Traces lifted (but still connected) on neckboard - WG K7401

dukesilverfan

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Traces lifted (but still connected) on neckboard - WG K7401

I was about to start my cap kit last night, when I noticed the transistor heatsinks seemed loose. I quickly discovered that all 3 had lifted the traces on the backside. They are still connected, and the monitor still worked before I pulled it apart, but the colors would sometime cut in and out. This is probably at least partially responsible.

Here is a short 8-second video I took:
https://dl.dropboxusercontent.com/u/18769305/lifted_traces.MOV

As you can see, the traces are still whole, they just lifted up off of the board. Should I try gluing them back down? Will superglue hold up to the heat created?

What would you experts do, please advise!
 
try this: http://www.organizedmassconfusion.com/wells-gardner-p719-neckboard/

this is done to tack the traces back down. the reason this happens (may or may not be mentioned in the guide -- I made that years ago) is those heatsinks aren't very good at their job. the heat traps against the neckboard and the traces lift.

when you're done with your surgery, there's 3 large resistors below the transistors. space those out. being one on top of the other just builds more heat. your monitor will smell like boiling rice when this happens. I did it on my new 7400 and it just smelled hot -- spaced those out and it never did it again.

so I almost wonder if it's the resistors at fault more for the excess heat. I saw one of these neckboards under a FLIR gun and it's actually amazing how hot they get.
 
since they are weak and its tough to glue them down and make them hold after you have applied the soldering heat to them i would suggest installing them and running a jumper from each leg that has the loose solder pad to the next component/solder pad. you do have an option of cleaning the trace and soldering it to the trace directly. you can use quality clipped legs from caps or zero ohm jumper wire (i stock that) or regular wire but make sure the wire jacketing doesn't melt or shrink when heated if your crossing traces or put shrink wrap over it once you have soldered one side down.

if this was a resistor tight to the pcb it may hold the loose pad without all this work or if you had one of the larger wattage resistors common on the neck pcb's of chassis you could kink the leg on the component side so it can't push through to the solder side any further and solder the pad tight on the other side.

if you pads/traces are cracked or not whole then you have to bridge to the next location otherwise you will be fixing it again later.
 
Thanks everyone, I am glad to see this isn't completely out of the ordinary. I will remove the transistors and re-install tight, and then check to see if I need to jumper the pads or not by checking continuity afterwards.

While I am in there doing this, would there be any harm in adding some sort of glue to beneath the trace? Should I add any sort of RTV or something to the heatsink?
 
the totally sadistic way I fixed my U5000 neckboard years ago lol. I mainly did it this way cause I could. :p today in my more advanced age I don't find any shame in just running wires between points.

373974_10100311769473579_334951403_n.jpg
 
well, funny story about that U5000. we got a pair of Blitz 99/2000s at an auction; the one with the K7500 had the flyback and contrast on max, it was just a pink blur of a screen. that tube was pretty well screwed. I had it rejuved and it didn't stick, it reverted right back to having the red stuck on slightly and weak green. the U5000 in the other one though seemingly appeared just fine for a time until the primary colors started dropping out. mind you I had just ventured into tinkering with monitors that year, so this is when I learned about the trace lifting issue. I tried just reflowing solder, that seemed to be ok, and then I discovered the red was weak.

I had that tube zapped next and for whatever reason the red was still weak. that repair you see was for the red. so while the red emissions were bad, that transistor had all 3 traces dinged up. I would guess a couple of them had to make a somewhat connection to see a faint red.
 
yup, normal om those neck boards.

i just jumper them if they are to bad and will not glue down.

if you need the neck board fixed up, your welcome to send it in.

Peace
Buffett
 
I took mecha's advise and pulled the transistors, and then re-installed them tightly by bending the legs over before soldering. The traces are lifted off quite a bit, but I checked, and then double checked everything with my multimeter, and everything has continuity. I think it will hold up nicely. If not, I will add in some jumpers to do the job, but until then, I think I may have put some life back into this board!

The picture may make it look my my joints are bad, but they are actually quite well done. I have a nice Hakko iron and some skill. Most of what you see is just the flux burning, and the burns on the pcb that were pre-existing. This is an improvement over what it was!
traces.jpg
 
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with traces flapping in the wind like that i would put jumpers on it because you will be doing it later if you don't.
 
the wiggle test. wiggle the heatsinks and see if anything moves. if it does, then you didn't do it tight enough. :)

also, the large resistors below those, space them out.
 
the wiggle test. wiggle the heatsinks and see if anything moves. if it does, then you didn't do it tight enough. :)

also, the large resistors below those, space them out.

Done and done! No wiggle, and spaced the resistors. I'll still probably glue down the traces instead of running jumpers, I can always fix it later if I need.
 
Just as an update to this, I have my MK2 cabinet back together with this monitor installed after fixing the traces and doing a cap kit, and it is FANTASTIC. The colors are all perfect, and everything adjusts just as it should. I couldn't be happier with how this first monitor project turned out!
 
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