Cold solder joint problems ?

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cjacek

cjacek

Analogue Enthusiast
Can someone please tell me what the exact and typical symptoms of bad cold solder joints are, especially as it relates to recorders? Thanks. :)
 
yep... intermitents... do a visual check on all soldering useing a magnifier... i even try to flex the board too... if all else fails... try to narrow it down to a section and resolder everything... including desoldering... simply adding more solder can if your not careful add more bad joints to the board...
 
Yup, I thought it might be just that.

Here's the situation, to give you a better idea.... (Please bear with me). Channel 1 passes a distorted low level signal and when I work the RCA input by slightly twisting, flexing and moving the hooked up cable up, down and around, channel 1 has moments of good, strong signal. It may stay "fixed" like that for a good amount of time but then it returns to its former. Now, especially the manual manipulation doesn't work anymore but the signal / connection sometimes comes back after about 30 min or so of passing signal to it. There was an incident where I got channel 1 to work but channel 2 started pooping out. Then, when channel 2 worked, channel 1 died.

The one thing you need to be aware of is that when I put a signal tape on, all the meters play back fine, no problems. It's only when inputting signal. I also sprayed, initially, some deoxit into the RCA's and it seemed to have helped but that didn't last long. I doubt it's oxidation 'cause the deoxit should have fixed the problem but it didn't.

Does the above sound like classic cold solder joint probs ?

Thanks again guys! :)
 
Probably a cold solder, but it could also be a bad jack. Check the solder first.
 
Thanks again guys!

I do wish to update you however.. It seems RCA 1, 2 and 4 inputs are now problematic. What's more and THATS where I'm leaning toward it being the solder joints, is that the XLR inputs, also 1, 2 and 4 (above the RCA's), share the same problem. It must be the PCB, that both the RCA and XLR's share. Does that sound about right ? If it would be a bad jack, it wouldn't affect the XLR for that same channel, would it ? :confused:
 
yes I bought a really nice vintage sunn 4x10 bass cab for next to nothing a couple weeks ago because the inputs were "broken". More like intermittent. So I got in there with a desoldering braid, got the old joints removed, and re-soldiered (with the dangerous lead stuff) and good as new. while you're in there you might as well go ahead and clean everything too....get all the dust out, etc. Also make sure you haven't cracked the board the jacks are on....but that can be fixed too. you probably didn't break it, but wiggling things probably made the joints worse.
 
Is it usually a good idea to do ALL of the solder joints as a preventative measure, even for the connections that don't need it ?
 
I would perhaps reheat all of the inputs and outputs since they have probably seen similar wear.
 
So basically redo all the solders for the input / output ? Just on the PCB board or also at the jacks ? Thanks Falken.
 
It seems that way, yes but then again, this is coming from someone who is not electrically inclined, so I'm not sure. The RCA's seem to be attached to the PCB directly, as in no wires.
 
so i guess then the two sets of solder points you ask of are one in the same......
 
It's pretty common for jacks to work themselves loose on older equipment, and/or oxidation to buildup on the jacks.

But I have to ask... have you tried different cables? It also wouldn't be unusual for older cables of the same type to start failing at the same time. This can happen with a snake or individual cables that have common vulnerabilities to physical stress and environmental conditions.

For example I’ve had cables from the same pack start to crackle and cut in and out after a few years because the copper was turning green or the molded connecters where poorly done. You would have to test with a different brand of cable to eliminate that as an issue.

:)
 
Thanks Tim but I tried different cables and also used new ones and even checked against other, known to be good, gear. There's def something breaking the connections, either some deeper oxidation issues or solder joint fractures. Interestingly, when I left it overnight, switched off of course, the next day all the channels were ok except the 1st one. Sometimes for whatever reason, that one works too, without me doing anything, it comes back on its own .... and the .... boom .... doesn't work anymore. Even sprayed some more deoxit into the RCA jacks but that doesn't seem to help at all. Whatever it is, I'll have to dig a bit deeper but the term "intermittent" sure fits here perfectly.
 
not to beat the dead horse but i cant stress enough that to simply"heat" the connections or add a bit of solder OFTEN causes more problems... ya gotta get in the habit of desoldering first.... WAY important....
 
cjacek said:
Thanks Tim but I tried different cables and also used new ones and even checked against other, known to be good, gear. There's def something breaking the connections, either some deeper oxidation issues or solder joint fractures. Interestingly, when I left it overnight, switched off of course, the next day all the channels were ok except the 1st one. Sometimes for whatever reason, that one works too, without me doing anything, it comes back on its own .... and the .... boom .... doesn't work anymore. Even sprayed some more deoxit into the RCA jacks but that doesn't seem to help at all. Whatever it is, I'll have to dig a bit deeper but the term "intermittent" sure fits here perfectly.
Click to expand...

OK. If I were fixing this problem the first thing I would do is bypass the connector completely. Take a crappy cable and unsolder the connector. Now, solder the wires to the board after the connector (right where the connector is soldered to the board). If you have any problems then, it would be a bad solder connection to an op-amp, fractured etch, fractured through-hole, power supply problem and a couple of hundred other things but NOT a connector problem.

Hope this helps.
 
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