looking for someone that repairs arcade boards

[ChadTower]

Yeah, that chip is by far the worst thing on that board to try and replace.

[berlincam86]

Yep that looks like the board i have and i havent messed with the dipswitches. I paid $50 for mine and i cant find anymore at all on e-bay.

[shardian]

Yeah, that chip is by far the worst thing on that board to try and replace.

[ChadTower]

I mean, really, that chip is harder than the other stuff.

[psik0tik]

Then there ya go it may be cheaper to buy another off of ebay. Withthe chip and cost to have a new chip soldered on it may be over 100.00.

[berlincam86]

yep ill be looking for another on e-bay.

[psik0tik]

Or look in buy/sell/trade on here and ask if anyones got one..it may be safer than buying on ebay. And you may get it a litter cheaper or may be able to trade some stuff out.

Thats an idea...Saint should set us up our own little auction thing.

[berlincam86]

I will try that.Thanks.

[Jess--]

I have a fully working police trainer board sat in my bits box, I would say make me an offer via PM but I suspect that shipping it would be a deal killer as I am in the UK

[MonMotha]

If you want some more insight into soldering that thing down, I can offer my experience (yeah, I've soldered stuff like that).  The process is generally very time consuming and tedious, but tends to work well.  If that's the 0.5mm pitch, that's the toughest kind, but they're doable.

A temp controlled iron with a decent tip is a must for this, but you don't need to go incredibly fancy and get a top of the line Metcal.  Hot air helps, but isn't required.  I use a Weller WESD-51.  Set your temp reasonably.  You want it hot enough to flow solder rather quickly, but not so hot that you're burning the board up.  I usually stick to between 300-350C.

Getting the old chip off is easy.  Just take a sharp knife and shear all the pins off of the package, being very careful not to cut into the board itself.  Then take your iron and "wipe" the leads off the pads.  Be careful that you let the lead/pad warm up before applying any lateral pressure, otherwise you'll tear the pad off the board (and that is not easily repaired at all).  I've had good luck intentionally getting the leads to stick to my iron, then wiping the iron on the sponge to remove the leads.

To solder down chips like that, I generally flux the row of pads and drag solder, then clean up the excess flux and use solder wick to remove bridges.  Basically, you apply flux to the bare board along all the pads not worrying much about where it goes since the soldermask will usually keep most of the solder in the right place.  Position the chip (this is BY FAR the hardest part) and tack down the corners.  Then you get a SMALL "blob" (just a little drop) on your iron and drag it gently along the very edge of the lead/pad interface.  The flux will suck the solder in and form the joint.  With a little practice, you can get the angle on your tip and your drag speed just right so that you won't form too many bridges.  You'll have to back off and apply some more solder to your iron tip frequently (the people who are really good at this can feed the solder in as they drag).

You'll have some bridges, so clean up with solderwick, then use either flux remover or simple rubbing alcohol to remove the excess flux (there will be tons) before it dries.  A visual inspection (possibly with extensive magnification) for bridges is usually more effective than attempting to electrically test.

1-0.8mm pitch is really easy with this method, but 0.5mm pitch can get a bit tough.  If you want, you can also try reflowing, but you'd need a stencil to get the solderpaste on cleanly enough to prevent bridges.  Reflowing does make positioning easier as the surface tension of the solder/flux tends to help center the chip on the pads.

Suffice to say, if you have trouble soldering big stuff, this probably isn't even worth trying - get somebody else to do it.  If you mess up, you'll likely destroy the board and/or chip in the process.

[berlincam86]

Sounds good but the problem is i cant find a new chip. Any ideas where i could get one?

[MonMotha]

Heh, good point - I didn't really address that part.  The easiest way to find one would be to take it off another board, hence people recommending you find a non-working one "for parts". 

However, removing a chip like that without destroying it is even harder than soldering it down.

I've heard very good things about "ChipQuik" desoldering kits.  They come with a very low temp solder that you gradually replace the existing solder with (by wicking almost all of it out then adding new and repeating a few times).  Eventually, you'll get to where you can get the whole thing to flow at once with a simple hot-air soldering tool, and you use forceps to just lift it off the board.  These kits aren't overly cheap, though, at around $35-55 at Fry's or online.  You'd probably need a hot-air gun for this, though a cheap heat gun on low might suffice in a pinch if you're cheap.

Of course, all that is much easier said than actually done.  I've never had to attempt something like that, so I can't really say much.  Figure you will at least somewhat damage the board you're removing the chip from due to the heat, but you shouldn't care too much if the board is otherwise non-functional.

The rule of thumb is that you can either remove the chip in one peice while toasting the board, or you can remove the chip in an unusable state without damaging the board, but not both.  Trying to do both usually results in damaging both parts.

Taking the above rule to the extreme, I have heard of people cutting the board around the chip of concern, then mounting it upside-down in a toaster ovenwith a tray right below to catch the chip.  You then heat the board to the point of reflow and hope that everything reflows at about the same time (hint: it usually doesn't).  If you get really lucky, the chip just falls off the board.  If you're not lucky, the chip partially falls of, bending a bunch of the pins on the part that hasn't reflowed yet.

[berlincam86]

Sounds like fun either way. Ill just try to find a cheap board that that chip works in and tranfer everything else. To the guy that has one i sent you a pm let me know if you got it.

[D_Zoot]

Sounds good but the problem is i cant find a new chip. Any ideas where i could get one?

Those custom SMT IC's are impossible to source.   I've got a whole box of different boards with bad custom's (mostly damn Konami boards) that I've relegated to parts board duty.

Good rule of thumb, bad SMT custom IC's = easier/cheaper to find a working board.   Trust me, I do board repairs and even I won't bother with these for my own route machines!!!


D