A Small Victory...

Seven or eight years ago, we bought a large-screen HDTV. After doing quite a bit of research on the various technologies and models, we eventually settled on a rear-projection triple-CRT model: the Pioneer Elite Pro-620HD.

It's a monster of a TV. If the inside of the cabinet were hollow, you could use it as a residence for 3 or 4 families in some parts of the world.

We've really enjoyed this television. The picture is superb, and the user-tweakable digital color convergence has allowed us to keep it that way for all these years (I adjust it every 18 months or so).

But a couple of days ago it just quit working. The symptoms were not at all encouraging: when you tried to turn it on, the green power light would come on for a fraction of a second, you could hear some relays clicking, and then it just shut down again.

A few minutes on the web and I learned several depressing things: (1) Pioneer no longer supported this prehistoric model in any shape, way, or form (including at their authorized service centers); (2) nobody has any spare parts for it; and (3) there apparently is no longer any such thing as a television repair shop.

I was on my own.

A few more minutes of searching for our TV's symptoms led me to several articles and forum posts. There I learned that this model had a history of exactly this failure – and that at least for one person, re-soldering some “cold” solder joints on the low-voltage power supply circuit board fixed the problem. I also knew from long past experience as an electronics tech that cleaning dirt (especially away from high-voltage components) and cleaning/reseating connectors could often cure a problem.

So I decided to take the back off the beast and see what I could do. The thing was quite expensive, and I didn't want to just throw it away without even trying.

First came the easy part: cleaning off the accumulated dust of years, and reseating the connections. As I was doing this, I could observe (for the first time, actually) all the electronics in this TV. A couple of impressions: it was very nicely made (trust me, not all electronic equipment is!), and there was an awful lot of electronics. I counted 9 circuit boards in the area I could see, and I don't doubt there were more tucked away in parts of the cabinet I couldn't see.

After the cleaning/reseating, we tested. No joy. The symptoms were identical. So I decided to go for the more difficult task of removing, cleaning, examining, resoldering, and replacing the power supply board.

There are actually two power supply boards in this TV: a low-voltage and a high-voltage board. The low-voltage board was the culprit in the article I'd read online, and fortunately it was the easier of the two to get out. The board is mounted vertically at the extreme right side of the cabinet, as you're looking in from the back. There were 17 screws and 11 connectors to remove, and then out it popped. Took only a few minutes to get it out.

Then I took it to our kitchen table, and carefully examined it in the bright sunlight. It was a largish (about 12 x 18 inches) single-sided circuit board with dozens of large, high-power components on it (all of this is typical for a power supply). Right away it was obvious that someone had worked on this board since it was manufactured. The giveaway was that 30 or so solder joints had brown rosin residue remaining – something you don't see on boards that were soldered by machine (the rosin all gets cleaned off with solvents). A little more examination and I saw a pattern: the resoldered joints were larger than the majority of the joints. That led to a theory on my part: that Pioneer had a manufacturing problem that caused cold solder joints on the larger joints on the board (and being a power supply board, it had quite a few of these). Larger solder joints do require more heat, and they are tricky to get right in an automated soldering machine, so this was at least plausible.

So I resoldered every one of the large solder joints on the board – something like 175 of them. The hardest part of this chore was spotting them – my eyes don't seem to work quite as well as they used to. I've done a lot of soldering in my day, and apparently I didn't forget how (it's like riding a bicycle, you know). In the course of carefully looking for each of those large joints, I spotted 3 that looked like they might be cold solder joints, and one definite bad joint, complete with cracks.

When I finished all the soldering, we put everything back together and tried it out. Much celebrating ensued – the danged thing worked, and it has kept on working. Debbie (the primary consumer of TV around here) was very happy to have her TV back, and we were both very happy that we didn't need to go out and buy another TV.

A small victory, to be sure...but it really does feel very good to have had it!