RCI-2950: What does the VR -701 Pot do?

[Robb]

I just tuned up a RCI-2950 - non "DX" model.

I didn't see in the tune-up guide what the VR-701 pot does.
Has anyone come across this before?

Here is the page that shows it on CBTricks:
Ranger RCI-2950 Service Manual

 

[sp5it]

Probably it is used to adjust display contrast.
Mike

 

[Robb]

I appreciate that guess, sp5it.

But no one knows - eh?

Thought it might have been used to change the freq readout . . .

 

[wavrider]

Robb,

I viewed all the schematics and alignments can not find anything associated with that VR.

Perhaps give a Ranger service center a phone call and ask them.

 

[Wire Weasel]

I think sp5it has it. It's right on the display. About all it can be is the contrast or maybe adjusts the brightness of the LED's for one or all of the dimmer settings.

 

[unit_399]

Robb -

VR701 is connected across pins 16 and 17 of the HD61602 display driver IC. Pin 16 outputs a voltage (Vref1) and feeds it through VR701 and back into input pin 17 (Vref2). The resistor is adjusted so that Vref2 is the correct driving voltage for the particular type of LCD display used. This voltage (V1) outputs on pin20, is bypassed with a small cap, and goes to the display. VR701 doesn't have to be readjusted unless the display itself is changed.

- 399

 

[SLUGGO_]

If somebody messed with this pot would it screw up the display.

 

[unit_399]

Probably would.

- 399