Author Topic: CB750 1978f fried electrics  (Read 1154 times)

Offline CornerstoneCB

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CB750 1978f fried electrics
« on: March 30, 2019, 06:37:45 AM »
Hi there,

Can anyone help? I made the rookie mistake of jump starting my 1978 F1 from a running car! Now when i turn the ignition key there is no lights on or power anywhere. I only just bought this bike and it ran fine before this.

Can anyone tell me where to start? I read it may be the main fuse? Where is it located?

Thanks
Bikes:
1978 CB750 F1
2003 HORNET 600
1993 CB500
1980 CN100
1971 CB125

Offline kevski

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Re: CB750 1978f fried electrics
« Reply #1 on: March 30, 2019, 06:50:59 AM »
Either under the seat or behind one of the side panels.

Offline CornerstoneCB

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Re: CB750 1978f fried electrics
« Reply #2 on: March 30, 2019, 07:15:36 AM »
Thanks kevski.

So i looked behind the side panel and there is a bank of five fuses in a box. Some fuses are missing but it started ok before the jump start. Is there one particular fuse to look for or is it likely that everything is fried?

😭
Bikes:
1978 CB750 F1
2003 HORNET 600
1993 CB500
1980 CN100
1971 CB125

Offline Bryanj

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Re: CB750 1978f fried electrics
« Reply #3 on: March 30, 2019, 08:11:27 AM »
Fuses should be labeled main head and tail. The battery could be totally goosed, are you saying there is nothing when connected to a slave battery?

Offline CornerstoneCB

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Re: CB750 1978f fried electrics
« Reply #4 on: March 30, 2019, 09:16:48 AM »
Hi beyanj,

Originally there was power. I (stupidly) couldnt wait for a new battery to arrive! So i connected the +\_ to my car.

Now i have put new battery in and there is nothing. The ‘dash’ lights dont come on when i turn the ignition. Cant even jump start it.

?

Thanks
Bikes:
1978 CB750 F1
2003 HORNET 600
1993 CB500
1980 CN100
1971 CB125

Offline Bryanj

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Re: CB750 1978f fried electrics
« Reply #5 on: March 30, 2019, 09:24:53 AM »
Just connecting the car battery, even with engine running should not "fry" anything. It is more likely that something has come disconnected or missed. Almost impossible to do distance diagnosis on electrical problems i am afraid

Offline Spitfire

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Re: CB750 1978f fried electrics
« Reply #6 on: March 30, 2019, 09:29:48 AM »
I did have a problem with the fuse holder on my F1, stopped at the daughters house turned off the bike and when I went to go home it was dead, turned out to be corroded wires on the back of the fuse box, the front looked great but the back was shot. Same replaced and away we went.

Cheers

Dennis
1976 CB750F

1977 CB750F2 In bits

1964 BSA A65R In bits

Offline CornerstoneCB

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Re: CB750 1978f fried electrics
« Reply #7 on: March 30, 2019, 09:35:45 AM »
Thanks all!
Bikes:
1978 CB750 F1
2003 HORNET 600
1993 CB500
1980 CN100
1971 CB125

 

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