Help with desoldering Dreamcast BIOS

I've only recently picked up a hot air rework station (one of the 858D clones) and am having trouble removing a BIOS from a Dreamcast. At the moment I'm running it at 400 degrees Celsius with the fan set to 5 using the smaller blower tip it came with.

The first DC I worked on had some massive issues where I accidentally picked up the pads the BIOS solders too (I suspect I overheated the PCB and had the blower too close to the PCB). I've since practised on some spare/dead PCBs and seem to be doing better - no issues removing SMD resistors, small SMD video encoders but still had some trouble with tight pins on some SMD gear; had great success working with solder paste as well. However, I'm paranoid about flowing too much heat to the PCB and affecting the thermal adhesive on the heatpipe blocks on my VA0 DC's CPU and GPU.

For those using hot air stations, can you provide some advice? Particularly around distance from the PCB, temp, fan speed and how long you heat the chip before you try removing it? I've looked at the 858D clone video from EEVBlog on YouTube and the ICs seem to come off really easily so I'm not quite sure what I'm doing wrong at the moment.

 

You can remove the heatsink setup on a VA0 to have better access to the chip. Use plenty of flux.

 

As Ergot said, use plenty of flux and remove the heatsink.
What size tip are you using? I would use the next step up in tips as it may help you more.
And heat around the chip where the pins are, keeping the tip moving along the pins. From end to end then repeat on the other side. Almost like a circular motion.
I start at about 1inch from the ic then work my way closer while maintaining the circular motion.
As far as temps go, I don't go that high for an ic that size. I'm at about 300-330c with the fan speed at around 5 or 6. But it'll differ for you.
If it still proves difficult, I would suggest some chip Qwik or any other low melt alloy.

 

Thanks guys, I’ll give it a whirl.

2 follow ups - how long is safe to be applying the hot air to the PCB, does it typically only take a few minutes? And for removing the heat sink, how do I remove then re-attach it afterwards? I’m assuming I can pull it off the ICs, but I’m unsure how to re-attach. On my test DC the adhesive on the heatsinks came loose so keen to get this one right

 

What are you using to lift the chip after heating it?

 

I recommend dental picks.

 

That's a good point. I've got a mini vacuum tool but the issue is creating some leverage between the PCB and the IC. I've also tried ESD tweezer. Is it expected to use something to lever it off once it's heated up? When I was using the hot air station on smaller ICs I could use my ESD tweezers to pick them up, but with the volume of pins and the size of the IC, I'm taking it from the above I should be using something with a little more grunt!

 

You shouldn't be applying any sort of force to lift it. I use a $1 vacuum pickup tool just fine many times per week; try watching some Youtube videos or something. The only time I ever had issues is with Sega Saturn BIOS epoxy which required a bit higher temperature than usual. Can't imagine what you're doing wrong, go back and forth on the leads for about a minute (2 -3 inches or so above it in a circular motion, don't heat the same spot) after heating the chip directly at 380C 4 on dial for airflow (I used to use the same station) then push the button it, press it on top of the chip, release button and lift. Should pop right off.

One thing you may want to check is if the rubber piece is too far up on the metal shaft and not creating a seal. They are cheap pieces of junk but work when you know how to use them properly. Press the trigger in, try to pick up a random IC or something and it doesn't lift it then slide the rubber piece down a bit further. Not sure what else to say

 

I tend to just put a small amount of pressure as heating it up (you need to get the knack of this, too much will rip off pads). You can feel when the solder has melted and can just take the chip off.

I don't use vacuum tools for hot air rework. Only when using ir Bga rework station

 

Found this on Youtube, looks pretty comprehensive. Same process just imagine it's your Dreamcast board.



Man this is great, way better than my crappy thread I made. Must have a day job in some sort of video production.

 

Thanks everyone for the extra help, especially that video from Voultar. Had another crack at it last night and am really happy with the results - took around 3-4 minutes with the hot air station on 340 with air flow of 4, slipped my ESD flat tweezers under the IC and it came off super cleanly. Scrubbed with some iso and used some fresh flux and wick, the PCB looks super clean and ready to go.

In terms of fitting the BIOS to a VA0, in my notes I've scribbled I need to lift pin 1 and solder to B14 near the GD ROM connector, solder all the other legs to the pads and then solder an extra insulated wire to connect pins 23 and 44 together. Does this check out?

 

You don't need to lift any pins. Connect IC501 pins 23 and 44, then connect pin 1 of IC501 to pin 7 of IC502.

 

See above. Only lifting pins when doing piggyback. Direct replacement you don't need to lift them as they don't connect anywhere on the dc pcb, they are just pads connected to nothing.

 

Sorry for the belated response - wanted to say a huge thanks again for that last round of advice, very pleased to report it seems to be working beautifully! My only issue now is getting a fresh cap for the power supply - have just converted the 100v Japanese supply to 240v using the cap/resistor swap and the Nichicon cap I picked up was the wrong height (30mm high instead of 25mm), so once that’s in later this week I’ll be able to close it all up and enjoy the region free BIOS!