Workbench readers are sharp!

Reading our tip about eliminating battery corrosion, a number of readers looked closely and saw that the corroded batteries were not carbon-zinc or lead-acid.

Longtime San Francisco market engineer Bill Ruck writes that baking soda is the traditional choice to clean corroded batteries, but only for carbon-zinc or lead-acid types. These have an acid electrolyte, neutralized by the alkalinity of the baking soda.

NiCad and manganese dioxide batteries have an alkaline electrolyte (and thus are called alkaline batteries). Although baking soda will work, the fastest way to clean up corrosion here is with a diluted acid.

Vinegar fits the bill. The cheap stuff works fine; Bill says he wouldn’t waste his balsamic on such a task. (For a list of things you can clean with white distilled vinegar, see tinyurl.com/wbvinegar2.)

If you can isolate the battery compartment, just pour some vinegar and then scrub with the toothbrush. If there’s a chance the vinegar may get on other components — for instance, if the battery compartment cannot be separated from the equipment — apply with a cotton swab. This takes longer but you end up with nice shiny clean contact terminals.

Whether you use baking soda or vinegar, clean the contacts with fresh water, and dry thoroughly.

Fig. 1: This is one of two sockets to be rebuilt.

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I missed Leon Amstutz, CBRTE, at the recent Indiana Broadcasters Association Annual IT/Engineer Workshop.

Leon is with Taylor University in Upland, Ind. As with Bill’s cautions, Leon sent me a note about the vinegar and alkaline battery corrosion problem (he prefers white vinegar).

After cleaning up corrosion debris that had spilled onto a printed circuit board, he coated the damaged portion of the board with clear fingernail polish. This resealed it against future spills.

Bill is part of a group that is tackling component corrosion head on …

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Fig. 2: The RCA T3 PA cabinet.

… as part of a group of engineers who are refurbishing an old RCA T3 transmitter. This is a 20 kW HF model. The sockets had to be completely disassembled and rebuilt, as seen in Fig. 1.

After a good soaking in ammonia, things looked a lot better. Just as vinegar works wonders on battery corrosion, ammonia helps you overcome salt air’s corrosive effect on silver-plated parts.

Note the round cylinders around the perimeter of the socket; they are actually screen bypass capacitors! The end caps on the capacitors were so rusted that they were replaced with new ceramic caps and hardware, to make things fit and sparkle.

Fig. 2 shows Bill next to the PA assembly. Several panels were removed to facilitate cleaning. What a beautiful result when everything is completed. Everything was stripped from the transmitter, down to the bare metal frame.

Fig. 3: LEDs, top, provide a quick visual indication to identify which transmitter is ‘on the air.’

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Here’s a neat tip that doesn’t cost a lot of money.

How many times have you rushed to your RF site after a failure, only to find both transmitters running, one into the antenna and one into the dummy load? It takes a moment to figure out what’s going on, doesn’t it?

Greater Media Boston has a simple yet effective solution, seen at the top of Fig. 3. The string of green LEDs gives you a quick visual indication as to which transmitter actually is on the air.

Contribute to Workbench. You’ll help your fellow engineers, and qualify for SBE recertification credit. Send Workbench tips to johnpbisset@gmail.com. Fax to (603) 472-4944.

Author John Bisset has spent 43 years in the broadcasting industry, and is still learning. He is SBE Certified and is a past recipient of the SBE’s Educator of the Year Award.