Need advice on installing an 8 pin IC Socket

[ENB]

I need to replace the IC Chip that drives the reverb on my Fender Hot Rod Deville. I would like to install a socket for future replacements. I have read the thread here that describes how to do this, it was helpful. I have an old but reliable weller soldering station that operates at plus or minus 750 degrees F. with the tips I have. So far I have not burned up anything "Yet".

I also have desoldering braid and have limited skills in solder removal with that. If I were to buy a desoldering tool from Radio Shack (45 watt) iron on it, is that too much heat or to eratic of heat to use on desoldering the cut IC pins from the circuit board? I have heard good and bad about solder suckers, so I am a little leary.

ALSO What is the very best reccomended solder for working with circuit boards and size?

Thanks in advance,

ENB

[Robert M. Martinelli]

Hi,
well, the key factor is not the soldering iron power, the key factor is how long you keep the soldering iron tip on the components' pins. As you know power is only the rate at which energy is being supplied, and actually 45W means 45 Joules per second, this means that each second 45 joules of energy ( heat in our case ) pass from the soldering iron tip to whatever is in contact with it. So everything lies in the ability of the person holding the soldering iron / solder sucker to combine good manual skill, expertise and knowledge ( you' ll find passive components like resistors and capacitors to be more a lot more forgiving than semiconductors ); my advice would be to get some old surplus card with ICs, diodes and transistors on it and use it as a guinea pig to improve your soldering/desoldering skills before doing something "for real".

Try removing the components from the old board and then measure them to see if you successfully pulled 'em out or you have ruined' em in the process.

Personally I use a 25/50W soldering iron and a manual solder sucker and they suit most of my ( and I would say everyone's ) needs in our field. To de-solder I usually put the tip on the solder as close as possible to the pin,
wait until the solder melts evenly and then with a single, fluid and rapid movement, I take away the soldering iron' s tip and I position the manual solder sucker perpendicularly, right on the pin and I press the release button.

Sorry, maybe I've been a little too wordy, anyway I hope this helps.

Best regards

Bob

[jrfrond]

That is a single-sided PCB, and removal of that IC is relatively simple with solder wick. The desoldering tool will probably cause you to overheat the PCB. It's great for hogging off lots of solder on big connections, but for fine work, it can be a bit frustrating. Learn to work with the solder wick.

The best solder for a novice (well, even for pros) is called "eutectic". This means it goes from molten to solid without the intermediate "plastic" phase, and it is much easier to obtain a nice, stable, shiny connection with. The alloy is 63/37 (as opposed to 60/40), but you will not find that locally at Radio Shack, so unless you want to order it online, 60/40 is your choice.

On another note, if your reverb drive chip keeps toasting, you might have a problem with your reverb pan. The problem with that reverb circuit is that those chips aren't good current drivers, which is why those pans have an 800 ohm input impedance as opposed to the 8 ohms on the tube-driven circuits. Makes for a cheaper circuit with a smaller sound, but if the pan develops a partial short on the input transducer, the chip will be worked really hard and could pay with it's life. I have seen these conditions on the bench before.

[olddawg]

I need to replace the IC Chip that drives the reverb on my Fender Hot Rod Deville. I would like to install a socket for future replacements. I have read the thread here that describes how to do this, it was helpful. I have an old but reliable weller soldering station that operates at plus or minus 750 degrees F. with the tips I have. So far I have not burned up anything "Yet".

I also have desoldering braid and have limited skills in solder removal with that. If I were to buy a desoldering tool from Radio Shack (45 watt) iron on it, is that too much heat or to eratic of heat to use on desoldering the cut IC pins from the circuit board? I have heard good and bad about solder suckers, so I am a little leary.

ALSO What is the very best reccomended solder for working with circuit boards and size?

Thanks in advance,

ENB

I used to regularly remove and replace 250+ pin ICs. IMHO the cleanest way to remove surface mount ICs is to use something like this: http://www.web-tronics.com/chipsmdsolre.html These kits are a bit pricey and you can find the stuff cheaper if you look around at electronics supply sites. We used to get the stuff in bulk.

Just make sure that you remove all the low temperature stuff and thoroughly clean the area with solvent when you are done. Use flux when you re-mount your socket or IC. If you encounter a double or triple sided board with pin through mounting you are better off with a good vacuum extractor. And yes, do practice on juck boards before you start messing with the genuine article.

[ENB]

That's the kind of information that helps.

Thanks to both of you for the quik reply. I do realize the duration/heat correlation on damaging PCBs and other components. A fellow ham operator and I used a signal tracer to locate a faulty filter cap which I have already ordered a complete set of Elettrolytics to have on hand. While in there, we checked values in the reverb circuit and found the TL*** IC to be noticable out of spec on on one of the outputs. I will recheck the reverb pan. Love this amp but am seriously considering ording a point to point amp kit from Torres to convert to an "All point to point".

As I live in "Backwoods USA" I have to order solder of decent qualit and am willing to pay a premium price for premium solder. I dont bash Radio Shack but find I have to order to get best quality tools and components. It seems as time goes on the "good stuff" is ever harder and harder to locate, even ording.

Thanks for both post which I will take under advisement for sure.

ENB

[Enzo]

I would describe it diffeerently as a procedure but agree it is not the power it is the technique. I hate using braid, but it works. STick the braid on the joint to be cleared and set the iron on top and press down. The solder sucks into the braid.

I use a professional Pace desoldering station, but when I need to do a quick job, I prefer the hand held sucker. I like the metal ones, but the plastic ones work too.



You push down the black plunger to cock it, then when ready, press the button and the pump springs back sucking in the solder.

Where I differ from Bob is this. Trying to pull the heat of the joint and placing the sucket over it to extract solder is iffy to me. The teflon tip of the sucket can handle the heat of the iron. Heat the joint, when the solder melts keep the iron on it and place the tip of the sucker right down on top if it. Now trigger it. The iron keeps the solder fluid, instead of racing with the almost instantaneous hardening of solder as the iron is removed. The old solder flows right around the iron into the sucker.

If I were you, unless I planned a lot of desoldering work, I wouldn;t bother with a dedicated desoldering iron, much as I love mine. Just use your regular iron and braid or a solder sucker tool.

SOme guys like the rubber bulb type, I hate them, I think they have the worst aspect of the various methods all rolled up into one item.



Do you plan to replace the reverb chips a lot? How many do you think are going to fail? I am not the largest fan of sockets in combo amps - vibration is a constant enemy.

SOlder? DOn't worry about it. Use rosin core electrical solder. The hardware store might have plain solder - no flux core. DOn't buy that. ANd plumbing solder has an acid core flux which will dissolve your circuit boards, so don;t buy that. Otherwise, we all may prefer one over another, but they are pretty much equivalent. For the hobbyist, I don't think anyone can make a serious case that the difference between 60/40 solder and 63/37 or whatever matters. I like Koester solder, but I just finished a roll of Ersin 5-core that I have had for years.

SOlder is sold by the pound, so you get a long piece of thin solder on the roll or you get a shorter piece of fat solder on the roll for your pound. Or ounce or gram or whatever. I like the thin stuff. Especially for work on circuit boards. When I need more solder I can always just run more in of the thin stuff. But if I need small amounts for connections with little space around them, it is hard to deliver a tiny dot of solder from the fat stuff. SO I prefer the .031 size.

[Enzo]

What do you mean out of spec? WHat specs do you even measure on a little op amp like that? Pretty much they work or they don;t in my experience.

[olddawg]

Enzo...Have you tried Chip Quick? It is a very low temp desordering alloy that looks like solder but isn't. You first wick up any solder then apply the Chip Quick. It will stay molten for 1 to 3 minutes while you can manipulate the IC and float it off. Afterwards you wick the Chip Quick off and clean the board with solvent. Since it is very low temperature and allows you a lot of time the board usually looks factory new after using it. I don't use it for everything but it deffinitely is a life saver in some applications.

[olddawg]

Anyone removing surface mount ICs should also be aware that they are frequently glued down with epoxy glue. This holds them in place in the wave soldering machine during mass production. If an IC is glued down, carefully cut of the legs around the chip body with an exacto knife, then unsolder and remove them. After that you normally have to carefully pop the naked chip off of the board with a screwdriver and a small hammer or similar tools.

[ENB]

What do you mean out of spec? WHat specs do you even measure on a little op amp like that? Pretty much they work or they don;t in my experience.

Enzo, thanks for the information. When I said "Out of Spec" Volatage was either non-existant or nearly non-existant either pins 5 or 6, It may have been all of the pins on the left side. Thanks for the advise on soldering. In the past few years I have had really good sucess in repairing numerous problems on various boards or performing mods on them with jumpers etc.

I have yet to totally master desoldering with braid, perhaps I never will.

With the reply's to my post, I am armed with a heck of lot more information than I had before I asked. This forum is a great tool.

ENB

[Enzo]

olddawg, I use chip quick, in fact I just used some to change an op amp on a Behringer mixer a half hour ago. But the ICs in this thread are plain old through hole DIPs.

ENB, look up "virtual ground" with regard to op amps. You often cannot measure signal right at the input pins of op amps.

Monitor the output on pin 7 and touch pins 5 or 6 with something like a meter probe. If you get some hum coming out, the IC amplified it and works. If in doubt, set the meter to ohms, the little test current it puts out won;t hurt the op amp, but will send a strong pop signal through it.