 21
  • Location: Munich
Re: 1979 Rd50 m electrical problem
« Reply #5 on: March 25, 2020, 08:18:52 PM »
Hi Guys, thank you for your advise it is much appreciated.
I will wire the earths directly to test everything.
No 19 is the speedo and No21 the rev count.
There are two main earth points the first from the battery ring crimp onto the frame and the second ring crimp behind the charging diode under the tank this is then connected to the other earths via a solder joint buried in the loom so the headlamp earth and tail light earth are fed from No3 the ground point.
 
Yes the indicators are all fed earth from the point where they bolt on.

If it is looking like an earth problem I have plenty of wire and plenty of lock down time.
stay safe
« Last Edit: March 25, 2020, 08:33:51 PM by adydeere »

Offline adydeere

  • Forum member
  • Newcomer
  • Posts: 21
  • Location: Munich
Re: 1979 Rd50 m electrical problem
« Reply #6 on: March 26, 2020, 09:46:35 AM »
Quick update, it was a poor earth to the back light and indicators so that is solved. The front brake switch G/Y wire was grounded on the handle bars i removed that so now the foot brake light switch is working and the wires in the loom for the front brake are good too so just need to strip the switch.
However the indicators are still very dim and when the lights are switched on the front indicator and rear light flash and the back indicator goes out and this is baffling me.
I have tried adding an earth wire from the battery to the earth wire in the headlamp but that does not make any difference.
Once again thanks for your valuable time.
« Last Edit: March 26, 2020, 10:24:22 AM by adydeere »

Offline Gr8uncleal

  • Club Member
  • Port Hacker
  • Posts: 955
Re: 1979 Rd50 m electrical problem
« Reply #7 on: March 26, 2020, 10:04:06 AM »
That's great news Ady, well done that man!

Regarding your flashers, the wattage (and voltage!) of the bulbs should match what is printed on the side of the flasher relay - eg if the relay shows 21w x 2 + 3.4w, then you need 21w watt bulbs in the flashers and a 3.4w bulb in your flasher warning light. As I said, also check they are also the right voltage.

It could be, of course, that the relay is just knackered!

Almost there!
Yam RD200DX (Gr8auntiepat's)
Yam FZX700 Fazer
Yam RD400 bitsa
Yam RD350B rough
Yam RT2 almost finished
Yam DT360A almost finished
Suzi GT550J just started
Suzi 1250 Bandit regular rider
Yam RD125B (probably!) just received
Yam AS3 in boxes just received

Offline adydeere

  • Forum member
  • Newcomer
  • Posts: 21
  • Location: Munich
Re: 1979 Rd50 m electrical problem
« Reply #8 on: March 26, 2020, 10:21:52 AM »
I have run the battery down, just gave it a quick boost and tried it and it was almost perfect I think when fully charged the tail light will stop snaffling the rear indicators. I think there is a charging issue too but I am working inside a small underground car park and do not want to upset any of my neighbors when they go to the garage. I will check the diode and also have a look at the neutral light as that doesn't work either but yes I am getting there thanks to your comments.
 :-\  always more head scratching with more than one problem.

only 1v coming of the stator for charging and headlamp running at 2000 RPM so more issues there.

I found the issue, the charge/light coil is burnt out.
« Last Edit: March 26, 2020, 03:42:19 PM by adydeere »

Offline martin1957

  • Forum member
  • Port Hacker
  • Posts: 1118
  • Age: 62
  • Location: Gillingham, Kent
Re: 1979 Rd50 m electrical problem
« Reply #9 on: March 26, 2020, 06:05:49 PM »
Thats not a surprise, the A/C headlight circuit is not fused.
Retired Widowed Electronic Test Engineer (Avionics), Age 62, Owned P50, PC50, SS50z, YAS1, YDS7, RD350B till 1978, then KH400 from 2009 onwards. Have a fully restored YAS1 on the road, and an AT3. And now a Suzuki T125 Stinger to get fired up, with another Stinger in boxes....