Panasonic NV-M3500 VHS Video Camera and a 5 minute battery hack

February 8, 2016 12:30 pm Published by

Disclaimer: whatever you might do looking at this post, you are doing at your own risk. Batteries are chemistry plus electricity, thus, twice the danger — not only you could get electrocuted, but you could also set yourself on fire or something, if you don’t have the necessary proficiency. All the information here is provided for educational purposes only.

(Yeah, it’s been a lot of posts about batteries here recently 🙂 )

I’ve wanted a VHS camera since a long time ago and recently a chance turned up to get one, a legendary Panasonic M3500.
However, it had no power supply, and the original battery didn’t work too.
When I used some PLS wires to connect to the ⎓ jack at the back, all I got is a No Battery icon and then the camera switched off for no reason.

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Looking at the schematic it seemed that the battery input is directly wired to the ⎓ input, except for that when a power supply is connected, the battery is disconnected and some kind of voltage regulator is bypassed (hence the NOREG title).

With the fact that my improvised-bench-PSU is old and puts out just 11.7v on the 12V rail, and that the PLS wires are so thin because they were meant to carry arduino signals and not power cameras, it’s time to crack this thing open and connect directly to the battery input.

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Sure enough that got rid of the power off issue, and with minimal mechanical fixes it was up and running in no time, playing movies off my old VHS tapes. Didn’t even have to replace the belt this time! That’s good because speed adjustments are a pain in VHS machines 🙂

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However, running off a bench PSU pretty much ties you to a range of roughly half a meter around your nearest mains socket. After some minutes of intensively trying to come up with pretty much any portable 12-volt power supply, my sight dropped onto a fake MacBook Pro battery I got from AliExpress a couple months ago. It was never properly working in the computer for some reason, instead overheating to over 60ºC and shutting off the laptop at random battery levels, not to mention the capacity always appeared different in System Profiler. Apparently the cells’ C-rating and the computer’s power consumption are mismatched, so I stopped using it as a laptop battery for safety. On the other hand the camera uses quite much less power so…

Using some Extreme Care I’ve added two alligator clips to the aforementioned battery.

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Soldering near LiPoly batteries is always a risk, especially if you don’t have a decent soldering iron, so extreme care was a must 🙂

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The first thought was to just use sticky tape to put it onto the camera. Even though that worked, and I was able to do a few shots that way, it seemed flimsy, debalanced the camera, made it heavy and the exposed electronics made it a bit dangerous to use in open spaces or where battery-illiterate people might come up to it 😉
Not to mention that the exposed clip connectors made it impossible to charge the battery in the laptop because they could easily short out to the laptop case.
Why didn’t the battery respond when I just connected it to a 12v PSU is a question from a different kettle of fish…

After some bits of thinking… PC peripheral connectors to save the day!

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Replaced the alligator clips and shortened the wires a little bit…

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Not shown — some hot glue to keep the wires in place just in case they come off so they don’t mess anything up in the battery.
Sticky tape to cover the thing up 😛

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Added the matching connector to the camera, and made a 5m extension cord… and sure thing, it works fine! I can charge the battery pack in the MacBook and then use it with the camera. Plus I can throw it in my backpack and still use the camera with such an extension cord, especially if I put that on a spring-loaded reel.
And when filming indoors, I can use any PC PSU because the pinout matches the standard connector!

Quick 10-minute hack, bringing the electronic masterpiece back to life 🙂

Now all I need is some VHS tapes and an AV to USB dongle…and something to film, obviously

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