Cobra 29 ST LTD Off Freq

[RedEye]

I have a Cobra 29 ST LTD that is off freq, I noticed by comparison of another unit that there is a small black surface mount on the solder side of L24. by the crystal. It is cracked/half missing on the one that is off freq. Does anyone know if this is a resistor/cap? and what the value is?
I am hoping this is all it is.

Thanks in advance!

[Rick]

C511 is 47p this is between PLL pin 19 and the xatl and ground. C512 is 39p this is between PLL pin 20 and the xatl and ground and CT500 trimmer is 2p to 22p this also between PLL pin 20 and the xatl and ground.

[RedEye]

Thanks Rick, I had to play with it for awhile to find the value, But I centered L24 and tried small value caps and went up, 27p put it at 27.183 and I ajusted the rest with L24. (chan 19, all other channels are ok too.)

I noticed I can play with the value and drop it 10kc's would this be a viable way to make a 10kc slide on a 29? (through a on/off switch - correct cap value in off position and new value in the on?) or is there a better safer way?

One side effect, may not be related, I have to look still, but the unclocked Clarifer (delta tune) does not adjust now...

I used plain ceramic caps, do I need electrolitic caps?
Thanks again for all your help.

[Rick]

I do not know which 29 LTD ST you have, as my diagram does not show L24.
What is the PCB No? and CPU No?

As for switching in some a cap, you cannot do this with wiring and switch alone as you have RF floating around this will have the radio putting out all sorts of spogs. You need to a transistor or diode to switch in the extra cap (See diagram) the resistor 5K6 to 10K will do.

[RedEye]

Attached are top/bottom photo's
1997 China made sound tracker
The bottom picture shows where the small black surface mount is missing, jumped by a ceramic cap. all works well except no clarifier(delta tune) change on rx/tx...slide mod was done, cut r112,d18, jump r110, move orange wire to 8volt....

[Rick]

I gave you the wrong circuit ref and values I assumed you had a late 29 LTD ST as you talk about SMT I forget about the 29 built around 1997 to 1999 as this model was not very good and must used as a door stop. This is why it is all ways best to give the PCB No and PLL or CPU No this makes it easier for some one to help you.

The SMT cap which broken is C131 10pF this is in parallel with the varcap D16.

As for the Delta Tune what are you hoping to achieve by unlock it?

[RedEye]

I used a 7pf and adjusted it back to freq. Radio works good now, The delta tune was modded already, I put it back to stock, but it still dosen't shift RX, no big deal though, it is on freq.

I know many do this mod but I am unsure why as you are... I guess it makes em feel good just to be able to.....
Thanks again for your help. I have become the "tech" or "low tech" might be better... heh heh ...around here for alot of the Sand mine truckers in the area. There aren't any techs in the area, just hacks who cut limiters and spread coils... Everyone on the forum (especially Rick) have been a great help and lots of people appreciate it here in Florida!!!!

Het Rick, have you started a Peltier project yet? Let me know if you want some used ones, I can pick em up and probably ship em from here pretty cheap....