Sega lamp matrix question

[aaronhicksuk]

presumably also caused by the failing transistor?

when it comes to soldering, i'm ok when i can hold the iron in one hand and either the sucker or the solder in the other, while gravity keeps the bits in place, so boards i can usually have a decent effort at. but when it comes to a simple wire off a coil/switch, i just can't do it without an extra hand to keep the ****ing thing where i need it to be while i'm soldering. i end up with balls of solder falling god knows where and causing mayhem, huge regmaglypts of cold solder, and nothing holding fast. i need an extra arm, dunno how you guys do it

Its definitely a lot more awkward then reworking a board on a bench, its a shame we only have 2 and not 3 or 4 hands! I find preperation is key. If you're trying to solder 2 or more cables to the same lug then they really need to be joined together first, otherwise its very difficult to keep everything in position. I normally cut the soldered ends off and strip back to clean wire. This allows you to twist all the ends together and tin them up so you can grab hold of them as one piece. Make sure the lug you're soldering to is clean and well tinned also. If theres enough solder on the lug you can normally just reheat and move the wires into the pool.

Possibly the best tip I can offer though: When you tin up either the lug or the wire, remove the iron but hold the length of solder in place so that the it stays attached when it cools. You can then cut off however much extra you think you'll need to flow into the joint. This way when you flow the final joint you only need to hold the iron in one hand and the wire/s in the other.

I picked up one of the these things free at the UKPP this year which comes in handy sometimes too as you can wedge the base into the loom or wrap the gooseneck around something and hold parts in place:

 

[aaronhicksuk]

@astyy - Regarding your problem, the parts you're looking at there are at the very end of a chain of transistors and appear to be mounted to a separate high current driver board. You need need to check for faults and pay attention to everything either side of it in the chain. The coil and playfield wiring as well as all of the pre driver transistors and associated components on the the CPU board. If this coil locked on before then all of the transistors in the chain will have been stressed. Did you replace everything in the chain before? If you didn't most likely one of the stressed pre-drivers has now failed and caused your current problem.

 

[cooldan]

hold the length of solder in place so that the it stays attached when it cools. You can then cut off however much extra you think you'll need to flow into the joint. This way when you flow the final joint you only need to hold the iron in one hand and the wire/s in the other.

I remember seeing you doing something like that when you were fixing the ramp switch on Creech at NLP, I meant to ask you about that. Next time I see you I'm gonna ask for another demonstration I think. Cheers buddy

 

[aaronhicksuk]

Yea that ramp switch on your Creech was espeically awkward because the wires were short and it was sandwiched between 2 plastic ramps! It took the hands of both @ronsplooter and myself to hold it all together and solder it in mid air!

I'll see if I can do a little video demonstation the next time I'm soldering. I'm coming to the end of my STTNG restore and have a few bits left to do so shouldn't be too long away.

 

[astyy]

@aaronhicksuk thanks for the advice. This was an ongoing fault when I first got the machine that was coil locking on, then Q4 and its associated fuse blowing. I finally narrowed it down to the coil which was seemingly testing good but obviously not when being exercised. I didn't change any of the other parts including that Resistor and the pre-driver on the MPU and I blew several TIP36Cs whilst t/shooting. I'll carefully examine the bits you mention as I want this working for Chrimbo as non-Pinheads just love a bit of HOOKy!