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Newbie story: Building a CTB-16PC (seemingly without reading the installation manual)


Steven
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My coworker was suitably impressed with my display, so a couple of years ago he decided to make his own 16-channel display on his new home. He bought the package with the CTB-16PC kit.

After a few months I asked him for his progress, but he hadn't started on it yet. Then, one day he told me it was finished, but it wasn't working so could I help him fix it. So after a few weeks of reminding, he finally brought the unit in.

The problem was the worse I expected: He neglected to use the socket for the CPU, and he installed it backwards. As we all know, those things are impossible to de-solder, so I helped him cut all the leads, remove the pins, and clear the holes. He then soldered the socket and got another one from LOR support.

So he finally brought it in today. Upon first look, I saw that the socket wasn't actually soldered, but was just plugged into the board. So we found the cheap soldering iron we keep around the office in the cabinet and I soldered it in.

Next, it was time to install the jumpers. Then I discovered item #2 that was installed backwards, or this time, upside down. He had put the jumpers with the long leads down into the board, leaving short pins that did not hold the jumpers. This problem was solved by removing the voltage-select jumper and inserting a couple pieces of wire. The reset pins were heated up so that they would move through the plastic, and extended tall enough to hold the reset jumper.

Then, came power on. No LED. I checked voltages and everything looked OK, then I checked the voltage on the LED. The meter jumped up and down ever second. So, I asked: "Could you have installed the LED backwards?" The answer: "I didn't know it mattered."

So we removed the LED (backwards mistake #3) and reversed it. Power applied, LED blinks!

Next came the communication test. The hardware utility talked to it, and was able to set its ID to 01. Finally, the light test, but no lights. So I looked carefully. Sure enough, the opto-isolators were installed backwards.

The good news is that they can be un-soldered, and being installed backwards does not destroy them. We reversed one, and now he has a controller that works for 1 channel. I will leave the rest to him.

Let's go over the mistakes:

  1. CPU soldered in backwards
  2. LED soldered in backwards
  3. Jumpers soldered in upside down
  4. Opto-isolators soldered in backwards

The good news is these mistakes can be repaired. So don't worry over minor construction mistakes. And read the installation manual!

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That could be funny, in a morbid kind of way. Wow! I'm glad he has a great friend like you to bail him out.

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Well if the person has no knowledge of electronics or soldering components these are all very common errors.

Unfortunately sometimes those errors can be very detrimental to the assembler when they plug power in, some components being in backwards can be damaged.

Believe it or not most are internally damaged, I forget the actual name, been a while, but believe it's called a latent damage where the component, in time, will break down and fail from being powered up being installed incorrectly or from a static charge. Even though the component may not look damaged, it is and requires very expensive and specialized tools to verify the damage. It also could cause the component to explode, which could cause shrapnel from the component to hit and embed into your body anywhere.

It's why we were always required to wear protective goggles and clothing when we soldered anything, and especially if we were going to power it up outside of an enclosure.

I've seen my share of exploded components of all kinds, resistors, capacitors, IC's, LED's, etc. I've also been knocked on my kiester a few times inspecting others work, powering the unit up only to find it was wired wrong and got zapped by it. Fortunately it wasn't much voltage, but enough you bit you.

Some folks even if looking and reading the manual during assembly would still make these same mistakes, usually newbies that had never worked on this type stuff.

So before I would plug anything in using 120VAC or more, I make darn sure it's correctly wired first and all components in their proper orientation and correct place.

I can't even count the number of times I've had to rework a board someone did where the terminals were installed upside down or on the wrong side of the PCB! That's one of the most common mistakes I saw as a repair tech at the wide assortment of electronics companies I worked for over the years, and usually always made by a new employee, occasionally an old timer would make that mistake.

It's also why I only buy the complete CTB16PC controllers now. Just can't do the soldering anymore like I used to with my current vision issues.

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Your co-worker should live by a simple rule...whatever he thinks is right, reverse it and it will be.

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Its a case of leave it to someone who knows what they are doing and obviously the person didn't.

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Steven,

I can only imagine your patience with your co-worker.

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I'd laugh too....but I did #2 on my first kit. Lucky you guys on the forum caught it.

I'm going to laugh but I laugh because I've been there.

And "YES" he probably didn't read the instructions. which I did and still screwed up.

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