Fixing old guitar amp input jack -made a mess. - Page 1
Forum section: electronics / beginners

author: lukemoire
author_rank: Newbie
timestamp: October 19, 2024, 09:59:40 am
content: So, I got back with my old band -sorry, just some context- and got myself and old used amp.I soon found out that the guitar jack had to be angled/pushed in certain way when it was plugged, otherwise no sound. It was clear something wasn'tconnecting.Saw this video -pasting the relevant bit- where the same amp had an even worse problem (no sound at all).https://youtu.be/JerZn4d_PLI?si=mozBxd7j1dI2FomE&t=191Just as he does I went over a few of the connection-joints, please see my image 01. Although I didn´t use any wiring as he does.Q1: Do those look fixed to you?After that I made a foolish move -total idiot, not knowing what I'm doing- I decided to drop more tin in some random place, please see my image 02Q2: how to fix this? Shall I melt it first? I assume I need the two right connectors or pins -lack vocabulary, sorry- separated, as the two left ones.Current state: I plug my guitar and nothing happens. Amp turs on fine.Thanks in advance to anyone who stops by.Luke

author: BILLPOD
author_rank: Frequent Contributor
timestamp: October 19, 2024, 01:15:05 pm
content: Good Morning Lukemoire, you have inadvertently created what is called a 'Solder Bridge'.You can remove the extra solder with some solder braid. Not a difficult fix. Lots of solder braid on Amazon.

author: tooki
author_rank: Super Contributor
timestamp: October 19, 2024, 02:05:04 pm
content: Quote from: lukemoire on October 19, 2024, 09:59:40 amLet me guess, you melted solder onto the soldering iron tip and then tried carrying it to the board, right?That won’t work. I would highly recommend the following video series to you:https://www.youtube.com/playlist?list=PL926EC0F1F93C1837(English)https://www.youtube.com/playlist?list=PLZ4bp4FXracJT7RjZ-WOIQsVG303V9aM2(Spanish)Despite their age, those videos are the clearest, best explanation of the soldering process I have ever seen. It is well worth the time, and I recommend them to anyone who lifts a soldering iron even once. (Under an hour in total for all 9 lessons, so I recommend watching them all, but if you’re in a hurry, lesson 1 is by far the most important, and 6-8 are relevant for you.)After that, watch this video specifically on repair:(English)(Spanish)As for your numbered questions:Q1: No, they don’t look fixed. You’ve applied huge blobs to the tips of the leads, but it doesn’t look like it flowed to the pads. Remove the solder with wick and resolder properly.Q2: Remove the solder with wick and resolder properly.

author: Ian.M
author_rank: Super Contributor
timestamp: October 19, 2024, 02:12:03 pm
content: More correctly called 'desoldering braid', also known as 'solderwick'. *GOOD* western brands of desoldering braid (e.g. Chemtronics or MG Chemicals) work well without extra flux, but most of the cheap desolder braid needs extra flux to pick up solder well. When buying flux, it *MUST* be electronics grade, with absolutely no acid chlorides (e.g zinc chloride or ammonium chloride). Flux with acid chlorides is only suitable for plumbing as it rots thin copper e.g. PCB tracks and stranded wires!I agree with Bill that the solder bridge is best removed as he described, but would go further:I believe the joints you have reworked are probably still bad. Excess solder is *not* good as it conceals whether or not the solder is making a good connection to the pad underneath. A good solder joint between a pad and a through-hole component lead is a cone a bit like a volcano with smooth, slightly concave sides.Also mixing solder alloys can cause severe problems - as little as 1% Lead (Pb) can make a lead-free solder joint brittle and liable to cracking. Depending on the age of the equipment, it may or may not have lead-free solder. Pre RoHS equipment should generally be required with Sn60/Pb40 or SN63/Pb37 solder and post RoHS equipment with a compatible lead-free solder to avoid this embrittlement issue. SAC405 is one of the better lead-free alloys for manual rework, and would be my first choice for repairing newer equipment. It is generally advisable to remove as much of the old solder as possible using desoldering braid, then remake the joint using new solder, which also minimises the risk if you have misidentified the RoHS status of the board.Tooki's advice to watch the PACE training videos is excellent.When you have reworked all the suspect pads, use a multimeter with a continuity test beep to test continuity from each joint to the next one on the same track. This will detect if there are cracks where the tracks meet the pads.If you find any bad connections due to cracks between pads and their tracks, you should desolder the offending joint, scrape back the solder mask on the adjacent track and re-make it with a short bare wire embedded in the joint, extending the joint from the pad to the track to bridge the break. If you are in a hurry to test if the break is the only problem you could instead add an insulated wire link to the next joint as in the repair video you linked in your initial post, but this is generally regarded as a 'bodge job'

author: Old Printer
author_rank: Frequent Contributor
timestamp: October 19, 2024, 02:13:32 pm
content: If you are going to gig with this amp you should try to find someone who knows soldering. A bridge is easy to fix, but your other joints look like they may be "cold". That is not enough heat during the process, though a dirty joint can look that way too. The finished joint should be shiny. Soldering is pretty easy to learn, but you should practice on something that is not going to have you on stage with an audience. If this is a tube/valve amp that has sat a while you should also get it serviced. Tube sockets can oxidize and make intermittent contact, which usually fails at the worst moment. Depending on age, capacitors, particularly electrolytic ones, are also a weak link that should be checked, along with ground connections. All of these things can be DIY and the info is all over Youtube, including proper soldering. Rock on

author: themadhippy
author_rank: Super Contributor
timestamp: October 19, 2024, 02:52:23 pm
content: personaly,if possible,id junk the circuit board, get new panel mount jack sockets and take the wire directly to the sockets.Those socket take a lot of abuse and a common failure is the socket coming away from the pcb.

author: RJSV
author_rank: Super Contributor
timestamp: October 19, 2024, 05:10:08 pm
content: Luke, hello:Looking at your first photo, that solder isn't that bad or hard to fix. Buy a 'braid' which comes with solder irons. To pull off extra solder, you lay the braid end down onto the joint, and then push the (hot) iron tip into the braid surface, with a bit of pressure.Wait for a few seconds, and that wire braid will pull the solder up, into itself. That means that you've transferred the solder, while it's melted. Might be a good idea to clean that area at that point.For the braid, simply clip off the little end that has solder in it now...discard.You need to then scrutinize the traces...not that hard. You can observe how the traces don't touch, so logically any 'solder bridge' will be a problem.Might be time to start learning some basics. Can you buy a multimeter ?Using ohms scale, you can at least check for shorted traces. But keep in mind, that if that jack has a switch contact, the two lines from the switch will appear as 'shorted' or connected. In fact, if you are curious, could try inserting a plug in the jack, as that should push any switch to an open position.I don't know, but that plug inserted SHOULD cause (any) switch to show as 'infinite' or open circuit, a correct result.It's troubling that a wiggle, of the inserted plug, would cause flakey contact...that might indicate Jack is bad / worn. If you can figure out the two contacts needed, you could, optionally, arrange to mount a fresh new JACK, put that in a secure mount, or make a secure mounting nearby, for your use.That is ground, and signal that you would be using, to create an alternate. You might be able to test your new mounted jack, temporarily, and then solder the wires better.

author: floobydust
author_rank: Super Contributor
timestamp: October 19, 2024, 05:52:55 pm
content: OP, you can simply melt the solder on the bridge, then quickly tap the pc board on your desk and the excess solder will fling off. If you are in a bind.Also note the fractured solder joint in your pic, it's still not fixed. In the top right see the crack.

author: lukemoire
author_rank: Newbie
timestamp: October 19, 2024, 07:46:41 pm
content: Hi everyone,Thank you all for your replies. Indeed, this was my first time soldering anything at all.It will take me some days or weeks to get to this, but I will share the result.These tips, links, and comments are pure gold and the energy here is a true mine.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: October 19, 2024, 08:59:04 pm
content: Get some flux paste and a hot iron. You can clean that up fairly easily. Use a big bevel tip something similar.https://www.amazon.com/Solder-Soldering-Rosin-Lead-Free-Electronics/dp/B08MVXW4RY

author: RJSV
author_rank: Super Contributor
timestamp: October 19, 2024, 11:15:34 pm
content: Oh, and I should also mention one method for cleaning flux;With a piece of tissue, and a stiff (plastic) brush, plus some SAFELY STORED alcohol,you place the coarse tissue down on the area to be cleaned. The little brush is dipped in a small amount of alcohol and used to 'stipple', which is a series of downward plunges or 'stabs', and some sideways scrubbing movements.Might not seem right, but the dirty flux, being in the other side, from the brush, will be absorbed, even though the brush ends don't really contact, directly.So, you do the stabbing motions and note that some flux will be transferred up and absorbed from underneath (the coarse paper).Oh, and try to avoid contaminating your alcohol, by wiping the brush, before going back to dip, a few times.Regular soldering 'stations' in factory floors, etc. will have that alcohol in a little bottle with a special top: Pushing down on the bottle top, with your brush, causes a few drops to be dispensed, to your plastic brush.Probably go back and forth maybe 4 times, to clean a small area...30 seconds and done.Don't forget; That tissue is a hazard, so dispose of the flammable thing properly.

author: CaptDon
author_rank: Super Contributor
timestamp: October 20, 2024, 01:55:45 am
content: If the original jacks were the plastic crap which means the ground part was isolated from the metal chassis front panel you may find that using an all metal replacement (which I do prefer) could cause ground loop noise or some A.C. hum based on how the main circuit board is designed. You may have to insulate / electrically isolate the shell of the jack from the metal chassis with fiber washers.

author: RJSV
author_rank: Super Contributor
timestamp: October 21, 2024, 04:40:05 pm
content: I don't want to give bad or outdated info; but I recall might be ACETONE that is used, for cleaning flux, while doing repairs at the factory.Either way you must remember about proper handling, to be safe from any fire.In the diagram, I've shown the bottle of solvant, with the brush used to clean flux. The bottle lid will release a drop of fluid, when pressed down, by the brush tip.Oh and also some folks prefer using a solder sucker tool, rather than the brush and tissue I've shown.

author: RJSV
author_rank: Super Contributor
timestamp: October 21, 2024, 04:41:34 pm
content: Here is picture of solvent dispenser.