Author Topic: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.  (Read 2259 times)

movinginslomo

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Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« on: January 18, 2021, 12:34:48 PM »
 >:( >:( >:( >:( >:( Trying to replace the pots on an old midiverb II rackmount. Finally found replacement pots. Waited on backorder. Show shipping via USPS and their problems. Tried to remove old pots, barely got them removed, lot a pad, gave up. Ordered non working midiverb (pots and pot daughter board seem ok) going to try to assemble a working unit. How do these old computer restorers on youtube do it? Trying to remove through parts on a 20+ year old wave soldered board is damn near impossible. it's like you need a small iron on both ends of the board. And that's with copious flux. And fresh solder. Should I never be attempted to do something this aggravating in the future, any tips?

jimilee

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #1 on: January 18, 2021, 02:19:29 PM »
You can just run a jumper to the next component if you lose a pad. And  I don’t k ow, lots a patience and solder sucker tools.


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davent

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #2 on: January 18, 2021, 02:27:59 PM »
Cut the parts free first then only have to deal with desoldering/removing a tiny stub of lead from the hole?
dave
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movinginslomo

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #3 on: January 19, 2021, 09:47:13 AM »
Oh I tried every trick in the book. The three pots are board mounted, double gangs with two rows of three pins. They sit flush to the board, with enough gap that solder wicked through the hold and welded them in place. I had to dissect the pots, drill out the rivets, basically rip them apart, then try to remove the pins. Still managed to lift a trace and pad. Then attempted to clean out the holes with solder wick (I need new wick, this wick I have DOES NOT wick solder, even with copious flux). The holes managed to stay partially stubbornly plugged, blocking the holes from the new pins. After a couple more pad lifting issues (the pads were in bad shape after removing the original pots) I basically cut my loses. There are always units on reverb and ebay for repair and snagged another cheap with a board issue. I'm gonna try and harvest the front panel/pot daughter board assembly. Mine has a bad segment in one of the 8 segment displays anyways. Come to think of it, I see a lot of retro computer guys doing this, maybe I should have taken this route in the first place!

Which begs the question, when you have a part mounted with solder on both pads, how can you remove it? You can only wick/suck up so much solder, and one side will always stay solid.

lars

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #4 on: January 20, 2021, 03:51:32 PM »
...lots a patience and solder sucker tools.
You may want to pick up something like this: https://www.amazon.com/YIHUA-Desoldering-Variable-Temperature-Function/dp/B08BK69H2M/ref=sr_1_5?dchild=1&keywords=vacuum+desoldering+station&qid=1611178655&sr=8-5"

I've been wanting one of these desoldering stations. It's the only logical way to remove solder. The solder needs to be being melted AND sucked at the same time. Desoldering pumps try to suck up the solder after you've removed the heat (doesn't work well). Wicking braid is just plain garbage. A heated solder vacuum...that's the ticket.
News...

peAk

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #5 on: January 20, 2021, 04:20:34 PM »
I'm not a fan of solder suckers or braid

I finally said screw it a couple of years ago and bought one of these. I have never regretted it.

https://www.amazon.com/dp/B07BFVFMS9/ref=cm_sw_r_cp_apa_fabc_yVkcGbH0TNX98


 

davent

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #6 on: January 20, 2021, 04:41:36 PM »
...lots a patience and solder sucker tools.
You may want to pick up something like this: https://www.amazon.com/YIHUA-Desoldering-Variable-Temperature-Function/dp/B08BK69H2M/ref=sr_1_5?dchild=1&keywords=vacuum+desoldering+station&qid=1611178655&sr=8-5"

I've been wanting one of these desoldering stations. It's the only logical way to remove solder. The solder needs to be being melted AND sucked at the same time. Desoldering pumps try to suck up the solder after you've removed the heat (doesn't work well). Wicking braid is just plain garbage. A heated solder vacuum...that's the ticket.

If you have the right solder sucker you don't remove the soldering iron while drawing the molten solder off with the pump.

De-soldering braid, some works well some doesn't, probably more to do with my technique than the braid.
dave
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thesmokingman

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #7 on: January 20, 2021, 05:00:54 PM »
fwiw I always start every desolder by adding fresh lead solder and flux ... I'll even add more during the process if I find things quit moving

I use the little bulb solder sucker for blowing solder out a hole, I use the spring loaded sucker for pulling solder up, and I use flux soaked braid for cleaning pads or lifting excess solder up.

I am a big believer in using a vise or helping hands so I get both hands free and gravity on my side.

I also subscribe to destroying a part vs destroying a board (short of something I simply can't replace)

once upon a time I was Tornado Alley FX

movinginslomo

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #8 on: January 20, 2021, 10:29:15 PM »
If I was going to do more gear restoration on a pro-level yes I'd buy one of those fancy pumps, probably the best tool for the job.
I do have ones of these:



But it's not all that great, and I probably need to clean it out. Back in the day before Alesis was sold off, you could send the units back for repair, and I'm sure they used that kind of stuff. Sucks now all this old gear is in the hands of us novice hobbyists to try and salvage. Speaking of which the summer before last my dad spent rehabbing an old Commodore 64 and an Amiga 500. Both of which proved daunting. The other wild thing was he had got the c-64 software collection of a local video game reviewer from back in the day and CLEANED THE FUCK UPPP on some of the in box titles, some with original shrink wrap. He didn't believe me when I said the retro tech collecting community is insane! I think one one title alone he got $250!

zgrav

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #9 on: January 25, 2021, 03:52:37 PM »
one quick tip to share I learned recently -- best way to open a through hole on a board is heating the solder and then putting a toothpick into the hole and let it cool.

davent

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #10 on: January 25, 2021, 04:12:04 PM »
one quick tip to share I learned recently -- best way to open a through hole on a board is heating the solder and then putting a toothpick into the hole and let it cool.

A stainless steel dental pick is good for this as well and a myriad of other uses as well.
dave
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If my photos are missing again... they're hosted by photobucket... and as of 06/2017 being held hostage... to be continued?

matmosphere

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #11 on: January 25, 2021, 04:17:56 PM »
one quick tip to share I learned recently -- best way to open a through hole on a board is heating the solder and then putting a toothpick into the hole and let it cool.

That is brilliant. I think this tip alone could have saved me countless hours of troubleshooting issues.

jimilee

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #12 on: January 25, 2021, 04:28:25 PM »
one quick tip to share I learned recently -- best way to open a through hole on a board is heating the solder and then putting a toothpick into the hole and let it cool.

That is brilliant. I think this tip alone could have saved me countless hours of troubleshooting issues.
Ahhh nice. I’d be using an earring with a post, but I be this wouldn’t wreak havoc on a PCB.


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movinginslomo

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Re: Old through-hole PCB repairs. AAAAAAAAAAAUUUGHHH.
« Reply #13 on: February 07, 2021, 09:58:22 AM »
Tried toothpick trick.. worked a little.. still better solder wick.

Now onto the rest of the tale as it gets.. crappy. Order a non working unit from a guy in NC, two weeks, no item, no tracking, not answering messages. Get reverb involved. Get a refund denial. "claims shipped". get reverb involved again. Only then do I finally hear from the seller. He never had the item, he already sold it. But took my money anyway. Reverb refunded me. WTF. If you don't have an item remove the listing and don't steal people's money.

Unit 3: This is where the story has a happy ending. Get unit last night from florida. Claims unit won't power on. Seller immediately lets me know shipping will be a day late, wifey forgot to slap on shipping label, and he was late for work. Shows up last night. Well I open the unit planning to swap parts. This is an older unit with the 1/8 old skool plug power adapter and socket. The headphone shaped one. The jumper from the PCB to the socket broke. solder a new one it, unit fires up first time. Pots are a little scratchy, otherwise like brand new. Ever had bought something "broken" only to find it one loos connection? SCORE!!!