Thursday, April 26, 2018
Publication Date: 10/1/2008
Archive >  October 2008 Issue >  Tech-Op-Ed > 

Waiting for the PC Board
Walter Salm, Editor .
All too often, my knowledge of our industry — the manufacture of electronic products — intrudes on my personal life. We were parked at an RV service center in Oklahoma City, while Roger, the proprietor, carefully peeled back the well-dried-out caulking that had held our basement air conditioner/furnace cover in place for five years. He ever-so-carefully removed the plastic, vented cover.

Then he opened the weather-sealed metal cover on the control compartment, revealing the rather complex printed circuit board. He examined it carefully, and then pointed out to me three areas where resistors had been fried. "This is why your air conditioner and heat pump aren't working," he said. "And this same board controls your gas furnace, too." Bingo. He had found the problem. Getting a replacement board was another matter.

He got on the phone with his Coleman distributor and was told that Coleman hadn't manufactured that particular circuit board in five years. They could make one, but it would take about two weeks. The Coleman distributor's answer was not encouraging news. After many years in this industry, I could well imagine what it would cost to recreate a legacy PC board, quantity one. And waiting for two weeks in the RV repair facility's yard was likewise not high on my list of desirable activities. True, we were given 50-amp power and fresh water hookups, and the use of a dump station at the opposite end of the yard, but this was not my idea of any way to spend 14 days.

I looked at the board, which was 100 percent PTH — very old technology, complete with five made-in-China P&B relays soldered in place — and thought, "Gee I could get those resistors at Radio Shack and rework this board myself." But I had these thoughts with the full realization that there was very likely a blown diode or IC or two that had caused the resistors to burn out in the first place, or maybe fused relay contacts, and without a full diagnostics setup, there was no way in the world that I could do this.

So I got on the Internet, and then on the phone, exploring my contacts in the RV world, and came up with some serious information. After some exploration, I found what purported to be a replacement circuit board for my Coleman basement unit from a supplier based in Houston. The price: $318, way better than the thousands that I had imagined for building a single board from scratch.

A little more exploration (this took a couple more days, waiting for return phone calls) and I knew that my problem was solved. Another source offered the board for $290, but then I found that these boards were really revision "C". My burned-out board, was version "A". The latest version was a drop-in replacement requiring "a few simple wiring changes." Full instructions would be included in the package. And I found a source that supplied it for a mere $149. Wow, now we were cooking.

Even though the board only had to travel to Oklahoma City from Kansas, it took four more days, with the weekend accounting for two days. UPS just doesn't like to deliver on Saturdays, FedEx was not in the picture at all for this supplier, and as it turned out, it wouldn't have made any difference anyway.

The board arrived, and soon Roger had it installed. The "simple wiring changes" for the "C" board were anything but. Fortunately, Roger was easily up to the challenge, and soon our heat pump was running, something it had not done for a couple of months. But we weren't out of the woods. It turned out that our wall thermostat was also defective. It was actually the second one since the thermostat had been an ongoing problem. So thermostat number three was ordered, and more waiting for delivery. In the meantime, we had a chance to visit the Oklahoma City National Monument and museum — all very tastefully done, and of course we learned where all the shopping malls were. While there, we were treated to the lowest fuel prices in the entire U.S.A.

While all this waiting was going on, naturally, we were working on this issue of U.S. Tech, since we were in fact residing in our home/office (on wheels). We had two electric heaters to keep us warm while waiting for the furnace repairs to be completed. I took a good look at the "C" board when it arrived, and it was still 100 percent PTH. I guess I had been expecting a slimmed-down streamlined surface-mount board with all the latest and greatest. It just proves the oft-stated adage that PTH is just fine — in its place. The facility: Price RV Repairs in Oklahoma City, and they were simply flat-out fabulous.  

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