Need Help Building JP1.x from jherrick

tommyj2006 · Post by **tommyj2006** » Sun Jan 13, 2008 4:37 pm

I received this kit from my aunt as a gift, and have attempted to build the interface based on the pictures from jherrick's thread in the marketplace. I am not by any means the best at soldering, but I think my points are good enough to get the job done. What I am most concerned about is the orientation of the components on the board. Here is what I am experiencing:

1. The remote stops working after I plug in the cable
2. The computer does not recognize a JP1.2 or JP1.3 remote
3. Comtest detects activity on the serial port when I plug in the remote or unplug the remote

I am new to all of this, so bear with me. If you need any more information, just let me know. Worse comes to worse I will just get a pre-made cable.

Again, not the cleanest (VERY shaky hands, definitely not surgeon caliber)

Thanks for any help!

Tom

Tommy Tyler · Post by **Tommy Tyler** » Sun Jan 13, 2008 8:08 pm

Orientation of the two capacitors, the resistor, and the two quad resistors is not important. But I see no markings on the IC, and so I'm wondering how you know which is pin 1. Also, there looks like a lot of solder between the quad resistor pins toward the cable wires. Are you sure some of those pins are not shorted together?

tommyj2006 · Post by **tommyj2006** » Sun Jan 13, 2008 8:20 pm

I am fairly confident that there are no shorts there, but I will take up some of the solder and see if I can't clean it up a bit. The markings on the IC have worn off for the most part, but are visible at the right angle. From what I am seeing, there is no distinguishable way to see what would be designated as pin one, so perhaps I should try turning it around. Got any good tips for getting it off?

Thanks for the reply!
Tom

[EDIT]
On further investigation, it seems pin one may be at the upper-right corner. Should it be the other way around?

Evan_s · Post by **Evan_s** » Sun Jan 13, 2008 8:28 pm

looks to me like there's a dent on the IC on the left side which I believe should mean pin one is the bottom left pin.

Tommy Tyler · Post by **Tommy Tyler** » Sun Jan 13, 2008 8:47 pm

To remove the IC, first remove all the solder from the pins. The best way to do that is to hold a piece of solder wick down on the pins with the tip of your soldering iron, and slide the wick along as it picks up solder. When you can no longer see any thickness to the solder, the pins will still be stuck to the pads on their bottom surface. Place the tip of a straight pin under a corner pin and pry up very gently as you touch the soldering iron to the pad beyond the end of the pin. You'll hear a slight "click" when the pin pops loose from the pad. Remove the iron immediately so the pad will cool and not grab the pin again. Move to the next pin, and repeat the procedure all the way down the line. Then do the same for the row of pins on the opposite side. If you can't understand anything about what I'm saying, it means you are in over your head, and need to find a technically qualified person to help you.

tommyj2006 · Post by **tommyj2006** » Sun Jan 13, 2008 9:29 pm

Great suggestion, I was able to get the chip up no problem. Unfortunately, my computer just dumped on me so I can't get a better picture of the IC. The numbers (which can't be seen in the pictures) are oriented in the picture such that the top of the letters point 'down' toward the cable, if that gives any indication of where pin 1 may be. Which way should it be oriented?

tommyj2006 · Post by **tommyj2006** » Sun Jan 13, 2008 9:46 pm

Ok, well I got my computer up again (some bad RAM apparently) and I tried scanning the IC. Its fuzzy, but this should give you an idea of what it looks like.

Previously, the logo (I think?) on the lower-left was in the upper-right of the first photograph.

Tom

jherrick · Post by **jherrick** » Sun Jan 13, 2008 9:57 pm

tommyj2006 wrote:I am fairly confident that there are no shorts there, but I will take up some of the solder and see if I can't clean it up a bit.

Tom,
yes, clean that up around the resistor networks. I have found that a multimeter is a great tool when dealing with those concave networks. They are really designed for wave soldering, so to use them with an iron canbe tricky. Sometimes you think you are touching the pad and resistor at the same time, but don't. This can cause them to be an open. Other times you use a little overkill and short two together. Clean it up and check it with a meter if you can. But that it not the most obvious problem.

The markings on the IC have worn off for the most part, but are visible at the right angle. From what I am seeing, there is no distinguishable way to see what would be designated as pin one, so perhaps I should try turning it around. Got any good tips for getting it off?

Thanks for the reply!
Tom

[EDIT]
On further investigation, it seems pin one may be at the upper-right corner. Should it be the other way around?

This is the most obvious problem. As you have discovered, Pin 1 is on the upper right, and should be lower left. Here is a picture to help identify Pin 1 when there is no indent in one end and no dot screenprinted on the IC.
Jim

tommyj2006 · Post by **tommyj2006** » Sun Jan 13, 2008 11:45 pm

Thanks for the info! Well, I have checked and checked and checked and cleaned up all the points, but no go. When I plug it into a remote, it stops responding to key presses. When I unplug the cable, it flashes twice. I don't know what else to look at.

Tom