The Defpom Forum, for RadioMods, S&M Software and Music by The Defpom

I just picked up a Cobra 29 NH ST off eBay... it?s seen its better days; i plan on uising it for a platform for a custom radio.

It came with the drivers missing and looks like some one tried to install a swing kit and cooked the rings off the board where jp was soldered...

The 50/50/sw pot for the Vol and Sq has been removed from the radio...

I have some pots and a few other parts on the way.
I cannot seam to find a service manual any place on the net for this radio the board number is KEPC-255-C1.

The one thing I am worried about is there is a small black component that was on the solder side of the board, from what I can tell it was soldered across 2 disc if you have the radio open solder side up with the bezel facing you. The unidentified component would be about 1.5 inch or so more to the rear of the radio than the (D2816C) IC.

The unidentified component was cracked... i would like to get it replaced before i try to power up the rig.

So I guess what I am looking for is any service information any one may have on this radio, or any input you may have on what this unidentified component may be.

Thanks for any help any one gives

KW

I do not know the Cobra model 29 NH ST; do you mean 29 NW ST?
You may well get a schematic diagram from Cobra just send them an email requesting the diagram with the model number and PCB number. The email address you need is parts@cobra.com they are not very fast at replying. If you have no look with Cobra, then let us know where the broken component go to and from not just where it is on the board.

The model is cobra 29 NH ST

its the Night Hawk with Sound Tracker. there is plastic rings around the knobs that glow.. not the EL face.

i will take some pix and post them some time today..

i listed the location of the component as there is verry few parts on the solder side of the board.. i looks like a SMT resistor or maby a diode.

any who.. i just ziped off an email to cobra for the service manual.

Ok the Green Rings are the component i am trying to find out what it is.

The yellow rings are one just like it but also dont know what it is..

the red line is the two solder pads where it connected.

A Few more shots

Ok

After looking at this all day trying to make heads or tales of it this is what i got..

the SMT chip above is D13, instead of putting in a normal axial diode they use a SMT diode and just poped it on the pcb side of the board..

the other smt chip I was talking about is d16, looks like cobra did the same thing they put a SMT diode in place of the axial.


My BOM does not have D13 or D16 listed if any one knows what values are supposed to be please let me know thanks.

D13 is SVC251 Varacap and is connected from the junction of R89 and C89 to Ground. D16 is SVC251 varacap and is connected from the junction of X1 Xtel and C131 to Ground.

Ok so this is a Voltage Variable Capacitance Diode, must be used to keep the radio from drifting, RIGHT?

i looked up the number on mouser and digikey and also googled it.. cant seam to fine a Brand name part.

how do you feel about the Radial mount ECG replacement part NTE614. for the most part i try to stay away from ECG.

D13 is the VCO Varacap and D16 is the Voice lock Varacap. I do not know about ECG devices, No info in the UK. The sub you can you are BB148, BB909A or B and KDV251 or you could try any out of a scrap radio. Digikey have the BB148 in stock.