This week I've had two machines come in; a Marshall JMP-1 and a Sequential Circuits Prophet 5 (yes, you read correctly). One was just in time and prior to battery leakage. Unfortunately the other arrived too late and had suffered considerable battery acid damage.
Last week I received a call from someone who had just bought a Marshall JMP-1 and, after stumbling across my article on Marshall JMP-1 Service while doing a little research on-line, decided to send me his new purchase for a once-over.
I got a shock, when I opened it as the battery was right on the point of popping. This was incredibly lucky. With a date of manufacture of 1992, the battery was the original, as fitted in Marshall factory, twenty-eight years ago!
After quickly removing the battery, I tried to take some macro pictures to show swelling. If you look closely, you might be able to see what I'm talking about. The top of the battery should be flat.
I analogise battery check-up with home security; most of us consider investing in CCTV or an alarm system after an incident! Stuart took the initiative and sent me his JMP-1 shortly after he bought it.
Unfortunately the owner of the Sequential Circuits Prophet 5 wasn't so lucky. Apparently this machine had been stored in a case since it was used with Roxy Music over thirty years ago.
It's incredibly sad to see horrendous battery acid damage on the inside of such a beautiful example of this legendary machine.
Many components and quite a bit of PCB tracking are damaged but I'm going to try my best to fix this. Having said that, I've already informed the customer that things aren't looking good.
So, I urge anyone who's buying vintage gear to get the memory back-up battery checked. I also strongly advise all, to regularly check the memory back-up battery in your equipment. Battery acid damage is a terrible thing and can cost a fortune to put right, if at all even possible.
My Live Forever battery mod which is available for most synthesisers, keyboards, effects processors, etc, doesn't just replace the factory fitted battery with something more substantial but if possible, I also move the battery off the main PCB.
Aurora (for the Roland MKS-80) and Supernova (for the Roland Juno-106), are a couple of switched-mode power supplies that I make and that are either available ready assembled or can be installed by me. I recently released Aurora Board Bx, an option that includes a remote memory back-battery and Super Nova was designed with fully integrated remote memory back-battery facility.
I'm currently designing power supplies for several other machines and I'm including the same remote memory back-up battery facility on all of them.
A WORD OF REASSURANCE
Back-up batteries aren't just wired to memory chips. There's always associated circuitry which depending on the age of the machine, the manufacturer and so on, can do several jobs such as switch between battery and PSU power when the unit is switched on and off, provide current limiting and reverse polarity protection.
Since my Live Forever battery mod connects directly to the original back-up battery connection points, any components or circuitry associated with the memory back-up function remain untouched and fully active. As far as your machine's concerned, nothing's changed!
UPDATE - 22nd July 2023
I often get asked about the memory back-up battery in the Marshall JMP-1 and with soldered batteries not really being in fashion anymore, replacements are difficult to get hold of. I therefore decided to knock up a small PCB that mounts into the original battery location but which has a CR2032 clip. This allows for easy battery changing with a standard (you guessed it) CR2032. Measuring the voltage on the battery is a little easier, too. 🙂