R8/9 Motor Drive - please measure the voltage output

[robsteve]

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Rick:

 

I just checked my battery once again, using your picture for reference.

 

I read 10.49 volts when measuring between the red and blue, red and black or red and yellow.

 

Regards,

 

Robert

 

[rick_dykstra]

Hi John. Yes, I've installed the diode the right way around. But should it be a diode? :-)

 

Rick.

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[rick_dykstra]

Thanks Robert. That nails that down.

 

Mine are:

 

Red to Black (terminal 2 to 4) - 10.66 volt

Red to Yellow (terminal 2 to 3) - 10.27 volt

Red to Blue (terminal 2 to 1) - 10.54 volt

 

Status of the battery and motor drive connected to an R8 is:

 

- all normal camera functions work;

- the motor drive shutter buttons and remote control interface are working;

- all three of the battery's LEDs are operable but only one has been lighting up upon pressing the test button, even after I charged it a couple of days ago;

- upon inserting the battery, switching on and pressing the shutter halfway, there is a 'chock' noise from the motor. Only once.

- the battery charge symbol on the rear LCD of the camera shows full, but changes to half after manually winding and firing the shutter.

 

This makes it look like the battery is drained.

 

A curious thing is, a week ago when I noticed the drive wasn't driving, the battery was showing a full charge, holding up from the last charge a couple of months ago. This retention of charge is about what I've been getting since I installed the 2000mAh cells.

 

-------

 

It's now morning and upon checking if the fairies fixed everything overnight, I see that the battery is down to one light flashing. I'm putting it through a discharge/charge cycle now.

 

Rick.

[rick_dykstra]

Maybe it is a capacitor?? Here's a good youtube video of clever soldering of a surface mount capacitor, just like my 'diode'.

 

YouTube - Surface Mount Capacitor

 

How can I establish if it is a capacitor, and if it's working?

[rick_dykstra]

And here's a good site on surface mount technology, with identification pictures. Look at number 7 in the first pic and then at my pic of the insides of my battery.

 

Identification pictures for Surface Mount Devices (SMD)

 

I'm officially changing my mind to calling it a capacitor. Good call Mark and Stephen.

 

I wonder if that diode I've soldered in is helping? Probably not doing much harm really. What it did do is give me back my 10 volts through terminal 3. That's gotta be good. And maybe it's helped me identify that the capacitor is shot. Perhaps I should I try a new capacitor there? What flavour?

[rick_dykstra]

Would the capacitor be labelled on the underside?

[rick_dykstra]

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I'm putting it through a discharge/charge cycle now.

 

Rick.

 

OMG! I've got all three lights working! Can't stop smiling.

 

Took five and a half hours! Must be the 2000mAh cells.

 

Now, cross your fingers as I load it into the motor drive. Here goes.

 

Bugger! No drive. The motor goes 'chock' but that's it.

 

And the battery symbol in the LCD on the camera back says it's half flat.

 

And now the battery pack shows only one light, and it's flashing. LOL!

 

F@#$%&*&%$#@K!

 

Voltages are:

 

Terminal 2 to 4 - 11.33 volts

Terminal 2 to 3 - 10.98 volts

Terminal 2 to 1 - 11.29 volts

 

I just shoved it back in and it worked! I don't believe this!!!! I nearly jumped out of my chair - the camera was on and it wound when the battery slotted home.

 

It's not winding as fast as it should - about the speed of a motor winder - but this is something. But now I have no lights at all on the battery!

 

I set it to Continuous High and fired off a few rounds. It started to speed up, progressively, to 4 frames per second. Woo hoo! I'm laughing my head off!

 

What next? I'll open up the back and see a sensor instead of a pressure plate? It'll start taking good photos instead of the usual crap?

 

"It's the nargles!" says wifey.

 

I'm bloody amazed at this. The poor thing is like Frankenstein's monster, given the surgery I've done, but it works!!!!

 

But not the lights. Hmmm .... what to do about that.

 

"Nothing! Leave it alone!" I hear you say.

 

I might follow your advice.

 

However, ...

[marknorton]

Sorry to be a spoil-sport, but this inexpert tinkering may result in a working motor-drive. It could equally well result in a cooked camera. The sensible approach would be to sketch out the circuit diagram/schematic which then allows us to understand what's happening.

 

Your "electronics buff" friend at work queries the use of a capacitor on the circuit board. In this sort of application, they're used for decoupling (reducing a signal's apparent source impedance) or signal conditioning in a high or low pass filter.

 

What's certain is you should not solder in a diode just to see if it works. Do you think Leica left one out by mistake? In this application, the diode will simply appear as a dead short circuit if the voltage on the anode is higher than that on the cathode.

 

You've already had smoke out of this, so something has got hot and bothered and might be no more.

 

If I were you, I'd go and lie down in a dark room until the feeling goes away, or else enlist the help of someone who knows what they are doing.

[rick_dykstra]

Yes, I'll certainly be questioning my friend's component spotting skills. Diode indeed! Not to worry - he's only an aircraft electronics engineer.

 

I'll take the jury rigged diode off and see if the motor drive goes on strike.

 

A couple of years ago this motor drive had a habit of tearing sprockets, mis-advancing and the like. This was particularly troublesome when using it with a remote trigger. It'd rip the sprockets on the last frame but keep shooting. 100 meters away, I couldn't tell. These troubles went away once I started using contact cleaner on the gold contacts.

 

It's misbehaving in the same way at the moment, so all is not well, as you've correctly suggested Mark.

 

There was a time this would have bothered me, but I've had so many Leica nargles in my cameras over the years I'm not surprised by anything anymore. I enjoy them when they work and pick up another one when they don't. I got one of the first R8s and it went back five times, at which point they sent me a new one. Three of the loaners I had failed, with light leaks or winder lock ups.

 

I hope my in-expert tinkering hasn't offended anyone. It's been an enjoyable learning experience, largely due to the help I've received here. Somewhat time consuming though, but it's taken my mind off other worries of more import but less chance of remediation.

 

Back to the screwdrivers!

[rick_dykstra]

http://www.l-camera-forum.com/leica-forum/attachments/customer-forum/105716d1222984218-r8-9-motor-drive-please-measure-img_0339.jpg[/img]

 

The diode that I'd soldered as a bridge across the ends of the capacitor we've been talking about (the one above '235' on the board) has now been removed.

 

With the battery re-connected (see, I'm learning) voltage is back to where it was, i.e. 0.68V between terminal 2 (red wire) and terminal 3 (yellow wire). Yellow is connected via a track through that capacitor to the black wire which goes to negative.

 

The camera operates as it should but there's nothing from the motor. Not a squeak. Given that it was playing up, that might be an advantage.

 

The diode bridge I installed provided a circuit around only that capacitor. 10 volts with my bridge, 0.68 volts without. Thoughts?

[masjah]

Rick

 

I'm a bit puzzled here. If there is some doubt whether the component is a capacitor or a diode, then how can you be sure (if it is a diode at all) which way round it needs to go? If it is a diode, the component will have some indication of polarity on its body (often a thin band at one end).

 

I'm sure Mark will correct me if I'm wrong, but diodes are used around relays. One is often put across the field coil (normally reverse biased) to protect the driving components from the stored energy in the coil when its current is switched off, otherwise you can get a very high voltage pulse (E = LdI/dt and all that, with a big L and a big dI/dt). I could I guess imagine a similar arrangement across relay contacts, if a highly inductive load was being switched, to protect the contacts from being welded over by a similar pulse from the driven load.

 

But the first thing is surely to be absolutely sure what this component actually is!

 

Hope this helps.

[rick_dykstra]

John, I agree that it would be really useful to know what it is, i.e. what type of component, what particular kind in that range, and it's exact specs. On Thursday I asked the local Leica techs what voltage the battery terminals should provide and they stated that Leica did not allow them to provide technical information. I've emailed Leica Germany with a question on this component - we'll see what happens.

 

The diode was installed the right way around. My electronic friend at the office was cluey enough to advise correctly how to install the wrong component. And, it worked. It bypassed what I'm sure is a faulty capacitor, reinstated the 10 volt power supply to the motor drive's relays and then to the motor. The capacitor appears to be well joined to the board, as there is continuity between each end and other parts of the circuit, which determine how the battery charge indicator LEDs should light up. Perhaps this dodgy capacitor is causing the confusion I'm seeing with the lights?

 

Upon opening up the battery to remove the diode bridge I discovered that one of my solder joints had come loose, but was held in place by the springiness of the bend in it's wire (which I had insulated of course). That might explain why the drive's proper performance (which lasted for a few minutes) suddenly went awry.

 

The motor drive is also overunning at times, which it has done intermittently before. I'm thinking this is a relay not letting go quickly when it should. There is a revolution counter on a cog near the motor. This and it's associated electronics could be telling the relay to let go. "Stop already! That's eight sprocket holes!" But it doesn't stop. Sticky relay.

 

So, I think I've been dealing with two problems. The sticky relay that has come back to haunt me, at the same time as the battery decided to play up. Thanks mister motor drive! Not.

[marknorton]

John, you are correct that diodes are used to suppress the self-induced EMF generated across a relay coil caused by the magnetic field collapsing. The voltage has the reverse polarity of that which energised the coil in the first place and a normally reverse biased diode effectively short circuits it. Without it, the maximum working voltage of the transistor driving it might be exceeded. Some relays have a diode built in.

 

The capacitor between the yellow wire and ground (the black wire) does not actually conduct electricity but serves instead to smooth or filter the signal on it. These capacitors are small - typically 0.1 uF and you will see lots of them on a typical circuit board, for example, the top of the M8:

 

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Rick, where does the other end of the yellow wire go? Both ends. Are the shrouded connectors at the bottom are the battery pack? At the other end (soldered to the circuit board, apart from the track to the capacitor, where else does it go?

 

The three terminal device below the red wire is a transistor and that may be used to switch signals. Also, the soldered connection next to the "+" looks bad.

[rick_dykstra]

Mark,

 

the picture shows the entire length of the yellow wire. From the top it runs from where it is soldered to the board down to the battery terminal, providing a connection to the motor drive. You're right, the shrouded connectors are the battery pack. I believe the only function of this circuit is to assess the state of the battery and light up the three LEDs accordingly when the test button is pressed.

 

From where the yellow wire is soldered to the board it runs along the track that can be seen on the surface of the board, which has the following connections to tracks on the opposite surface:

 

- on its way down to and just to the right of the capacitor it joins an opposite surface track (thin) that runs down to 16 pin chip (the top left corner of which is just visible) labelled;

 

bq2010

9925d107

 

- the track from the yellow wire then goes through the capacitor;

 

- the track then goes left from the capacitor and joins the black wire;

 

- before it reaches the black, it joins an opposite surface track of medium thickness that runs down to a junction at bottom left of the board, which fans out to five components. These are the one you mentioned might have a bad joint (labelled 105f. The joint is OK.), the pink thing to the left of it (that measures 1 one way and -12.12 with the multimeter set on 20kohm), the black resistor (?) to the right (labelled 1303), another pink thing (that measures 1 and -34.9 with the multimeter set to 200kohm), and a third pink thing (that measures 99.5 and 95.4 at 200kohm). From the junction a track also runs out along the ribbon seen on the left of the picture, to the push-to-test button for the LEDs. The ribbon going to the LEDs has six tracks all together.

 

I'll draw a diagram for this circuit and take a photo showing the whole thing.

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[marknorton]

Those negative resitance values are due you still having the batteries connected and are influencing the reading.

 

As I understand it, there are 4 connections to the battery pack. You could do worse than show how those connections are wired... Isn't there a thermistor in there as well?

[rick_dykstra]

Mark, here's the circuit diagram for the Leica R8 / 9 Battery Pack. And a picture of the circuit card. I'll scan and repost the diagram. Let me know if an emailed high res pic of the diagram would help.

 

The dodgy capacitor is at the upper left of the diagram. It has solder residue on it, but is properly mounted.

 

There's a track from pin 10 of the 16 pin chip that runs to the transistor, but I can't see which terminal of the transistor it goes to.

 

So, the challenge is to get all three LEDs working again. Only no 1 works at the moment. The capacitor is looking guilty. When it is bypassed voltage along the yellow wire jumps from .68V to 10.5V, just like Robert's battery.

[rick_dykstra]

And here are the pics ...

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[rick_dykstra]

battery terminals

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[rick_dykstra]

Scan of R8 R9 battery pack circuit diagram

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Hallo,

Look here: Interesting Leica gear

[rick_dykstra]

Re the transistor and the track coming from pin 10 (?) of the chip, there is 0 resistance when probing the transistor's bottom left pin.