Jedi battery contact removal

[kf4sqb]

I'm trying to replace the battery contacts in an HT1000. I have a couple of old Visar boards sent to me by another board member for parts, and I'm trying to remove the pins from them first. Since they're already dead, they make good guinea pigs to experiment on . The positive pin was no problem to remove. A couple of seconds with a 25 watt iron, and it came right out. The negative, however, is a different story. I've held heat on it for over a minute with both a 25 watt and a 45 watt iron (yes, both at the same time), and it didn't show any sign of turning loose. Do I need to break out the 120 watt gun? The Visar boards are disposable, but I'd rather not destroy the HT1000 board, as its not mine. Suggestions?

[fineshot1]

I have the same issue for some GE Panther portables. I think there must be a special soldering iron tip that fits over and surrounds the pins distributing the heat evenly and allows the solder to flow. Thats just my best guess as it seems some of these pins just wont come out short of destroying the board.

[spectragod]

Pre-heating the board is your friend.

SG

[fineshot1]

Pre-heating the board is your friend.

SG

How does one go about doing that without causing other complications? We are a simple service shop and do not have much in the way of SMT tools although I can do simple repairs. Are you refering to a special type of heat gun?

PS - I like your location

[spectragod]

I used the board preheater that came with our chipmaster, and then put the soldering iron to it, I found they ae almost impossible to remove otherwise.

SG

Pre-heating the board is your friend.

SG

How does one go about doing that without causing other complications? We are a simple service shop and do not have much in the way of SMT tools although I can do simple repairs. Are you refering to a special type of heat gun?

PS - I like your location

[kf4sqb]

Spectragod, that sounds good, but I don't have access to such equipment. I'm just a hobbyist. Should I maybe put it in the oven at 350 degrees for 15 minutes? Do you think that would damage anything on the board?

[spectragod]

I don't think I would recommend that, as you may have SMC's falling off the board, just FYI.

SG

Spectragod, that sounds good, but I don't have access to such equipment. I'm just a hobbyist. Should I maybe put it in the oven at 350 degrees for 15 minutes? Do you think that would damage anything on the board?

[kf4sqb]

I don't think I would recommend that, as you may have SMC's falling off the board, just FYI.

SG

Spectragod, that sounds good, but I don't have access to such equipment. I'm just a hobbyist. Should I maybe put it in the oven at 350 degrees for 15 minutes? Do you think that would damage anything on the board?

250? Seriously, how hot do you think I can get it? I've got two old Visar boards as parts donors. I may get brave and try it with one of them to see what happens.

[WB6DGN]

"

Should I maybe put it in the oven at 350 degrees for 15 minutes?

I don't know about battery contacts, but that sounds just about right for reheating pizza.

Seriously, though, you want the bottom heat on while you're applying heat to the top to remove the parts. I think, by the time you take it out of the oven and over to the bench it would have cooled down so as not to do any good. I also always used a Chipmaster to remove and install the contacts but one of the guys I worked with refused to use the hot air and always did it with his soldering iron (I think his iron was about 60 watts) so I know it can be done. Unfortunately, I can no longer get in touch with him to find out how he did it. If you have access to a hair dryer you might try blowing that on the bottom of the board using as much heat as you can get out of it while you try to unsolder the contacts from the top If that works, use the same procedure to install them in the new board. I wouldn't try a heat gun, especially on the good board as they get way too hot even on the 'low' setting. You'd probably lose a bunch of parts in the process, not to mention probably delaminating the good board. Good luck,
Tom

[kf4sqb]

I think, by the time you take it out of the oven and over to the bench it would have cooled down so as not to do any good.

Why would I want to take it back to the bench to work on it? I'll do it right there on top of the stove. I'm sure my wife would raise the roof, but she'll get over it (eventually )....

Seriously, though, you might have an idea with the hair dryer. I may just try that and see how it goes. At least I have a pair of donor boards to try it out on. If I ruin one of them, I know not to try that method on the good one! I'll let everyone know what method I use, and how well it works. Thanks for the ideas!


BTW, how hot is the air coming out of a "real" SMD station? Correct me if I'm wrong here, but isn't there a blower that blows air hot enough to almost melt the solder across the entire board or area of a board to pre-heat it, then a "pencil" that blows air just a little hotter in a very small stream to do the actual component-level work? I may just try to build a home-brew station one day...

[WB6DGN]

BTW, how hot is the air coming out of a "real" SMD station?

It's adjustable and it varies, but I usually used between 375 and 425 degrees end heat for most jobs. It depends a lot on how much ground plane is in the area where you want to work, the number of layers the board has, the size (mass) of the item you want to remove or install, and so on. Also, the heat doesn't usually go right up to maximum but will increase gradually, holding at one or more intermediate points for a while, again depending on the characteristics of the item you're working on. The manufacturer of the machine usually specifies these "profiles" for common items and will work with you to develop one for an uncommon or new item. Obviously, from the temperatures above, eutectic solder is used and I don't know what changes will come about with ROHS procedures but I'm glad I retired before that became common.

By the way, don't forget when you work on the stove to leave a few spots of rosin and a little solder behind; it's always good for a laugh. Hi.

Hope this answers your question

Tom

[kf4sqb]

Hope this answers your question

Part of it. Did I get the general design right, as far as the "preheat area" and "pencil"?

[kf4sqb]

I have a contact removed from one of the "donor" boards. I did wind up using the oven. I started with a cold oven, put the board on the top rack on a piece of aluminum foil (just in case nasty things melted/got gooey/fell off), and put an oven thermometer on the rack beside it. I started timing, just to keep track, when the flame ignited. I initially set the oven to 200° F, and let it go, keeping a frequent visual check on the board, until it actually reached 200° by the thermometer. That took about 10 minutes. I then took it out, and tried to melt the solder with a soldering iron. No joy. Back in the oven, turn it up to 250°, and wait another five minutes until the oven reached 250°. Took it out, and tried again. Still no joy, but the solder will actually melt all the way around the pin on the side the iron was on (back). Back in the oven, now set for 300°, for another five minutes. Took the board back out, applied the iron for a few seconds, and slid the pin right out! Final temp was 285° according to the thermometer. I see nothing melted, distorted, deformed, soft, or moved. I saw no smoke, and smelled no strange odors during the heating procedure. No signs of board warpage or de-lamination, while hot or after it cooled (air-cooled, at it's "own rate").

So what does everyone think? I personally think everything's OK. Any ideas, comments, speculations, or advice at this point?

BTW, I also tried using an 1875 watt hair dryer, with a nozzle on the end that forms the air stream into a "flat fan". The board was put directly in front of the nozzle (slightly inside the end of it, actually), and left for 15 minutes. It didn't even get too hot to hold bare-handed. I tried turning the hair dryer on the oven thermometer to get an idea of how hot it was getting, and it only showed around 130°.

[kf4sqb]

I'm reviving this thread to post my final results. I removed the pins from both "parts donor" boards using a regular residential gas oven, set to 300 degrees F. I noticed no visual damage to either board or any of the components on them, so I got brave and tried the good board. I put it in a cold oven, and turned the oven to 300 degrees, then waited for it to reach temp, while checking the temp with an oven thermometer. Took it out of the oven, applied a soldering iron to the pins, and slid them right out. Due to time restraints, it was a few days before I managed to try putting the pins back in it. I followed the same procedure as for removal, with the exception of "seating" the pins with a little solder, then putting the board back in the still-hot oven for around 6-7 minutes, then took it back out and added a little more solder to the base of the pins. Put the radio back together, attached a battery, and powered it up. Success! The radio works fine, although I haven't actually checked it out on a service monitor or anything, as I don't have one. Thats one problem I hope to be able to remedy in the next few months, though. Hope my little experiment help someone out!

[wavetar]

A simple Weller heat gun held in position for 20-30 seconds is perfect for heating the board in specific locations to allow you to remove parts like this easily with a soldering iron afterwards, as well as Maxtrac power connectors, GP300 style accessory connectors, power amplifiers...anything requiring a lot of heat basically. Old tech trick, far easier & quicker than an oven!

Todd

[kf4sqb]

That may well be, but I don't have a heat gun, nor do I have enough need for one to justify buying one. I'm just doing the best I can with what I have available. What can I say, I'm used to having to make do.

[wavetar]

Not slamming your method, simply pointing out a long time accepted tech trick which works well. FWIW, you can probably pick up a heat gun at surplus stores for $20.

Todd

[kf4sqb]

I well understood your point Todd. I didn't think you were "slamming my method". I was simply illustrating my reason for using the method I used, as well as passing it on on the chance it may help someone else. I don't do that much of this type of work. I'm not running a shop here, I'm just a hobbyist (and Motoholic ).