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9000+MD-90+NP-90M question

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roberthansjorg View Drop Down
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Post Options Post Options   Quote roberthansjorg Quote  Post ReplyReply Direct Link To This Post Topic: 9000+MD-90+NP-90M question
    Posted: 20 March 2021 at 16:18
9000+MD-90+NP-90M question

Can anyone help me with a wiring diagram for the Minolta NP-90M battery pack?
I've recently replaced the NiCads (13) for Nimh batteries. The unit works fine but the side shutter release button doesn't.
A diagram of the wiring would be helpful from anyone who has done this job.
 



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neilt3 View Drop Down
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Post Options Post Options   Quote neilt3 Quote  Post ReplyReply Direct Link To This Post Posted: 20 March 2021 at 16:30
It might be worth sending Pete Ganzell a P.M .
Just a long shot , but he's done a heck of a lot of tinkering with Sony and Minolta gear .
He mightught have a copy of the service manual .
Sounds more like you've got a bad joint though , have you ran a test meter over the contacts to check continuity ?
see my photostream on flickr;
http://www.flickr.com/photos/neilt3/
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 20 March 2021 at 23:41
I can't help with your question but I've used nicads and NimH a lot. Nimh often have a much higher voltage after charging than nicads which might upset the camera. Either wait a few hours after charging or try discharging them slightly before use.
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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roberthansjorg View Drop Down
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Post Options Post Options   Quote roberthansjorg Quote  Post ReplyReply Direct Link To This Post Posted: 23 March 2021 at 08:45

Much obliged for the reply.
Sorry for the delay in replying.
I've used my multi meter and I'm getting
16.22v across the terminals on the NP-90M.
I've wired and tabbed up as per the original.
I was quite careful to do that.
My NP-90m forwards the film to whatever setting I
choose to use. Fast or slow. No problem there.
I have a clue why the side button doesn't work yet.
I'll make some adjustments and then let you know what I found
if I'm correct.
Once again - thanks for the input.
Robert

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roberthansjorg View Drop Down
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Post Options Post Options   Quote roberthansjorg Quote  Post ReplyReply Direct Link To This Post Posted: 23 March 2021 at 08:55

Thanks for the reply.
Sorry for my delay in replying.
I replaced the Nicad's with NimH 1.2v 400aH
Zinc tabbed and rewired as per the original.
Did it in stages and took photo's of the original to start.
Put it back together and it works fine.
My NP-90M fore-wards the film as per any setting I choose-fast or slow.
I'm getting 16.22v between the terminals according to my
multi meter.
I've got an idea why the side button doesn't work yet
but I need to make some minor adjustment and if it works then I'll let you know.
Thanks for the input.
Robert
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Post Options Post Options   Quote roberthansjorg Quote  Post ReplyReply Direct Link To This Post Posted: 27 March 2021 at 13:36
Hi,
Just to follow up my previous posts.
The side button on my NP-90M didn't work because I had misplaced the 6 pin
connections on it's face. They are supposed to be positioned sitting on top of the divider steel plate not under it. In other words I'd positioned the pins too low the first time round. Once they were at the right height then a proper connection was made.
My NP-90M works fine now when connected to the winder MD-90.

Changing the batteries on a NP-90M is no easy task. It's certainly do-able
but not for the faint hearted. You have to be able to use a soldering iron carefully and ideally you'd need a mini spot welder as well.You'd have to photograph the wiring once you'd opened the unit. You need precision screwdrivers to do that and the tiny screws are different lengths so you'd have to log that carefully.
The batteries I use are now NimH not Nicad. They are the same size as the originals and took me a while to source from the Component Shop in the UK- at £1 each.
I'm an amateur and for me it was a learning experience. I like to make old things work again.
I know we've all gone digital but my Minolta 9000 still looks good and works fine. It's a well built workhorse.
Probably last me out!

 



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roberthansjorg View Drop Down
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Post Options Post Options   Quote roberthansjorg Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2021 at 15:02


I'm using 13x 1.2v 400maH Nimh batteries in my NP-90M.
I've got a smart charger.
What charge settings should I use to charge this pack?
Any ideas?
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2021 at 16:25
How are you charging them?
If it's a generic battery charger, fast charging in a couple of hours is usually best provided the charger has a decent cut-off. Slow charging Nickel-based batteries ruins them eventually. So does leaving them charged for long periods - which is why non-lithium cordless phone batteries die after a year.

My advice? Keep two sets. Leave one near-flat (10% charge or less) and fast-charge it before fitting into the device. Make sure you swap batteries every month and run the used ones flat, then charge them for a few minutes only and leave them. Don;t leave any batteries except Lithium in devices for more than a month, and even Lithium should be taken out of the device if you don't use it for a month, or they can die too.
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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Post Options Post Options   Quote roberthansjorg Quote  Post ReplyReply Direct Link To This Post Posted: 07 April 2021 at 10:07
Thanks for the reply.

The Minolta NP-90M is an enclosed battery pack with 13 x 1.2v 400mah NiMH batteries in it - zinc tabbed and wired in series.
It locks on to the film winder below the Minolta 9000 SLR.

I'm using a Sevenchip B6 V3 smart charger to charge the pack.

The voltage across the terminals of my NP-90M is currently 17.58 volts.

When I charged this pack the default setting for the charger was 0.1A and I didn't bother to change it this time. The cutoff time was 240minutes and the battery pack was hand warm by then NOT hot.
I can set the charge current to 6.0A if I want.
Can you suggest a cutoff charge?
I don't use the NP-90M all the time so it looks to me - based on what you've said - that I should discharge this pack when it's not in use.
My smart charger can do this as well. Down to what voltage?
I'm still learning how to use the smart charger. It does work but I still need to know the best settings for my pack.
It does "cycle" charging too.
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 07 April 2021 at 13:22
1.0 or 1.1V/cell is fine for discharge. Use a low discharge rate if you can adjust this (0.1A), but 200mA or 400mA for charge.

If you ever find your battery won't make the right voltage on charging, but is (say) 1.2V less, then this can be due to an internal short in one cell due to crystallisation. you can correct this by discharging the pack gently then charging at the highest current you can get to get it hot, which melts the crystals and reforms the cell. But don't do that unless you need to!

NiMH seem better than nicads at low current discharge (and usually have higher capacity too) but sometimes not as good at high discharge rates due to the higher internal resistance.
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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Post Options Post Options   Quote roberthansjorg Quote  Post ReplyReply Direct Link To This Post Posted: 08 April 2021 at 13:06
Hi,
OK- charge at 0.1A,(default) 0.2A 0r 0.4A. I'm sure my smart charger can do this.
Discharge at 1.0/1.1v/cell (my battery pack has 13 cells.

I've only recently changed this battery pack to NiMH and it reads 17.58v between the terminals now. I'm sure that's fine. 13x1.2v is 15.6v anyway.

I notice you're in Bristol. I'm in Nailsworth just north of you.

Best,

Robert
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Miranda F View Drop Down
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Post Options Post Options   Quote Miranda F Quote  Post ReplyReply Direct Link To This Post Posted: 08 April 2021 at 16:41
Ah yes, Nailsworth. Driven through it many times. The longest village/town name in the area with no repeated letters. Beloved of a certain kind of navigational clue-writer!

NiMH cells frequently give a higher charge end-point voltage than Nicads (1.4V+ per cell instead of 1.3V+ after fast charging) so if you ever get an error with freshly charged cells, leave them for an hour or two and they may be okay.
Miranda F & Sensorex, Sony A7Rii, A58, Nex-6, Dynax 4, 5, 60, 500si/600si/700si/800si, various Sony & Minolta lenses, several Tamrons, lots of MF primes and *far* too many old film cameras ...
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