That happened in my McIntosh MAC4200 Stereo Receiver I purchased off of ebay. When I checked it out, the 3 AA size NiCd Battery Pack had failed. It ate the paint under the Battery Holder plus the Paint and Primer down to the Bare Metal. It had also crept for at least 1” beyond the foot print of the Battery pack. And yes, the leaking wicked down the lead wires onto a circuit card causing connector damage, it ate a couple of traces and left crud on the board. Lots of FOD and work to clean it all up and fix it.

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I replaced the whole NiCd Battery Pack with a 4 Farad 5.5V Super Capacitor. It was mounted to a G10 Prototype board. I pre-charged the Capacitor before connection. I also replaced the charging Resistor with a higher value and wattage for when it had power disconnected for long periods or a power outage for days (which I tested – our power is very stable, maybe a power loss for a couple of hours per year).

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There was already a reverse current Diode in the circuit so, I didn’t need to add one. The Memory-Hold Voltage Range was 3.0V minimum – an important data point because a Capacitor discharge curve is different than a NiCd, but similar enough to allow the change. I also made sure the +5V Power source was healthy (Bridge Rectifier, Regulator, well heatsinked and new 105C Bulk Capacitors) to avoid any future concerns.

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Not original, but has worked well now for almost 5 years, it is designed to be reliable and safe. I know it won’t happen again.

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Here is a picture of the modification before I cleaned everything up.

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All of the above items need to be investigated to make sure that what you are doing is in the best interest of any equipment modification and safety. Some people, as it has been stated before, replace rechargeable battery packs with other types of batteries (I have seen NiMH packs or Alkaline packs blindly replacing NiCd Packs before), again, you need to understand what you are doing.

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Relocating the pack, packaging it, isolating the lead wires and doing the other provisions mentioned in the original post and other response posted are really good ideas.

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Ross

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Oh, and a sad tear for the damaged Watkins Johnson Receiver. Very good equipment.

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I used a few WJ-8999s and worked on one to repair it, too. Now, that is a very packed receiver. Both boxes are really packed with little room to spare.

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Ross

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