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Author Topic: Icom techincal (component) question  (Read 931 times)
W7EJT
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Posts: 142




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« on: May 05, 2013, 01:44:42 PM »

IC-735 Main board:

I found a broken "jumper". In the service manual it is called W27

What is mysterious to me is - the "jumper" (there are lots of these on the boards) is an all- white device about the size of a 1/4 watt resisitor? I measured several of these and they are indeed "jumpers" with zero resistance in both directions (not a diode, etc).

My question is - why would Icom use these white (resistor looking) devices instead of a piece of wire?

Appreciate any comment...
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W6EM
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Posts: 901




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« Reply #1 on: May 05, 2013, 02:04:14 PM »

IC-735 Main board:

I found a broken "jumper". In the service manual it is called W27

What is mysterious to me is - the "jumper" (there are lots of these on the boards) is an all- white device about the size of a 1/4 watt resisitor? I measured several of these and they are indeed "jumpers" with zero resistance in both directions (not a diode, etc).

My question is - why would Icom use these white (resistor looking) devices instead of a piece of wire?

Appreciate any comment...

Could be that when they manufactured the radio, their "board stuffing" equipment stuffed components more precisely than wires used as jumpers.  Assuming, that the white jumpers were truely zero ohm resistors.


It is not at all uncommon to see "0" marked chip resistors,, that were destined to be jumpers.  SMT board gear appparenetly stuffs them just fine....

Lee
W6EM
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WB6BYU
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« Reply #2 on: May 05, 2013, 02:28:09 PM »

Yes, I have found a number of them in both white and yellow, basically just a bead of
insulation around a wire.  Those work better in the automated "pick and place" assembly
machines than a simple piece of wire with normal insulation because they are sized to
match other components that are already being placed on the board.

Feel free to replace it with a piece of wire.
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W7EJT
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Posts: 142




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« Reply #3 on: May 05, 2013, 04:10:08 PM »

Sort of what I was thinking. Easier for Icom to assemble the radio (manufacturing process).

Thanks for the inputs.

I'm going with wire!!!

Thanks again

Alan
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K2GWK
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Posts: 534


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« Reply #4 on: May 09, 2013, 09:52:51 AM »

The manufacture of these circuit cards is automated using pick and place machines. When programming the pick and place machine, the programmer simply programs another "resistor" for the jumper so no special handling is required with a piece of wire.
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Guy
Lawn Guyland, New York

K2GWK Website
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