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R8/9 Motor Drive - please measure the voltage output


rick_dykstra

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Hi folks. Re my thread below on fixing my R8 motor drive, could I ask a few motor drivers to measure the voltage output of their batteries please.

 

With the battery sitting upright as it would in the drive and counting the contacts from the top down, please advise the voltage between:

 

a. contacts 2 and 4. This should be around 9V

b. contacts 2 and 3. My battery is showing 0.75V, but what is yours?

 

Thanks.

 

See the dissection pics of my Motor Drive on my other thread below. :)

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Rick, I am convinced the old battery that came with my motordrive is stale because the charger went green/ready far faster than the 1 and 1/2 hour time period Leica states in the instruction manual that it should. Also, when I pressed the button on the charge indicator on the back of the drive, only the red light on the left was and is lit, indicating substantially less than a full charge was effected. Meanwhile, B&H Photo currently does not have any of the replacement batteries in stock. Shucks!

 

Terry

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Rick, I am convinced the old battery that came with my motordrive is stale because the charger went green/ready far faster than the 1 and 1/2 hour time period Leica states in the instruction manual that it should. Also, when I pressed the button on the charge indicator on the back of the drive, only the red light on the left was and is lit, indicating substantially less than a full charge was effected. Meanwhile, B&H Photo currently does not have any of the replacement batteries in stock. Shucks!

 

Terry

 

Hi Terry. From what you've said it sounds like your battery has been sitting idle for a number of years without a charge. I don't think this is their preferred lifestyle. When you mentioned the short times it took to discharge and recharge I did think, "Hmm, not sure that battery is full of beans".

 

So, why not get out your soldering iron and do what I did! Fill it up with new cells, perhaps even slightly more powerful ones. No need to go crazy though. Look at this thread which I linked in my other motor drive thread.

 

http://www.l-camera-forum.com/leica-forum/customer-forum/56224-put-new-cells-my-motor-drive.html

 

Let's take our discussion over to that thread. I'm hoping this one will get me some readouts on battery pack voltages.

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The "in depth" assessment is that this is a can of worms - you definitely should not have powered the motor from an external source without first disconnecting it. It sounds like you have cooked something in the electronics - a forward biased transistor, part of the flex print, welded relay contacts, who knows?

 

I think your best option is to send it back to Leica for (an expensive) repair, or look for a secondhand replacement.

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Hi folks. Re my thread below on fixing my R8 motor drive, could I ask a few motor drivers to measure the voltage output of their batteries please.

 

With the battery sitting upright as it would in the drive and counting the contacts from the top down, please advise the voltage between:

 

a. contacts 2 and 4. This should be around 9V

b. contacts 2 and 3. My battery is showing 0.75V, but what is yours?

 

Thanks.

 

See the dissection pics of my Motor Drive on my other thread below. :)

 

Rick:

 

I am getting 10.5 volts on both measurements.

 

Robert

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I blame myself for my motordrive battery failure because I failed to follow the instruction manual's statement of "It should become a habit to charge the batteries completely before every lengthy period of idleness and, to prevent a complete discharge, also to recharge them regularly at room temperature approximately every six months." I recently thought I'd also ruined a Metz CL4 flash unit because I put it in a drawer for several years, failing to occasionally charge its capacitor "every three months", but multiple attempts to get it to fire up with fresh AA batteries eventually surprisingly, finally resulted in it powering up. Phew!

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Rick:

 

I am getting 10.5 volts on both measurements.

 

Robert

 

Thanks Robert. Now that's interesting - and unexpected - and different from my battery. I'm sure you checked a few times.

 

Geez, Mark might have been right with one of his first suggestions - it could be that the battery is the problem. If so, that would be good. The drive itself is still working despite my surgery (bloody miracle really).

 

Robert - could I trouble you in the same way Houston would? "Please check again and advise. Over". Thanks for that. My motor drive is a patient on the table who might not actually need the heart/lung/liver transplant. Much appreciated.

 

Anyone else want to save my patient from the knife? Check your motor drive voltages as per the first post and advise. Thank you. :)

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The "in depth" assessment is that this is a can of worms - you definitely should not have powered the motor from an external source without first disconnecting it. It sounds like you have cooked something in the electronics - a forward biased transistor, part of the flex print, welded relay contacts, who knows?

 

I think your best option is to send it back to Leica for (an expensive) repair, or look for a secondhand replacement.

 

Dead right about the can of worms. That goddamn relay that wasn't working when I pulled it off the board started working again the next morning. So I temporarily soldered it back in place with 8 short wires, reconnected the battery - and - no driving. Power is not getting to that relay.

 

I've been suspecting the other relay, the one mounted near the floor of the case, but my tests show that it looks OK.

 

The motor drive is still working in all other respects. I'll wait for confirmation of battery outputs from Robert, and others hopefully.

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Hi Rob. Thanks for the confirmation.

 

I'm counting it as good news that my Motor Drive problems might be the battery pack.

 

Interestingly, today I saw an online store advertisement for a battery pack that is 2100mAh. My original one from '99 was 1500mAh, and the batteries I put in as replacements are 2000mAh.

 

As to the wiring to the terminals, I didn't make any changes there. All I did in re-packing the battery with new cells was unsolder the black and red wires from the group of old cells and resolder to the new cells. The thin blue wires do indeed go from terminal 1 (as I've numbered them) up to the thermistor and then back to the little circuit board. If that's wrong, then Leica done it, not me! :) But I think it's right.

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Terminals 3 and 4 are connected to the negative end of the battery pack. But, after the thin wire that runs from Terminal 3 connects to the circuit board there is a diode separating it from where the thick wire from Terminal 4 connects. This diode is not working. That is, it is open circuit - can't get a reading in either direction.

 

I could rig up a bridge for this diode, if I could identify its characteristics. :-|

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Diodes are pretty generic components, if you know if it is germanium or silicon and the max. current, then you can replace it with pretty much anything with the same or higher current specification (replace silicon by silicon diode of course, same for germanium). Other than that diodes are not critical components. The voltage (10 V or so) is not going to be a problem. If it is a Zener diode then you need to know the Zener breakdown voltage.

 

Can you read the series nr. of the diode? Then just Google "diode + series nr." and you should get the specs. easily enough.

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Thanks Stephen. This component is so small there's no room on it for any writing. I'll see if I can get a decent pic to post. Hang on.

 

OK, can you see where the black and yellow wires are soldered to the board? In between these in the circuit (slightly below in the image) is what I think is a diode. But as mentioned above it is open circuit when tested. Given that I'm getting 10V at the battery terminal for the black wire and 0.6V for the yellow wire, I suspect that 'diode' is not working properly. Any suggestions as to the kind I could buy to try as a wired in replacement? It would only have to be a functional replacement, not form and fit. I would just bridge around it. Note that this one is dark grey, while others (bottom left of board for example are cream/tan coloured)

 

If I'm wrong and it's not a diode, please tell me.

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Hi Mark. The yellow goes down to terminal 3, seen at the bottom of the pic.

 

I get 0.68V between terminal 2 (positive, red cable) and terminal 3. Robert gets 10V.

 

Both Robert and I get 10V between terminals 2 and 4.

 

Inside the motor drive, terminal 2 (positive) connects to a broad track and goes to the relay on the floor of the motor drive (relay 1). The track connects to the common pins and emerges from the normally closed pins and runs up to the second relay.

 

Terminal 4 (negative. High power?) connects to broad tracks that go to the upper relay (relay 2, the one I pulled out) which I believe provides forward and reverse motor function.

 

Terminal 3 connects to thin tracks which go to the coil of relay 2, and elsewhere.

 

So, I'm thinking the circuit between battery terminals 2 and 4 provides 10V higher current that runs through the two relays and then to the motor. And, the circuit between battery terminals 2 and 3 provides 10V lower current to power the rest of the control circuit, including the relay coils.

 

What's causing the battery to measure such a low voltage between terminals 2 and 3?

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That's two votes for a capacitor. :-)

 

In the belief (possibly mistaken) that it's a diode my wife and I did a four hands test, me holding the diode as a bridge across that component and she holding the probes. We got 10 volts between terminals 2 and 3, just like Robert's battery. Woohoo! Inspired by this I soldered that diode (1amp, 1000V) in place and put the motor drive back together.

 

The camera is showing the battery is almost flat. I can hear the motor trying to drive, with a short 'chock' noise, the first time the shutter is pressed upon inserting the battery. So there's some good news there. I'll put it through a charge cycle and see if that helps.

 

I thought I was on a winner there. Bugger!

 

A friend at work who's an electronics buff said, "What would a capacitor be doing there?"

 

Clues?

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That's two votes for a capacitor. :-)

 

In the belief (possibly mistaken) that it's a diode my wife and I did a four hands test, me holding the diode as a bridge across that component and she holding the probes. We got 10 volts between terminals 2 and 3, just like Robert's battery. Woohoo! Inspired by this I soldered that diode (1amp, 1000V) in place and put the motor drive back together.

 

The camera is showing the battery is almost flat. I can hear the motor trying to drive, with a short 'chock' noise, the first time the shutter is pressed upon inserting the battery. So there's some good news there. I'll put it through a charge cycle and see if that helps.

 

I thought I was on a winner there. Bugger!

 

A friend at work who's an electronics buff said, "What would a capacitor be doing there?"

 

Clues?

 

Rick

Presumably you are sure which way round the diode should go?

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