W4 ignition jumper?

[mancow]

I'm looking for a jumper in a W4 head that eliminates the need for an ignition sense wire. I want it to simply power up with the use of the front panel switch.


Anyone know where these jumpers are and which ones to close or open?

[techie]

Why not just wire ignition to B+?

The manual lists JU1 and JU2.
The radio is shipped with JU1 out, and JU2 in.
for ignition control, wire ignition to switched B+.
for front panel control, wire ignition to unswitched B+
for ignition control of TX-inhibit, remove JU2, install JU1, wire ignition to switched B+, and enable TX-Inhibit in RSS.

[dxon2m]

On a similar note (I guess), what is the difference between switched and unswitched B+? I am planning to put a A4 spectra in my car and would like to just use the power cable (red+black) to power up.

Thanks

[mancow]

Thanks..................

[techie]

Looking at the schematic again, it looks like if JU1 and JU2 are both installed, then IGN and B+ are tied together, which
would probably accomplish what you are looking for. I would make sure to isolate the IGN lead.

If you're using a remote mount, then you already have a power lead to the control head, so I would just tie them
together, and not modify the head.
If you're using a dashmount, then it might be worth while.

I also noticed JU20, which bypasses the power switch when installed.

JU1 is in the middle of the board, above P103 pin 4. there is a resistor R177 perpendicular to the long side, then above that, JU1 parallel to the long side. the pin numbers of P103 run R->L->down->L->R. pin 26 is shown as missing.

JU2 is on the lower left, just above and to the left of pin 1 of the display. display pins are L->R.
JU2 is perpendicular to the long side, parallel to, and just to the right of R111.

The manual is available as a PDF on businessonline.motorola.com.

[techie]

On a similar note (I guess), what is the difference between switched and unswitched B+? I am planning to put a A4 spectra in my car and would like to just use the power cable (red+black) to power up.

Thanks

unswitched B+ is always hot, direct to the battery. It serves to keep memories, user scanlists, etc alive.
switched B+ is controlled by the vehicle ignition switch, and is used to turn the radio on/off with the ignition, or
to inhibit transmit (depending on jumper settings) if the vehicle is not on. It's intended to keep from running the
vehicle battery down if you forget to turn off the radio.

[Conundrum]

Thanks for posting this information,

I was just looking for this a while ago, and couldn't find an answer, Just finished modding my W4 head.