System Blue connector S1 3-4 ?

[elythomaslumber]

Hi!

running my System Blue for first experiments and set-up tests, waiting for my GPS antenna.

One question about the on-board connector S1 on PCB 19.3. By default 1-2 and 5-6 are jumpered but what about 3-4?
The schematic is telling me that a lot of IC's are connected to VDD but a jumper is needed on 3-4.

Obviously VDD is connected to the IC's since they are working. Is there any change in the PCB connecting them to VDD without the jumper or is there any further meaning for this jumper?

[kevinmcc]

Jumpers 1-2 and 3-4 provide voltage for the E-Input.

Jumper 1-2 is for sending 5v and jumper 3-4 is for sending 3.3v VDD.

VDD actually comes from the voltage regulator IC501.

Should leave those jumpers as configured.

Jumper 5-6 is removable if you want to add an optional on/off switch.

[piepants]

This is how I understand it too. Definitely do not jumper both 1-2 and 3-4, or you'll short the 5v input to the VDD output of IC501 and possibly damage ICs connected to VDD. I'm just guessing, but 5v is probably used on the E-field to counter voltage drop across the coax.

[elythomaslumber]

This is how I understand it too. Definitely do not jumper both 1-2 and 3-4, or you'll short the 5v input to the VDD output of IC501 and possibly damage ICs connected to VDD. I'm just guessing, but 5v is probably used on the E-field to counter voltage drop across the coax.

Thanks a lot! If it really can destroy the IC´s there should be some warning information added to the manual.

[cutty]

This is how I understand it too. Definitely do not jumper both 1-2 and 3-4, or you'll short the 5v input to the VDD output of IC501 and possibly damage ICs connected to VDD. I'm just guessing, but 5v is probably used on the E-field to counter voltage drop across the coax.

Thanks a lot! If it really can destroy the IC´s there should be some warning information added to the manual.

For Current release control boards, NO JUMPER on 3-4. The assembly instructions mention 2 jumpers, not three. You'd have to use 3 jumpers to accomplish this. or install the switch, and inadvertently use 3-4 as 'storage' for the removed 5-6 jumper.

Moving the jumper from 1-2 to 3-4 simply powers the E preamp with 3..3VDD instead of the 5 volts main. The newer E preamps want 5 Volts, so leave 1-2 as configured. 

I have early release with different S1 configuration allowing preamp to run with either voltage. That configuration made this situation you describe 'impossible', but created other possibilities for 'inattention' errors... which still exist in a couple of combinations of 'jumper' diddling...
Therefore I can't physically check and see if pin 3 is even connected to anything on the newer boards... someone might do so.
If it is in fact 'open'  (no connection to VDD) there is no danger of this happening.
For sure, suggest clarifying in documentation! 

Somebody is sure to do some inappropriate variation of these jumpers! 

[kevinmcc]

If you look at the board layout in the compendium, pin 3 is connected to a trace on bottom of board that connects to the VDD side of C402.

[Tobi]

Somebody is sure to do some inappropriate variation of these jumpers! 

That's true, I don't even know why we have so much jumpers there...