Pressure on RF shield plate freezes/glitches Turbo Duo!?

[jasonbar]

Long story short:

When I apply any pressure pretty much anywhere on the rear 2/3 of the large RF shield that covers half of my US Turbo Duo PCB, the system will glitch (solid blue screen on power-up, graphics glitches, freeze, etc. etc.).

Solution: I removed the large RF shield altogether & it's now working perfectly.  I also soldered the 2 ground wires (for CD drive & for power supply) to the small vertical RF shield at the back of the unit.  While posting this, I came across this picture: http://i130.photobucket.com/albums/p266/Rockguard/PCEngineDuoTotalCapReplacementRefer.jpg  Hey, my unit looks just like this one now, so perhaps I'm not the 1st person with this problem.

What's the story?



Long story long:

I performed the region mod with an 8PDT switch.  All worked perfectly while the system was decased.  After assembly, the system rarely worked.  I'd usually get a solid blue screen when a card was installed.  CD performance was more consistent, but still not quite right.  I put the 8PDT switch in the same spot as shown here: http://www.multimods.com/images/PCEDuo1b.jpg.  (I decided upon this location on my own--guess it's a popular spot, as it seems to be the only location where this switch can be fit!)

After decasing & recasing many times & realizing that the system worked fine when disemboweled, I figured that I was getting a short in my region mod switch wiring when the case was assembled.  Sure enough, pushing on the switch (while it was sitting on the RF shield) made the system glitch.

Further study revealed that the system glitched not when handling the switch on its own, but when pushing on the RF shield.  Through several experiments, I realized that, when pushing on the RF shield in pretty much any location on its back 2/3, the system would freak.  I tried pushing with a piece of rubber, wondering if I wasn't grounded properly, & the result was the same.  It's pressure, not shorting/grounding.  So, perhaps a cold or cracked solder joint somewhere???

So, I removed the RF shield, grounded the 2 aforementioned wires to the small rear shield, & used the same piece of rubber to push all over on every spot on the PCB itself while the TD was powered.  Not one glitch!  If I had a bad solder joint somewhere, pressing directly on the PCB would cause a glitch.

What gives?


Thanks,
-Jason

[BlueBMW]

Only thing I can think of is maybe pressing in multiple places at once (as the rf shield might be) might cause the right kind of flex to cause a solder joint to open.

[Turbo D]

What gives?

mod/reassembly fail

 

[Charlie]

underside of shield shorting to a tall component/connection?
Charlie

[jasonbar]

@BlueBMW: I dunno...it's weird--that RF shield anchors to a small vertical RF shield in the back of the console, one of the 2 card port screws, & the controller connector.  When I remove the RF shield & press on those points with an insulated piece of rubber, I get no glitching.

@Charlie: possibly, but best I can tell, there's plenty of clearance.  Odd, the more that I look at the pic at http://i130.photobucket.com/albums/p266/Rockguard/PCEngineDuoTotalCapReplacementRefer.jpg, the more it appears that the Duo in that picture never even *had* the big RF shield that's on my machine--the Duo in that pic would have bent arms on the rear shield & some solder markings on the controller port housing if it had previously had the big RF shield.  Plus, my Duo doesn't have the small shield over the card slot.  Kooky.


Thanks,
-Jason