In a case like this, if I do not have the correct removal cartridge or attachment for the soldering iron and I do not have a knife attachment long enough to lift one side at a time, I will cut each of the leads off of the package. For an SOIC like this, a nice fine-tipped pair of diagonals will do fine to snip each leg one-at-a-time. For a package with smaller leads, like a TQFP, I use an exacto knife and shear the leads off against the package. The part is broken, so there is no harm to destroy it to make getting it off easier. Just be careful not to put stress on the pads on the board, so cut up close to the package. Once the leads are free and the package removed, then just solder wick will do the trick to clean up the pads and pick up the leads. A pair of fine-tipped tweezers will snag those dry ones that won't adhere to the wick. Just be careful not to lose a lead, which is why I always prefer doing this work with the PCB removed from the equipment, so no debris will find its way into some inaccessible part. You can use tape, sticky side up, to also grab any pieces that want to jump and try to run away. Having the PCB out of the equipment also makes it easier to clean because I have no idea what flux was used to assemble the PCB, so I want to clean it well after desoldering even though my repair flux is no-clean. This also helps to ensure that there are no pieces of debris, solder balls, or missing wrenches lost under some component. Another suggestion that might help you is that while making videos of your work, take advantage of the video process. I record many things I take apart on video or with pictures, just in case I don't remember how it should go back together. It really helps with the rear drum breaks on a GM truck, and given some of the compact radios and test equipment today, them too. Since you might be a few years older than me, and I need such help to remember things, I suspect you may see the value in this, too. So, recording is often very useful even if we don't make UA-cam videos. Also, when it comes to soldering and desoldering small components, I often need a microscope. Most of the time, my microscope is just a high-resolution camera, and the video output from the camera is fed to a computer with a large monitor. While I am working, my eyes are mostly on the monitor, and recording the process makes sure that nothing goes wrong so that I don't need the recording later. I got used to working this way when my eyes were still pretty good, so now that cataracts are making everything more fuzzy and my lenses are too hard to focus on anything closer than 3 foot away, I can see the smallest of features and ensure my soldering is smooth and has the correct fillets. In making videos for others, if you use the monitor to see what you are doing, you will naturally keep your hands out of the shot and the work at hand in the shot, and thus improve the recording results because we will see what you saw. This is a great series on this IC-746 repair. It is helpful for everyone to share in your process. Thanks for bringing us along!
Different approach with dual inline packages is to hack the pack with a cutting tool, leaving mostly just the leads to be desoldered. Caution: I'm a Mechanical Engineer!
Use much flux. Apply a little Chip Quik to your iron and move it around the pins. Chip Quik MUST mix with the solder (alloy) to reduce the overall melting point. If you wind up with too much, use solder wick to remove it and begin again with Chip Quik. (In fact, you could begin by removing excess high temp solder before applying Chip Quik.)
I'm usually using a tweezer type iron with the right sized wings fitting exactly over the pins. All other tools could damage the pads or blowing away external parts.
This reminds me of one of my early attempts at smd repair. It was a laptop with a bad serial port - the TX data line was stuck high. I tried to replace the line driver chip, a 14288? - I think. Wound up ripping pads and traces off the board. I fixed it without solder or an iron, and had no hot air gun. I used conductive paint and epoxy. I painted new traces and pads and glued the chip to the pads with the epoxy. Got it going. I used this method of repair when I was backed into a corner, and forced to work on smd.
The glue is a complication but I have had luck using a sharp cutter and cutting the legs at the chip body first. Then remove the body and individually remove the legs.
While you were doing yours I was thinking about how to remove my own..so I came up with using a new razor blade and cut the leads off the old part, which left very tiny pieces on the board, which a soldering iron took off easily...
Sometimes, because I have fancy equipment, now, I forget the soldering basics... I was screaming "cut the IC pins and remove the stubs with a soldering iron." Yeah, I have gone the long route, plenty, myself.
What amazes me is this radio failed just by sitting in a box for 20 years! Makes me wonder if this little driver chip didn't fail because some other part in the circuit (like a cap) failed.
...already seen parts1,2,3. You decided to replace this IC without previously measure its output, although you have all necessary instruments to do that. After that you could drive the PA board with your SSG to determine if PA itself was the issue. I've replaced a uPC1678 in the past very easily using chipquik desoldering alloy.
In a case like this, if I do not have the correct removal cartridge or attachment for the soldering iron and I do not have a knife attachment long enough to lift one side at a time, I will cut each of the leads off of the package. For an SOIC like this, a nice fine-tipped pair of diagonals will do fine to snip each leg one-at-a-time. For a package with smaller leads, like a TQFP, I use an exacto knife and shear the leads off against the package. The part is broken, so there is no harm to destroy it to make getting it off easier. Just be careful not to put stress on the pads on the board, so cut up close to the package. Once the leads are free and the package removed, then just solder wick will do the trick to clean up the pads and pick up the leads. A pair of fine-tipped tweezers will snag those dry ones that won't adhere to the wick. Just be careful not to lose a lead, which is why I always prefer doing this work with the PCB removed from the equipment, so no debris will find its way into some inaccessible part. You can use tape, sticky side up, to also grab any pieces that want to jump and try to run away. Having the PCB out of the equipment also makes it easier to clean because I have no idea what flux was used to assemble the PCB, so I want to clean it well after desoldering even though my repair flux is no-clean. This also helps to ensure that there are no pieces of debris, solder balls, or missing wrenches lost under some component.
Another suggestion that might help you is that while making videos of your work, take advantage of the video process. I record many things I take apart on video or with pictures, just in case I don't remember how it should go back together. It really helps with the rear drum breaks on a GM truck, and given some of the compact radios and test equipment today, them too. Since you might be a few years older than me, and I need such help to remember things, I suspect you may see the value in this, too. So, recording is often very useful even if we don't make UA-cam videos. Also, when it comes to soldering and desoldering small components, I often need a microscope. Most of the time, my microscope is just a high-resolution camera, and the video output from the camera is fed to a computer with a large monitor. While I am working, my eyes are mostly on the monitor, and recording the process makes sure that nothing goes wrong so that I don't need the recording later. I got used to working this way when my eyes were still pretty good, so now that cataracts are making everything more fuzzy and my lenses are too hard to focus on anything closer than 3 foot away, I can see the smallest of features and ensure my soldering is smooth and has the correct fillets. In making videos for others, if you use the monitor to see what you are doing, you will naturally keep your hands out of the shot and the work at hand in the shot, and thus improve the recording results because we will see what you saw.
This is a great series on this IC-746 repair. It is helpful for everyone to share in your process. Thanks for bringing us along!
Never easy working in tight spots, great video, thank you
Different approach with dual inline packages is to hack the pack with a cutting tool, leaving mostly just the leads to be desoldered.
Caution: I'm a Mechanical Engineer!
The shearing force can rip the pads from the board. Unless you have really steady hands and a very sharp cutter
Use much flux. Apply a little Chip Quik to your iron and move it around the pins. Chip Quik MUST mix with the solder (alloy) to reduce the overall melting point. If you wind up with too much, use solder wick to remove it and begin again with Chip Quik. (In fact, you could begin by removing excess high temp solder before applying Chip Quik.)
I'm usually using a tweezer type iron with the right sized wings fitting exactly over the pins. All other tools could damage the pads or blowing away external parts.
This reminds me of one of my early attempts at smd repair. It was a laptop with a bad serial port - the TX data line was stuck high. I tried to replace the line driver chip, a 14288? - I think. Wound up ripping pads and traces off the board. I fixed it without solder or an iron, and had no hot air gun. I used conductive paint and epoxy. I painted new traces and pads and glued the chip to the pads with the epoxy. Got it going. I used this method of repair when I was backed into a corner, and forced to work on smd.
The glue is a complication but I have had luck using a sharp cutter and cutting the legs at the chip body first. Then remove the body and individually remove the legs.
While you were doing yours I was thinking about how to remove my own..so I came up with using a new razor blade and cut the leads off the old part, which left very tiny pieces on the board, which a soldering iron took off easily...
Sometimes, because I have fancy equipment, now, I forget the soldering basics... I was screaming "cut the IC pins and remove the stubs with a soldering iron." Yeah, I have gone the long route, plenty, myself.
Great job..fun watching...
An 8 parter... Still a way for us to go - nice way to keep up the suspense.
Check the drivers. They usually short on this radio
You mentioned that you made a video of your 250 dummy load with the probe output. What video number is that. I could not find it
ua-cam.com/video/tQ381HfpAxM/v-deo.html
Kapton tape was my first thought.
What amazes me is this radio failed just by sitting in a box for 20 years! Makes me wonder if this little driver chip didn't fail because some other part in the circuit (like a cap) failed.
...already seen parts1,2,3. You decided to replace this IC without previously measure its output, although you have all necessary instruments to do that.
After that you could drive the PA board with your SSG to determine if PA itself was the issue.
I've replaced a uPC1678 in the past very easily using chipquik desoldering alloy.
Calm down. Both the 1678 and PA are bad. Keep watching
i see you measuring in db,,,rf power does you com monitor have watts ?
yes
Measure the resistance of the potentiometer
ALC is limiting the power. You should see full deflection of ALC on full power.
You used chip quick wrong.
Can’t see a thing
Would be nice if we could see what's going on!
Yup not great at all this vid
Wow
I'm sorry but I didn't learn anything from this video. You were mostly struggling to remove and replace the chip.
I'll give you your money back. The video is my journey. With things so packed in it was very hard to maneuver and not desolder other things.
Out of frame!
How old is this guy? He should be familiar with old methods to remove a part with more than two legs without ruin the pcb. That's no NASA science.
I've removed many SO8 part before. this one happened to give me trouble. probably because I was filming
out of frame. hands in the way otherwise ok