Remove Pull-Up Resistor from Expansion Board

BraveSirRobbin

Moderator
I need to remove the pullup resistor from the last zone of an Elk M1 Zone Expander. I think I have the correct surface mount resistor circled in red in the attached pic.

Can I have a rep from Elk verify this is the correct component?

Thanks,

BSR
 

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znelbok

Active Member
Can it then be assumed that removal of any resistor that is Z#+5 = resistor number(eg for zone 1, remove R6) will do the same for that zone

Mick
 

znelbok

Active Member
All sixteen basically. As I add more devices I will need to use a new zone, so understanding that up front helps.

But to start with, Z1 through to Z6.

At a guess (from my version of the board)

Z1 - R4
Z2 - R18
Z3 - R19
Z4 - R20
Z5 - R26
Z6 - R27
Z7 - R28
Z8 - R25
Z9 - R26
Z10 - R32
Z11 - R31
Z12 - R30
Z13 - R24
Z14 - R23
Z15 - R22
Z16 - R21

Also - the picture of the input expander is different to the one I have. The location of the resistors looks different

The sticker on the back has M1XIN/PC097R.E QEMS4706.

I am assuming that the PCB has undergone some revisions since the original picture was posted.

Mick
 

jrobinsonii

New Member
Not to bring up an old post, but could anyone post a quick how-to on removing the pull-up resistor from the expansion board? Does anything need to be put in place of the removed resistor?

Thanks!
 

znelbok

Active Member
I used a small propane soldering iron. Gives a very fine point of heat. Not too much so that you melt everything.

Just heat the reistor up, pull it off and thats it. Nothing needs to go in place of it.

Mick
 

BraveSirRobbin

Moderator
JOOC why would someone need to do this?

When using the Elk inputs for analog measurements, the built in 'pull-up' resistor can seriously influence small current drive capable voltage measurements. By removing the pull up resistor, one would get a true reading from this voltage source as it now doesn't have to 'overcome' that resistor. Of course, you still get only eight bit resolution (for more info on that see my Analog to Digital Converters Explained Guide).

Also, I believe you still have an 'update' issue on the zones themselves, especially on an expansion card.
 

fcwilt

Active Member
When using the Elk inputs for analog measurements, the built in 'pull-up' resistor can seriously influence small current drive capable voltage measurements. By removing the pull up resistor, one would get a true reading from this voltage source as it now doesn't have to 'overcome' that resistor. Of course, you still get only eight bit resolution (for more info on that see my Analog to Digital Converters Explained Guide).

Also, I believe you still have an 'update' issue on the zones themselves, especially on an expansion card.

I wasn't aware that the Elk inputs were designed to support analog measurements - or is this just a hack?
 

BraveSirRobbin

Moderator
I wasn't aware that the Elk inputs were designed to support analog measurements - or is this just a hack?

Well "designed" may be a stretch; but, yes the Elk can support analog inputs with the known limitations described above and in other posts here! It is a 'type' listed on an input zone.
 

jrobinsonii

New Member
I used a small propane soldering iron. Gives a very fine point of heat. Not too much so that you melt everything.

Just heat the reistor up, pull it off and thats it. Nothing needs to go in place of it.

Mick


Thanks, Mick. I figured that was the case, but I just wanted to be sure.

- John
 
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