R8/9 Motor Drive - please measure the voltage output

[rick_dykstra]

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Stephen, have a squizz at your PMs.

 

Here's a smaller pic of that diagram.

 

R8 Motor Drive power circuitry.

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[SJP]

Thanks for the PM are the drain polarities of both MOSFETs the same? On your diagram I could not see black and red going to the other MOSFET.

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[rick_dykstra]

Yes, you're right. The first MOSFET has a red line going into it at S and coming out of it at D. I've drawn it this way to show how the positive track finds its way to the red wire that goes to the motor. It might help to look on page 2 of this thread for the pic showing both MOSFETs. S is the bottom right pin on both. The drain in the middle pin (and the big one at the top of the case too I think). The drain for each MOSFET connects to its respective broad track up above it.

[rick_dykstra]

It's been a couple of weeks ...

 

I ordered a small collection of parts from Mouser in the US, on a Monday. Received them in Australia on Thursday. Mouser are good!

 

First I replaced the blown BAV70 switching diode, the one that controls the coil in the 'upper' relay. The upper relay switches power to the motor, so that it will either advance or rewind.

 

Next I soldered in a new power MOSFET. See the pics above for the position of this one. It has the job of stopping the motor dead after each wind-on by briefly reversing the current flow.

 

And it works! Putting the completely disemboweled motor drive back together was a lot of fun.

 

So far all I've done is fix the damage I caused with my 'inexpert tinkering'. The bq2010 gas gauge chip in the battery is next on the agenda and will be a tricky job to replace. For the moment I've added a short light gauge wire between battery terminals 3 and 4, which has the effect of bypassing the chip's 'Battery Empty' function, which appears to be malfunctioning. As Mark Norton first guessed, this was probably the problem all along.

 

Many thanks to Mark and Stephen for their help with this project. I'm not done yet but am quite pleased with getting the drive working again. Phew!

 

Any hints on removing and installing a 16 pin chip, the bq 2010 in the battery, using simple soldering hand soldering methods would be helpful.

 

Please also see my new thread/question on how to stick the leatherette covering back on like new. Leica use a thin film of double sided adhesive.

 

Regards, Rick.

[marknorton]

I'm impressed, good job!

 

Unsoldering surface mount components is difficult without the right tools. The great problem is that too much heat/mechanical force will lift the copper lands off the board. You have to avoid at all costs levering the chip off the board. Fine if the lands stay stuck to the board, bad news if they don't.

 

If you have a replacement chip, try snipping the pins close to the old chip to the point where you can remove the chip just leaving the pins on each land. Then, work on each pin with a solder sucker or fine desoldering braid to tidy up each land; let it all cool, clean with an organic solvent and a toothbrush (your wife may not take kindly to you using hers and loose interest in the project), then tin each land and the corner pins of the new chip. Position the chip/briefly heat each corner pin to fuse, let it cool, then work on each pin.

 

An alternative way to remove surface mount components is to use hot air, but if you have not got the right tools, it's tough to do. A hot air gun, such as you might use to remove paint, is too strong and too broad a source of heat, it will just end up melting everything.

 

Are you going to show us your handiwork?

[rick_dykstra]

re pics - I was so pleased with getting it back together and working again I was thinking of making a short movie. Pictures and sound.

 

I also adjusted the end of film spring tension. I need to buy some out of date films to test this with - all of my old test films have torn sprocket holes at the end already.

 

Thanks for the tips on removing/installing the bq2010. I'll approach that with care.

[rick_dykstra]

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With some spare time over the Christmas break I've had a go at replacing the bq2010 battery charge 'fuel gauge' integrated circuit in my R8 motor drive battery pack. It looks like this has been successful. The camera/drive/battery are all working as they should, which I am rather pleased about.

 

I decided to replace the chip as the investigations and repair work described in this thread were making it look guilty of falsely advising the camera/drive that the battery pack was drained. A temporary work around was to solder a small wire from the battery pack's terminal 3 to terminal 4, which bypassed the chip's battery charge assessment function and enabled the camera/motor drive to advance/rewind. This hack also bypassed the battery pack's over-discharge protection, so keep that in mind.

 

To get myself in the mood to attempt the chip removal/replacement I watched a number of youtube videos and kept in mind the advice I'd received here. The trick is to avoid lifting the tracks from the flexible circuit. A removal method I thought was very interesting (but didn't use) was laying the circuit on an upturned clothes iron, to melt the solder and allow the chip to be lifted off.

 

Not having any fancy tools, my method was to suck up as much of the solder from the 16 pins with solder wick and then warm the pins with a fine (curved) soldering tip while ever so gently prising with a tiny screwdriver. It came off more easily than I expected and without any damage to the circuit.

 

I cleaned up the pads with the iron and solder wick where necessary and then used a flux pen to prepare the pads and the chip's legs for soldering. Installing the new chip was easy, by running a soldered tip along the legs. I inspected with a magnifier and tested for continuity.

 

Conclusions:

 

- it's possible to breath life back into 'dead' R8/9 battery packs;

- if a motor drive is playing up, assess whether the problem is the battery before tearing down the drive; I recall Mark Norton mentioning this early on.

[rick_dykstra]

Here are some pics repeated for easy reference.

 

The first shows the bq2010 battery gauge chip on the flexible circuit in the battery pack. This is the chip I replaced.

 

The second pic shows wires soldered to the battery terminals, for testing whilst in use. To bypass the battery charge assessment function of the battery pack, solder a short loop of fine wire between terminals 3 and 4. Terminal 3 is second from the left in this pic (with yellow wire) and terminal 4 is on the left (blue wire).

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[TomM]

Mark and Rick,

 

I have read your correspondence with some interest. I wonder if one of you could give me some advice?

I have had my battery pack re-celled by the local Panasonic agents using replacement cells of, I believe, the original type (have not seen inside the unit). After charging it, only one light will shine and after a day this will only blink rapidly. I have taken it through the long discharge and recharge cycles approximately ten times (takes about 5 hours plus 1.5 hours to complete). There has been no change in the end condition.

On the camera, the motor drive allows the exposure meter and the viewfinder display as well as the shutter to work properly but there is no sound or apparent effort to turn the motor. The camera battery display shows "full". Camera otherwise is functioning and the motor drive worked well before the accumulator was re-celled.

Please can you suggest what I should do next.

 

I measured voltages as follows: 4 to 3 is 1.6V; 4 to 2 is 10.8V; 4 to 1 is 1.6V

 

Thank you. Tom

Edited November 14, 2010 by TomM
Omitted some pertinent information

[rick_dykstra]

Hi Tom. The fact that you found this thread shows that the forum is working. Great!

 

I learnt a lot when I pulled my battery pack and motor drive to bits, creating some problems for myself along the way and then persisting with fixing them. It's good that you've noticed that Mark is the electronics whiz 'round here.

 

One quick caution - if you do dive into the battery, please be careful if probing with a meter. The bq2010 'fuel gauge' chip in particular is easily damaged.

 

I'm out of town at the moment but will get back to you soon. I might need to look at my own batteries to get my head around what's going on with yours.

 

Regards, Rick.

[rick_dykstra]

Tom,

 

what's the history of the battery and its status before the new cells were put in? Did it work properly but in the end not hold a charge for long?

 

10.8V between terminals 2 and 4 is close to what I get for a charged battery. Here's a question - does the battery hold that charge even though the light starts blinking after a day? The answer could indicate whether there's a problem with the cells, how they've been put in, or possibly with the circuitry in the battery. That bq2010 could be playing up.

 

If you're not over it yet, keep going with the discharge and recharge cycles. I've seen this work out, eventually.

[TomM]

Rick,

 

Thank you for your very quick response. I purchased the drive and battery used. When I charged the battery all three lights lit up for a few days only but the batteries did not hold the charge for long hence my decision to replace the cells. So far the voltage seems to be remaining constant after a few days since the last attempt to recharge. I will follow your advice and try another cycle.

 

The people who replaced the cells are willing to take a look at the battery pack again but I am a bit cautious in case they make things worse through ignorance. Of course they may come across something but I thought I would try you and Mark first.

 

Thanks again. Tom

[rick_dykstra]

Hi Tom.

 

It's good news that the battery holds its charge. The new cells appear to be OK. If cycling the battery several more times doesn't cause all three lights to fire up and or the battery to advance the motor drive, it would appear that the bq2010 chip is playing up. It has the job of sensing the available voltage from the battery pack, lighting up the lights and telling the camera whether it can motor-drive or not. It was quite thrilling to replace that little chip and see the battery, motor drive and camera start working perfectly.

 

But I haven't given up on your battery yet.

 

As you might have read in the thread above, replacing the bq2010 was not too difficult and would be easy for a solder jockey. (Why don't US folk pronounce the 'l' in solder? ). I found the chip at Mouser Electronics. About $10 each.

 

bq2010 gas gauge chip at Mouser

[TomM]

Hi Rick,

 

I have tried to recharge one more time but ended up with the one light still flashing and nothing else improved. I have no idea why they do not pronounce the "l" either but you might be relieved to know that I do! I presume that a solder 'jockey' is one proficient with a soldering iron. Do you think it possible for someone less than practiced to attempt this? I am reasonably handy with most things. Is there a particularly sophisticated soldering tool that I would need for removing and making small connections of this type? I presume that overheating the chip will simply destroy it. Before I try to remove it, is there a simple test that I can carry out to see whether it is at fault?

 

I will try the discharge/recharge thing a couple more times but my gut feeling is that I am going nowhere with that.

 

Thanks again. Tom

[rick_dykstra]

Hi Tom. I would say yes, a chap who is handy with most things and has good close vision, will be able to replace the bq2010. Only a few simple tools will be needed, which you or a friend might already have. A soldering iron with a fine tip, desoldering braid or a desoldering vacuum kit, a flux pen. Have a look at YouTube for videos on replacing chips and using flux. I found these encouraging.

 

I'll be travelling for a couple of days as of tonight but will check in again as I can and on Wednesday to see how the cycling has gone.

 

Regards, Rick.

[jacobh]

My battery acts strange sometimes too. The charger will go through it's cycle and only one light is lite on the battery. Sometimes I will have to go through several charge-discharge cycles to get all lights on.

 

I have had similar experience. I also had the unit sent back to Leica with a complaint. But they returned the unit after readjustment with the advice that it may need repeated discharge -charge cycles to reach the status with all three LED's lighted. So far this seems to be the correct procedure although I keep feeling there is something not quite optimal with the whole electronics supervisory and control system.

 

Jacobh

[TomM]

Rick,

 

Thank you again. I have run the discharge/charge cycle three more time with no change - it must be a total of thirteen or fourteen attempts now so I think that is not going to be the solution. I shorted across the 3-4 contacts and the single light, instead of flickering, glowed solidly but just the one. For the first time I opened the casing to take a look at it. There was nothing obviously wrong. The battery installation looked a very neat job with the batteries all stuck together and the wiring neat enough. I closed it up, stuck some shim stock between contacts 3 and 4 and tried it in the camera. I ran a film through in double quick time testing all functions including rewind and it worked properly as far as I can judge. I'm inclined to leave it alone and just pull out the short for recharging purposes. Do you agree that this is a satisfactory solution? Looking at the bq2010 I was surprised to see how small it is and how close the contacts are. I'm not sure that I could replace it successfully. Thanks for the link to Mouser - I assume the correct item is the D107 variant.

I would be interested to hear whether anyone else is doing what I propose or whether they have another solution other than replacing the bq2010.

Thank you for all the comments.

Tom

[rick_dykstra]

Hi Tom. I have to agree that it's looking like the battery cycling is not going to be the answer.

 

Can you post a pic of how you shimmed contacts 3 and 4? This could be useful for future reference. From what you're describing it sounds like a similar outcome to my post #88. Great. The trick will be to keep track of the batteries output voltage and to recharge it when it gets close to the state of discharge the bq2010 would normally be monitoring. From post #41 I see that this would be 0.95V x 8 cells or 7.6V. 8V might be low enough.

 

Re replacing the bq2010, it was easier to do than I expected. Fiddly, yes, but the soldering itself went well. If flux is used in the right places (on the board's contact pads and on the chip's feet) the solder settles where it needs to be. The vids on YouTube make it look like magic.

 

The exact bq2010 I bought from Mouser Electronics was:

 

595-BQ2010SN-D107

MFG PN:BQ2010SN-D107

NiCd/NiMh Gas Gauge

Texas Instruments Battery Fuel Gauges

 

It cost 9.63 USD for one.

[TomM]

Rick,

 

I have tried to attach a picture of what I did but as I have not done this before I am not sure how it will result.

 

My shim was a simple device that could be improved, but basically I had some 0.03 mm steel shim stock that you can cut with scissors and fold so I made a 13 mm x 13 mm "U" with 5 mm wide legs, folded the legs to double the thickness then folded their ends to be four times the thickness and tucked these thicker ends under the contacts 3 & 4 on the battery housing, folded the rest of the "U" against the end of the housing and held it in place with electricians tape. The ends seemed to fit quite snugly and because of the 'springyness' of the steel apparently make adequate contact.

 

I think that I will get hold of a spare BQ2010 and perhaps I will find someone to do the installing for me - or not!

 

Thanks for your interest and help. Much appreciated.

 

Tom

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Hallo,

Look here: Interesting Leica gear

[rick_dykstra]

Thanks for the pic Tom. Are you sure you don't work part time for Mythbusters? I've seen your drawings there I think.

 

Please look out for a Private Message - I sent one a day or two ago. If it doesn't turn up, please let me know. They appear up near where your login name is shown. Regards, Rick.