Vintage Synth Explorer Forums

Having worked on a ludicrous amount of cherished vintage studio gear over the past few years I have seen a depressing and really quite alarming amount of carnage to pcbs in very nice kit due to severe battery leakage. This is especially the case where pcb mounted NiCd batteries such as the infamous Varta Mempac were employed.

What is becoming a concern to me is that from the outside most owners could be oblivious to the kind of damage that there is a very real risk of occurring on the inside. Whilst owners are polishing their beloved synths many are blissfully unaware of what is going on inside! Lets face it - it doesn't matter what sort of ritual you think is going to save your beloved old kit from this sort of thing... it needs to be checked out periodically and rectified if necessary!

Some of these batteries are now getting on for 40 years old!

As someone who used to head an electronic design team I find it really quite depressing that so many peer reviewers thought nothing of their guys using rechargeable pcb mounted batteries with a well understood failure mode in so many pieces of studio kit - some of which were extremely expensive! ..and its certainly not just limited to studio equipment - there are a ton of vintage computers also fitted with these darned things.

So for some time now I have wanted to start and maintain a definitive hotlist of what I and other contributors consider to be the most at risk from severe battery damage.

This is what I have so far. I have put these into two categories - firstly those that I consider to be at very real danger of severe battery damage and then those that can be prone to damage if the battery is left long enough in a discharged state. Please note that I appear to be singling out NiCds over Lithium backup batteries - this is because the chances of them leaking and causing severe damage are considerably greater.

..and its certainly not just less expensive/desirable gear either - I have had three AMS RMX-16s in the last few months alone with tracks on their CPU boards completely eaten away by leaking batteries!

At Risk of Severe Damage to PCB due to PCB Mounted NiCd Battery Leakage:

Synths:

• Korg Polysix
  Korg Poly-61
  Korg Poly-61M
  Korg Trident I
  Korg Trident II
  OSCar
  Siel Opera 6
  PPG Wave
  Buchla 400
  Peavey SpectrumSynth
  Peavey DPM-V3
  Gem S2/S3/Equinox
  KAWAI SX-210
  KAWAI SX-240
  KAWAI SX-400
  SIEL DX-600
  ORLA/Böhm DSE 8, DSE 12 & DSE 24
  Böhm Dynamic 4x9

Drum Machines:

• Roland CR-78
  Movement Computers MCS-2 (NASCOM II Computer)
  Böhm Digital Drums
  Linn 9000 (OMG the carnage!!)
  Linn LM-2
  Oberheim DMX
  Oberheim DSX
  Cheetah MD-16
  RSF SD140

Outboard:

• AMS RMX-16
  AMS DMX-15
  Publison IM-90 "Infernal Machine"
  Lexicon M97 Super Prime Time
  Lexicon M200
  Lexicon 224X with Memory Option Board
  Korg SDD-3000

Misc:

• Roland CSQ-600

Risk of Damage through extended discharge:

• Memorymoog (Lithium but now of an age where severe damage to pcb is a very real possibility!)
  Rhodes Chroma (with original CPU board fitted - Drycells can leak onto CPU, front panel and stack pcbs)
  Roland JP-4 (NiCd battery mounted in floor of synth but can lead to corrosion to board through wires)

If anyone knows of any other synths specifically with pcb mounted NiCd batteries then let me know

Hopefully this list can become a sticky for reference.

LIST LAST UPDATED: 30/03/21

Add the Lexicon 224XL memory option board to the danger list for ni-cads with a charge circuit. Has 3 AA with solder tabs.

HideawayStudio wrote: [...] PPG Wave [...]

Oh yes.

Leaking is not the only problem as I had to learn -- those darn VARTA batteries produce corrosive fumes which also eat into adjacent boards.

Stephen

CR78 and CSQ600 sequencer

Dr. Böhm Digital Drums

Stephen

All excellent suggestions... list updated!

I'd forgotten about the Lexicon 224X - I only had one in a few weeks back and I was sufficiently concerned about that one (which had also started to leak!) that I removed the pcb mounted batteries and bolted a battery holder to the side of the chassis and remote mounted a fresh set of NiCds in their place.

SCI Prophet 600?

Mooger5 wrote:SCI Prophet 600?

Most of the Sequential designs including the P600 utilised the larger solder in (often bright yellow) Lithium backup batteries (eg. BR-2/3A). Although these certainly have been known to leak once discharged for extended periods this usually takes a lot longer and so I've not yet made a list for this category. Similarly the solder tag variants of the infamous CR2032 "button cell Lithiums" found in hundreds of synth models such as the DX7 will eventually leak but this often isn't until the batteries are into very old age (or have been discharged unusually rapidly and then left for extended periods - eg. if there is an excessive battery drain due to a fault). It is not at all uncommon to find CR2032s and other variants with over 3 volts still present on them after 25 years in designs where the NVRAM current drain is low enough.

Peavey DPM3.

blueknob wrote:Peavey DPM3.

Many thanks for that - list updated.

Kawai SX-210 has it just like the SX-240.

belltones wrote:Kawai SX-210 has it just like the SX-240.

Many thanks - list updated.

The Emu Drumulator.

Love Canal Craig wrote:The Emu Drumulator.

The Drumulator uses a 2/3A lithium cell and not a rechargable NiCD so thankfully its not so prone to severe leakage.

CR78 and CSQ600