I would clean the pads off with solder wick then position the new part and juat solder it straight onto the board. Forget about leaded solder. It will make zero difference to your repair.

I wouldn't be using a heat gun anywhere near this board. It is far too tightly packed.

All the parts close by will start coming off. I wouldn't use it you risk destroying the board. Three pads is a doddle with a soldering iron. Simply no need for a heat gun here.

Thanks for starting a productive thread rather than the "sky is falling" thread the other one turned into.

We repair boards like that all the time with hot air. Not a big deal with a pre-heater, the proper nozzle, programmable rework station and some heat shielding.

Most hobbyists aren't going to spend that type of money though so you have to get creative. Chipquik is like magic or in the case of the FET's hot tweezers in one hand and soldering iron in the other would work pretty well. Or the OP did just fine without any additional equipment.

For those not familiar with Chip Quik.

I put this in the other thread, and it probably should be here for those learning to deal with SMT (Hope you don't mind me expanding your thread to include tips and tricks.)

Ceramic fiber non-woven shields and Kapton tape work great for creating heat dams and protecting adjacent components. Here's some info on the shielding effectiveness for anyone interested.

http://circuitsassembly.com/ca/magazine/24290-rework-1410.html

Leaded solder will make the job (and risk to adjoining components) much easier since lower soldering temps are required. In fact I would recommend people new to SMT not use unleaded solder.

Yes. I meant that to use leaded solder would be a good thing so forget about worrying about it.

Rock on swinks!

Was hat with a fine tipped iron or the heat?

Yeah, I've been working with surface mount since those little led's came out. Your son? mods those controllers right? stuff like that. Once you get the right iron, it is sooooooo easy.

Nice work and thanks for sharing.

Hello
I recently fixed the main board that had lost the 9V power for the node bus communications. All the power status LEDs were lit apart from the 9V. I think the transient suppression diode D4 must have gone short circuit and taken out the regulator chip U10. Changed those two components and all has been OK since, that was maybe 6 months ago.
The only difficult bit was removing U10. This chip has an exposed metal-base that mates with a heat-pipe on the circuit board, as the photo shows. I think perhaps these are bonded together with a thermal type epoxy glue and hence a little difficult to separate!
I've got SMD rework kit but this was easily done with some fine side-cutters and traditional soldering iron fitted with a tiny tip!
Cheers bob

2016-12-17 11.49.05 (resized).jpg

Thanks for putting this thread together TB my wrestlemania is dead an have no idea how to get it going, I'm going to take it to Zax amusements to look at it because no one around here has a clue about the new spike system, but will post the outcome when it comes back.

Hi All

Perhaps I should elaborate as to how I worked out the faulty components, as this may help others with similar situations.

There are four status LEDs that indicate the four supply rails are present, 5V, 9V, 24V and 48V

Looking at the board there are four identical chips with identical components around them, so I figured they were the controller chips for those supply rails. Its the usual switch mode circuit comprising controller ic & it's inductor/capacitor. Looking up the data sheet confirmed this and provided the pinout, to see which pin is the output.
IIRC even the 48V rail is again regulated on the board, despite the overall 48V power supply.

Now the 9V LED via its current limiting resistor is always going to be strapped across the monitored voltage rail and ground.

So with my multi-meter set to continuity-bleep I probed around the outputs from the four regulator chips to the 9V LED until I found the chip that was connected.

To prove this further I did the same for the other LED voltage indicators to the other chips until I was happy that each chip accounted for a particular supply rail.

Next the suspect regulator chip I measured its output resistance to ground, a direct short!

IIRC there's also a large through hole capacitor as well as the transient diode in parallel to the output of the 9V regulator chip U10, so either could be responsible for the short to ground. I figured removing the diode was easier and less likely to damage the PCB. However the short was still present, next I checked the diode with my meter set to diode check. This diode D4 was short circuit!

Same thing again I figured its easier to remove the chip then the cap even though I’d have put money on the capacitor being bad. Once the regulator chip was removed, the short was gone.

While the capacitor was effectively out of circuit I tested with an ESR meter which showed the capacitor to be OK

Then it was a case of soldering in a new chip and diode. Powered up and 9V was good.

Good idea to by some really fine soldered as well , I used some 0.3mm diameter

Cheers Bob

Wow this is great. I know Rob Anthony said hes been able to fix them as well. My guys have not had much chance to work on any but I have 2 guys who do quite a bit of surface mount work and 1 guy who does it less often but is able too.

I have not used this but I was going to buy one to give it a try but here is a hot air rework setup. for pretty cheap. Did some looking around and it had decent reviews. Not a hard core setup but for hobby work should be ok.

https://www.walmart.com/ip/Pro-Tech-853D-SMD-DC-Power-3in1-Hot-Air-Iron-Gun-Rework-Soldering-Station-Welder-6-Gift/111981731?u1=aa9aa51a7e0711e7a7a152891ca1aa110INT&oid=223073.1&wmlspartner=lw9MynSeamY&sourceid=19864510413606151651&affillinktype=10&veh=aff

I have an older (non digital) version of this one that works well for me:
https://www.circuitspecialists.com/hot-air-rework-soldering-station-csi900+.html

The pump in this one is in the base unit. It's not clear on the one you referenced how the hot air works.

Edit: They go on sale occasionally if you sign up for their emails (they're good about not sending too many).

ChipQuik (http://www.chipquik.com/store/) is very handy for surface mount work if you don't have a rework station.

BURNT CHIP!

I purchased a HUO Ghostbuster Premium the other week - been having fun on it, and I woke up this morning to half the playfield being dark (I left machine on overnight) - the diagnostic failed Node 9 board. I did some searches and decided to pull the board after reseating the cat5 connections (didn't work) - and was going to swap with Node 8 and see if that told me anything. Before I did that - I noticed on the board that a whole chip had fried. I'm posting pictures here. Any advice on getting it fixed, or talking with Stern? Thanks!

GB Board Full (resized).jpg

GB Chip Close Up (resized).jpg

GP Node 8 Good Chip (resized).jpg

GP Node 9 Burnt Chip (resized).jpg

GP Node 9 Burnt Chip Barcodes (resized).jpg

Was this the mode board that had a tsb for having the Ethernet pulled too tight? Anyone remember?

Not sure about the Ethernet one, but this one was to do with the diode breaking off
https://sternpinball.com/wp-content/uploads/2018/10/Stern-SB189.pdf

Another Node Board saved! Q10 crapped out and I was able to successfully repair it thanks to this thread. ChipQuik made life much easier. Game is working perfectly again.

8133F55E-04ED-4C84-B721-925DAE18CFB9 (resized).jpeg

5709232D-CFFC-4BF5-ACDF-44F93C755379 (resized).jpeg

General question - other than being able to see a chip being visibly fried, how would you know where to look if a chip went bad? How would you know what to test?

Are there any instructional resourced out there? I’ve already done a hot air solder repair on an LED on one of my boards, so I’m willing to learn more advanced repairs.

Increased reliance on these boards means general repair skills on these boards is becoming a “must” in the hobby.

Start with a board schematic and the datasheet of the chip you want to test so you know the pin assignments. You can use a logic probe or oscilloscope to test the various inputs and outputs once you have a general idea of what they should be doing from the schematic.