MVS capacitor desoldering

MtothaJ

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I took a first attempt at replacing the caps on my MV-1FZ board today and am having a real hard time desoldering the old caps.

For the first try I chose a remote cap near the JAMMA edge with little in the way of components in its proximity - basically its a no go, whatever I try I cannot get the solder molten enough to set the cap loose. I do not have a dedicated desoldering tool like e.g. Hako FR-300, but with the tools I have (WEP 872D soldering / hot air station, manual desoldering pump, desoldering braid etc.) I cannot make any progress on removing the old caps, let alone clearing the via's up for insertation of the new caps.

I tried all the usual methods - apply new solder to the old joints, using different tips (e.g. needle to pry the via), preheat area with hot air to reflow the old solder etc. but ain't making any progress.

It seems the extensive PCB thickness is part of the problem. The other week I replaced the caps in a PCE Supergrafx and SNES Mini and just now finishing up doing a model 1 HDG Megadrive - these were all relatively simple jobs but this is proving really difficult - any ideas would be welcome.
 

Niko

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What temp are you running your iron at?
 

MtothaJ

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I tried up to 480C with the needle tip (really thin tip so doesn't transfer all that much heat). With the chisel tip I was running around 330C. I have another iron which can go higher temps, but kind of reluctant to use it for fear of damaging the through-holes / via's.
 

GohanX

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I used to have this problem when trying to do work on thicker boards like the two slots when I was using the crappy Radio Shack equipment. The problem was that the PCBs were drawing the heat away from the iron tip faster than the iron could really reheat it. It didn't matter how hot I had the temperature set at, the irons just couldn't keep up. The fix for this was buying Hakko equipment, which I can keep at a lower temperature but it has no problems maintaining proper heat.
 

NexusX

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One of my last ditch efforts is to apply flux to the underside of the board and apply hot air to the 2 cap solder joints until the solder flows and you can just pull the cap out. It is a bit extreme and it does dump a lot of heat on the board while yanking out the cap. Hence last ditch effort.
 
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awbacon

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the board is sinking all your heat so you won’t get the solder to go molten unless you A) up temp or b) upgrade equipment.
 

MtothaJ

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Many thanks for your helpful hints guys. The comments about my iron being shitty and the board absorbing all the heat were real. I borrowed a different iron and had absolutely no problems is desoldering all the caps using flux and solder braid - board is currently decapped, new caps on order, so will probably finish this one off at the weekend.
Just kind of disappointed that my soldering station turned out to be a pos. Granted, you get what you pay for and the hot air section seems to be decent enough but as for the soldering side of things that thing is a fail. Guess I will just need to pony up and get a Hakko at some point.
 

wuemura

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To cases like this you need to preheat the PCB, that is why we use pcb preheater. If you just apply heat to the PCB it will warp and curve upwards, not only that, you can start a delamination process that could break the tracks and pads in between the layers, that is why you have to take thermal management of the materials your are working with very serious.
 

MtothaJ

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To cases like this you need to preheat the PCB, that is why we use pcb preheater. If you just apply heat to the PCB it will warp and curve upwards, not only that, you can start a delamination process that could break the tracks and pads in between the layers, that is why you have to take thermal management of the materials your are working with very serious.

In all honesty, a decent iron and some soldering braid is all that's needed to replace the caps on MVS. This is all that I used, no pads lifted, no damage to the board and traces:

thumbnail_2019-06-07%2012_25_51.jpg

I managed to return that pos WEP soldering station and this time I will shell out a bit more and buy something decent.

PS. what is the deal with the stock caps being covered in hot glue? I had this on my board and also saw something similar on another MV-1FZ board so inclined to think it was standard practice.
 
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wuemura

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Nice!
I rather prefer to use a electric desoldering pump, it is the best investment I did. With it I can remove those caps in seconds, precise, fast and clean.
 

Atro

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for cases like this, I just don't bother.

I just cut all the cap legs. heat the solder base while gently pulling the leg with another tool. the surface is then clean enough to remove the remaining solder with either the electric pump or the manual one, rather easy.
 

MtothaJ

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for cases like this, I just don't bother.

I just cut all the cap legs. heat the solder base while gently pulling the leg with another tool. the surface is then clean enough to remove the remaining solder with either the electric pump or the manual one, rather easy.

At least on the MV-1FZ board the problem is there are no legs to cut - the bottom of the caps touches the board - same as in the pic of the recap I inserted in the previous post. You really need to remove all solder first and then make attempts at removing the cap otherwise one will end up with ripped pads.
 

Finch

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In all honesty, a decent iron and some soldering braid is all that's needed to replace the caps on MVS. This is all that I used, no pads lifted, no damage to the board and traces:

View attachment 54232

I managed to return that pos WEP soldering station and this time I will shell out a bit more and buy something decent.

PS. what is the deal with the stock caps being covered in hot glue? I had this on my board and also saw something similar on another MV-1FZ board so inclined to think it was standard practice.

Is it dumb to want to know what brand those swanky gold caps are? looks very cool.
 

Misos

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Necro Bump.
I have a similar solder station that OP have and I'm having the exact same problem with desoldering the caps, ground pads in special.
Would a Hakko FX888d do the job? With a T18-d32 chisel Tip.
 

CloudGamerX

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Necro Bump.
I have a similar solder station that OP have and I'm having the exact same problem with desoldering the caps, ground pads in special.
Would a Hakko FX888d do the job? With a T18-d32 chisel Tip.

Honestly, for arcade boards, your best bet is to get your hands on a good desoldering tool. I personally use the ZD-915, set to 360°C
 

Heinz

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I had a tough-ish time with my Weller WESD51 but never really thought to go higher than 320C, maybe I should've upped it.
 

GohanX

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Necro Bump.
I have a similar solder station that OP have and I'm having the exact same problem with desoldering the caps, ground pads in special.
Would a Hakko FX888d do the job? With a T18-d32 chisel Tip.

I have an older model of that Hakko, it does great work. I'm not sure what the exact size I have on it, but the chisel tip is my preferred tip for most things. That said, CloudGamerX is correct. I use a FR300 desoldering gun, and it's expensive, but the time savings on the first major job makes it well worth the expense. Then being able to do something simpler like a complete refurb of a Genesis 2 in 15 minutes is a joy.
 
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