PCB damage repair
- Thread starter Nen'O
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Ricardus
WILL SOLDER FOR FOOD
Which part of the PCB are you talking about?
Why not give it a good 99% alcohol cleaning first and upload another pic?
Why not give it a good 99% alcohol cleaning first and upload another pic?
Екатерина
Active member
Can the solder pad come off? It can be connected to the disconnected circuit with enameled wire, and repairing it is very troublesome
I'm curious to know how that happened.
I used cheap desoldering pump which I believe overheated or pcb wasn’t of the best quality. Anyhow mic worked and now doesn’t work even if I put old capacitor :/
MidnightArrakis
Well-known member
Try using some -- solder-braid -- or a "solder-sucker" to clean-up and get rid of all of the excess solder around all of the component pads. Then, as > Ricardus < has suggested, thoroughly clean the PCB with a good "board-cleaner" solution and get the PCB back into being solderable and workable once again!!!
From there.....I would then also suggest to replace all of those black electrolytic capacitors with new ones, as they all look to me to be rather pitiful at best!!! In addition, make sure that you have the electrolytic capacitors inserted in the correct way, as a -- backwards -- inserted electrolytic capacitor certainly won't do you any good whatsoever!!!
Should a component solder-pad or two have become lifted off of the PCB, the best that you can do is to then very carefully scrape-off some of the soldermask off by using an -- EXACTO -- knife in order to expose a small portion of the remaining circuit-track and then solder the correct capacitor lead to it.....carefully!!! Not too much heat, now.....OK???
And, finally.....just remember.....while "cheap" may save you some immediate money whenever you buy an item that you need or want.........."cheap" will always end up costing you > MORE < in the long run, due to the unknown and unforeseen problems that that item will eventually cause you in the end!!! Just sayin'.....
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Tips on removing things:
If removing a header, use a vice to hold the board vertically, then heat each pin, while pulling it from the other side with needle nose, but wait until it's hot and then grab quickly. Then clean the holes with a SOLDAPULLT, which is the best one made.
When removing a resistor or cap (assuming you don't want to keep it) cut the part flush with the board and suck the lead out from the rear side. Less heat sinking, and clean results.
When using a heated vacuum solder sucker, never press hard on the pad, slip it over the lead, let it sink, then lift it up a hair, then move it around, while pressing the button.
When using wick, make sire it's the kind with flux built in. If not, buy "no clean liquid flux" and squirt some in the plastic holder. Again, don't press down hard.
When soldering in chips with close SMD pads, just flow the solder on all the pins at once, then use the wick to clean up the mess. Makes a perfect solder job.
https://www.amazon.com/EDSYN-The-Original-Deluxe-SOLDAPULLT/dp/B006GOKVKI?th=1
If removing a header, use a vice to hold the board vertically, then heat each pin, while pulling it from the other side with needle nose, but wait until it's hot and then grab quickly. Then clean the holes with a SOLDAPULLT, which is the best one made.
When removing a resistor or cap (assuming you don't want to keep it) cut the part flush with the board and suck the lead out from the rear side. Less heat sinking, and clean results.
When using a heated vacuum solder sucker, never press hard on the pad, slip it over the lead, let it sink, then lift it up a hair, then move it around, while pressing the button.
When using wick, make sire it's the kind with flux built in. If not, buy "no clean liquid flux" and squirt some in the plastic holder. Again, don't press down hard.
When soldering in chips with close SMD pads, just flow the solder on all the pins at once, then use the wick to clean up the mess. Makes a perfect solder job.
https://www.amazon.com/EDSYN-The-Original-Deluxe-SOLDAPULLT/dp/B006GOKVKI?th=1
I don't much like the idea of soldering a capacitor onto an exposed trace -- especially not in gear that is going to be moved around. But it will work.
Instead, I'd solder a wire onto that trace, apply some UV-curing PCB masking ink, and for holding the capacitor lead form an unmasked loop. Gives better stability.
Instead, I'd solder a wire onto that trace, apply some UV-curing PCB masking ink, and for holding the capacitor lead form an unmasked loop. Gives better stability.
I get those from Banzai in Berlin. Probably a Chinese copy, but they work like a charm for years. And at a fraction of the cost.
https://www.banzaimusic.com/Desoldering-Pump-PRO-601.html
https://www.banzaimusic.com/Desoldering-Pump-PRO-601.html
The older style metal solder suckers I avoid using on older style pcb's ,
the recoil and mechanical shock can easily damage traces ,
A lighter plastic sucker probably isnt so bad ,but where delicacy is needed solder wick is your best bet.
I also suggest a soldering iron with temp control or your only going to do damage to finer traces .
the recoil and mechanical shock can easily damage traces ,
A lighter plastic sucker probably isnt so bad ,but where delicacy is needed solder wick is your best bet.
I also suggest a soldering iron with temp control or your only going to do damage to finer traces .
First up there is no evidence you have “melted” the PCB board - PCB boards don’t melt, they surface burn and the traces can lift off - the excess shiny effluent in your pic looks like it’s just solder flux - this will clean off with isopropyl alcohol - use a fine stiff artists paintbrush dipped in alcohol to soften the flux and another dry one to brush away the excess being careful not to flood the board. Then take a new pic and upload it - can’t see if you’ve damaged any traces with all the reflections off all of the pools of excess flux.
Second there appear to be a few vacant holes in the board just above the letters FL00560 - and also just above the lower electrolytic. What was in those holes and have they been replaced after this photo was taken? There’s evidence they were recently desoldered.
Thirdly - are the two electrolytic capacitors shown in the correct way around? Did you take before and after photos?
Whenever I commence any job I full photograph the whole area including all cable terminations so if a wire breaks off I know where it came from.
If replacing polarised capacitors I take location/polarity identification shots. Looks like those caps are 400V - is this a tube mic? Also were they originally on the other side of the board? Why are you surface soldering them to the board instead of going through-hole?
Second there appear to be a few vacant holes in the board just above the letters FL00560 - and also just above the lower electrolytic. What was in those holes and have they been replaced after this photo was taken? There’s evidence they were recently desoldered.
Thirdly - are the two electrolytic capacitors shown in the correct way around? Did you take before and after photos?
Whenever I commence any job I full photograph the whole area including all cable terminations so if a wire breaks off I know where it came from.
If replacing polarised capacitors I take location/polarity identification shots. Looks like those caps are 400V - is this a tube mic? Also were they originally on the other side of the board? Why are you surface soldering them to the board instead of going through-hole?
If using the manual sucker (and not my air pump de-solder gun) I burn a tiny “U” into the side of the sucker tip so it nests perfectly over the iron tip and gives max suction while the solder is melted. Works like a charm!
Solder wick is great - quick and even gets the solder out of feed through holes - you just need to be careful about applying too much heat and putting pressure against fragile solder pads. I usually pre-tin the joints I am going to de-solder so there is fresh flux and the solder flows easily.
Hey thanks for advices.
Yes it’s tube mic mod.
Im modding a pair of SCT 2000 with stock pcb into U47 inspired mic with UTM 0547 transformer, K47 capsule from Maiku and EH 12Y7 tube.
Capsule, transformer and tube mod went great. I was waiting for caps order to arrive so it was the last mod.
Since it’s standard apex 460 style mod I removed C9, C10 , C6, C7, to fit new C8 I had to move on the back(tube) side C1 and C2.
First mic mod went great and I’m very happy with result, the second mic mod got complicated.
Here is a photo of modded working mic.
I’ll give a try to fix other mic with advice you shared.
Thanks
Yes it’s tube mic mod.
Im modding a pair of SCT 2000 with stock pcb into U47 inspired mic with UTM 0547 transformer, K47 capsule from Maiku and EH 12Y7 tube.
Capsule, transformer and tube mod went great. I was waiting for caps order to arrive so it was the last mod.
Since it’s standard apex 460 style mod I removed C9, C10 , C6, C7, to fit new C8 I had to move on the back(tube) side C1 and C2.
First mic mod went great and I’m very happy with result, the second mic mod got complicated.
Here is a photo of modded working mic.
I’ll give a try to fix other mic with advice you shared.
Thanks
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Sounds like you’ve either broken a print track or one of the wires has become disconnected - just use the working mic to backtrace what was done on the second. Make sure you’re getting filament heat and B+ as well.
This is a closeup snip of the lower capacitor in the first picture posted.
The lower leg is not soldered at all, and the upper leg is not soldered properly (the solder is present, but it did not flow up the leg of the component, indicating that the joint was not heated to the proper temperature).
The lower leg is not soldered at all, and the upper leg is not soldered properly (the solder is present, but it did not flow up the leg of the component, indicating that the joint was not heated to the proper temperature).
Hi, thanks for pointing out.
Mouser order was for some reason divided into 2 packages, I’m still waiting for new electrolytic capacitors. Those old caps will go out anyways and It will be much easier to instal new caps without extending wires. Other thing I noticed C8 on new sct2000 has soldering points on two places on pcb. Like they already had in mind to install large capacitor in there. That will make job much easier.
