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  • Joined: 28 Sep 2022
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Shielding removal VA2 PAL Mastersystem 1
Post Posted: Wed Sep 28, 2022 8:05 pm
Hi,
Is the shielding necessary on the VA2 PAL masterysysem motherboard - the area that covers the crystal, 3 ICs and a few passives?
I want to remove it due to a faulty/marginal component beneath it but it is very hard to de-solder due to the amount of old solder present.
I am tempted just to cut it and remove it.

Will this cause me issues?

Thanks!
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  • Joined: 14 Aug 2000
  • Posts: 702
  • Location: Adelaide, Australia
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Shielding removal VA2 PAL Mastersystem 1
Post Posted: Wed Oct 05, 2022 5:37 am
The circuit under the shielding is the clock divider that generates the 10.7MHz for the VDP, 4.43MHz for the colour subcarrier, and the 3.55MHz for the CPU, from the 53MHz crystal.

I have never seen anyone remove it or try to run the Master System without the shielding so I can’t say if there will be issues or not, but I imagine that the engineers put it into production for a reason. If you do remove it you could always put it back again.

What makes you think the components underneath are marginal?
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  • Joined: 28 Sep 2022
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Post Posted: Wed Oct 05, 2022 8:01 am
asynchronous wrote
I imagine that the engineers put it into production for a reason. If you do remove it you could always put it back again.


Yeah, that was my thought, but then again, all 80s stuff has a lot of compliance shielding that is now unneccesary (c64, megadrive, etc all run fine without their rf sheilds).

It is so tightly soldered on my mastersystem though, I struggled to remove it. If I cut it off, it would be very hard to put back on.

asynchronous wrote
What makes you think the components underneath are marginal?


At the time of writing, there was no clock signal coming out -- there is no clock signal either on the Z80 clock input or on the 315-5124 input or output.

After heating the board to try and remove the sheiding, the clock signal miraculously returned (was using a heat gun and soldering iron to try and remove the solder around the shield tabs).

I think I've either ended up reflowing a dry joint somewhere in the clock circuit or the heat has temporarily 'repaired' a faulty component that will fail again before long.
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  • Joined: 05 Jun 2010
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  • Location: Pennsylvania, USA
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Post Posted: Wed Oct 05, 2022 12:52 pm
Leave it powered on for more than 24 hours with your temporary repair and see how it holds up. If it passes that test, then maybe it was dry solder joint.

But yes, probably just extra RFI stuff. Might make it not work so well with RF, but who uses that any more?
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  • Joined: 18 Mar 2019
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  • Location: Brighton, UK
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Post Posted: Sat Oct 08, 2022 8:04 am
RF shielding in electronics is there as an FCC requirement to reduce the EM noise that a device produces.

Most consider the legislation to be a massive overreaction and the shielding itself can be removed. It won’t effect the performance of the device as it was never intended to. It’s to stop interference getting out not getting in.

Shielding makes sense for high power high frequency devices but for domestic electronics it’s almost completely unnecessary.
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Post Posted: Tue Oct 11, 2022 12:44 pm
kejoxen wrote
RF shielding in electronics is there as an FCC requirement to reduce the EM noise that a device produces.

Most consider the legislation to be a massive overreaction and the shielding itself can be removed. It won’t effect the performance of the device as it was never intended to. It’s to stop interference getting out not getting in.

Shielding makes sense for high power high frequency devices but for domestic electronics it’s almost completely unnecessary.


Massive overreaction with the Vectrex for sure. Even causes the infamous Vectrex Buzz because of it.

With that said, I think the only reason it could be necessary to keep it is that removing it might make the RF adapter work poorly. The RF adapter box is already sealed with an RF shield itself so it should be a non-issue; but worth checking if you care about using that over RCA/S-Video/SCART/RGB.
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