The Canon EF "Black Beauty" no power.

[cerber0s]

Hey,

I bought a bunch of FD lenses for my F1n (50mm f1.4, 135mm f2.5 and 35-70mm) and sort of got the EF with them, that's the way I see it anyway

Now it seems like a nice camera and everything seems to work well except there's no power, neither to the lightmeter or to the electronically operated shutter. I've tried two sets of brand new batteries and it's equallt dead and the battery check is also dead. Since everything is equally powerless I suspect something early in the circuit so I figured I'd open it up and see what's going on.

Has anyone taken one apart? It looks pretty similar to the F1.

 

[Chan Tran]

Hey,

I bought a bunch of FD lenses for my F1n (50mm f1.4, 135mm f2.5 and 35-70mm) and sort of got the EF with them, that's the way I see it anyway

Now it seems like a nice camera and everything seems to work well except there's no power, neither to the lightmeter or to the electronically operated shutter. I've tried two sets of brand new batteries and it's equallt dead and the battery check is also dead. Since everything is equally powerless I suspect something early in the circuit so I figured I'd open it up and see what's going on.

Has anyone taken one apart? It looks pretty similar to the F1.

Try to install only one battery. It doesn't make sense but one of my EF works only with 1 battery.

 

[vlasta]

Thoroughly clean contacts, including threads on the body and battery caps !!!

 

[cerber0s]

After poking around a bit I suspect the on/off switch. Does anyone know how to break into the top part of one of these? The screws are a dead giveaway but the cranks and wheels are less so.

 

[cerber0s]

I found a service manual with schematics and notes online and after measuring I think I have located the fault. The batteries are supposed to be connected in series and the circuit will operate (the battery LED at least) down to 2.31 volts. The series connection from battery one positive to battery 2 negative is missing and must have been broken off at some point. Soldering a jumper will be a bit tricky but should be doable. If that is all it takes remains to be seen but having the correct voltage supplied to the circuitry is a pretty good start.

 

[flavio81]

I found a service manual with schematics and notes online and after measuring I think I have located the fault. The batteries are supposed to be connected in series and the circuit will operate (the battery LED at least) down to 2.31 volts. The series connection from battery one positive to battery 2 negative is missing and must have been broken off at some point. Soldering a jumper will be a bit tricky but should be doable. If that is all it takes remains to be seen but having the correct voltage supplied to the circuitry is a pretty good start.

The batteries are NOT ALWAYS IN SERIES on the EF!
The holder HAS NO SERIES connection!!

Please study the circuit thorougly,. There is one part of the circuit that uses 1.5V and the other uses 3.0V (two batteries).

Before changing any wiring, thoroughly clean the battery contacts. From personal experience I have found a case in which the contacts look clean yet there wasn't enough voltage when tested with a multimeter (!)

The battery holder can be easily removed so you can resolder the wres if necessary (to preemptively correct cold solder joints)

Finally, when you get the machine running again, tape the underside of the battery holder with electrical tape. The soldered contacts are too close to the chassis which is ground. So energy leaks there. Maybe this is also the problem?

 

[flavio81]

Attachment: How the underside of the battery holder looks like in a healthy EF.

 

[cerber0s]

The batteries are NOT ALWAYS IN SERIES on the EF!
The holder HAS NO SERIES connection!!

Please study the circuit thorougly,. There is one part of the circuit that uses 1.5V and the other uses 3.0V (two batteries).

Before changing any wiring, thoroughly clean the battery contacts. From personal experience I have found a case in which the contacts look clean yet there wasn't enough voltage when tested with a multimeter (!)

The battery holder can be easily removed so you can resolder the wres if necessary (to preemptively correct cold solder joints)

Finally, when you get the machine running again, tape the underside of the battery holder with electrical tape. The soldered contacts are too close to the chassis which is ground. So energy leaks there. Maybe this is also the problem?

Attachment: How the underside of the battery holder looks like in a healthy EF.

Cheers mate! You're right, the service manual I found has hand written notes in it and those said serial and had a hand drawn diagram showing it.

It's working now and the reason it disn't before is a bit embarrassing. The batteries were too small and didn't make contact with the positive plate. Both my Nikon F2 and Canon F1 are perfectly happy with batteries that are a bit smaller than the original but the EF was not.

Thanks man!

 

[flavio81]

Cheers mate! You're right, the service manual I found has hand written notes in it and those said serial and had a hand drawn diagram showing it.

It's working now and the reason it disn't before is a bit embarrassing. The batteries were too small and didn't make contact with the positive plate. Both my Nikon F2 and Canon F1 are perfectly happy with batteries that are a bit smaller than the original but the EF was not.

Thanks man!

I'm glad it works! I'd suggest to tape the underside of the battery holder with electrical tape. This can prevent premature battery drain

Finally, should you be tempted to open the camera top, be careful not to touch the IC branded ,"toshiba": it is VERY sensitive to static discharges.

This isn't an easy machine to disassemble btw.

Enjoy the EF! It's Canonista favorite.

 

[cerber0s]

I'm glad it works! I'd suggest to tape the underside of the battery holder with electrical tape. This can prevent premature battery drain

Finally, should you be tempted to open the camera top, be careful not to touch the IC branded ,"toshiba": it is VERY sensitive to static discharges.

This isn't an easy machine to disassemble btw.

Enjoy the EF! It's Canonista favorite.

Thank you! Not the least bit tempted to open it now that it works