Ranger rci-2950cd help to clean up

[Eldorado828]

I acquired a slightly worn 2950cd from a driver for 50 bucks and just couldn't resist.

So it works, is relatively close to being on frequency and it's loud..... too loud, like golden screwdrivered nasty loud.

I can't find a current schemo so I'm winging it to try and clean it up.

Foil side of the board looks like a swing mod coming off of the regulator as shown here. It will be removed.


Now on the other side is where I'm in question.
Comparing this to my already owned 2950dx6, R302 is absent from the factory.

But.... next to R302 are another set of pads missingthe resistor.
Shown here with the red arrow


Is this a part of the limiter circuit? If so does it affect AM and SSB?

 

[nomadradio]

Not sure what a 2950 Cee-Dee is. Looks like the "DX" model, with the EPT695015Z circuit board. R302 has something to do with setting power level in CW mode. Pretty sure the factory just left it off.

The schemo for the DX radio made after 2006 or so is here.

https://cbtricks.org/radios/rci/rci_2950dx/graphics/rci2950dx_ept695015z_mosfet_sch.pdf

Did you try turning down the AM modulation with VR17? The picture shows the modulation-limiting transistor Q43 appears unmolested. That's the one they will pop that makes it sound nasty. I worry more about the sideband ALC. It it's wide open the finals can easily overheat and fail from the overload.

73

 

[Eldorado828]

Thanks for the reply @nomadradio .

I'll definitely visit the ssb alc but I'm trying to straighten out the added and removed components first. I looked at the schemo but I'll have to trace it out on the board because that particular set of pads isn't labeled. Not sure which resistor that even is so I can repopulate the pads with the correct value.

I figured I'd throw it out here to see if you experienced techs could help point me in the what it is and why. I was speculating that it's part of the limiter circuit but I may be way off. I'll probe around and find out.

 

[Eldorado828]

Well the schemo wasn't matching up for a reason and it's because the silk screening on the board has some incorrect printing on it.

The R302 isn't correct and shouldn't even be there so it threw me way off. That resistor is actually R203 instead so that means the missing resistor is R201 which is a 5.6K ohm.

Now I'll revisit the schemo tomorrow to see how that changes things.

 

[nomadradio]

the board has some incorrect printing on it.

Wouldn't be the first time.

73

 

[9C1Driver]

Not sure what a 2950 Cee-Dee is. Looks like the "DX" model, with the EPT695015Z circuit board. R302 has something to do with setting power level in CW mode. Pretty sure the factory just left it off.

The schemo for the DX radio made after 2006 or so is here.

https://cbtricks.org/radios/rci/rci_2950dx/graphics/rci2950dx_ept695015z_mosfet_sch.pdf

Did you try turning down the AM modulation with VR17? The picture shows the modulation-limiting transistor Q43 appears unmolested. That's the one they will pop that makes it sound nasty. I worry more about the sideband ALC. It it's wide open the finals can easily overheat and fail from the overload.

73

The RCI 2950 DX cd stood for color display. They have been discontinued.

https://www.walcottradio.com/ranger-rci2950dxcd-1012-meter-radio-with-modes-amfmusblsbcw-p-3093.html?srsltid=AfmBOopGPJZg6j4mI_9kRh-jxF7jhHk1Kc710amjhx1XI1N7YmKai51J

 

[Eldorado828]

The RCI 2950 DX cd stood for color display. They have been discontinued.

https://www.walcottradio.com/ranger-rci2950dxcd-1012-meter-radio-with-modes-amfmusblsbcw-p-3093.html?srsltid=AfmBOopGPJZg6j4mI_9kRh-jxF7jhHk1Kc710amjhx1XI1N7YmKai51J

Yes sir, you are correct. It was replaced by the 2950dx6 with the slightly different final section.

I haven't continued on with this project but as @nomadradio suggested, ssb alc was cranked wide open.

My suspicion on the missing resistor is that it is a part of the limiter because of its proximity to the audio section and because it swings wildly like it should not. If it affects Am and or ssb is to be determined once I can study that schematic.

More to come

 

[RicochetRabbit]

that resistor R201 is a 562 /R67,94,201,290,291 RCY015624Z 5.6KW 0.1W R302 is empty