Zero ohm resistors?

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BigSteve
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Zero ohm resistors?

Post by BigSteve »

Is there any purpose to the zero ohm resistors other than manufacturing convenience?

I have an STFM board (C070789 Rev D) that I want to fit the HD (floppy) board and the row of resistors that appear to be 'links' (L5 to L11) to the parallel port) are interfering.

Can I simply replace these with links ensuring they don't short to the ground trace below? I note that 'L' for component shorthand often indicated an inductor. Does this apply to Atari?

TIA
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stephen_usher
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Re: Zero ohm resistors?

Post by stephen_usher »

Yes, you can just replace them with header pins and a jumper.
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Re: Zero ohm resistors?

Post by exxos »

They used to be RF filters in a 3 pin package. Atari used zero ohm resistors on later machines. You can wire link them instead just be careful not to short to the center pin as its gnd .
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sporniket
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Re: Zero ohm resistors?

Post by sporniket »

BigSteve wrote: Sun Jun 26, 2022 1:52 am Can I simply replace these with links ensuring they don't short to the ground trace below? I note that 'L' for component shorthand often indicated an inductor. Does this apply to Atari?
"Lxxx" just before an external port ought to be "T filters", an "EMI LCL Filter", at least, this is mentionned on the STe schematics.

T_filter_mention_ste_original.png
T_filter_mention_ste_original.png (45.03 KiB) Viewed 1218 times

On my conversion into Kicad, I used the dedicated symbol :

T_filter_kicad.png
T_filter_kicad.png (32.46 KiB) Viewed 1218 times
BigSteve
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Re: Zero ohm resistors?

Post by BigSteve »

Awesome - that makes life easy - thanks for quick response to all who replied. This looks to be a great forum!

:D
Maximilian
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Re: Zero ohm resistors?

Post by Maximilian »

In some cases I have seen a 0 ohm resistor being used as a sort of fuse, and in those cases I have seen these fail.

But seeing the previous responces it is not likely in an Atari.
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Re: Zero ohm resistors?

Post by terriblefire »

A 0 ohm resistor can also be used to add a pseduo extra layer for those one or two signals you need to route over each other. Used mostly on single sided PCBs etc.
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Re: Zero ohm resistors?

Post by rubber_jonnie »

Atari do tend to use links or zero ohm resistors in a few places. Look at the STE board for example. The TOS ROM Jumpers, W102, W103 & W104.

These are usually linked with the same zero ohm resistors.

As long as you're sure any replacement doesn't cause a short, a simple wire link is just the same, at least in the case of the ST.
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