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Cobra 25ltd pll part # needed

BTW - it is the NPC "that makes it" but it's SM5126BP - see if you can find one like that...

Else ...
It may be what I feared, the BCD programming is different - you'll always see a correctly displayed channel, because it uses a different set of "tines" on dual-sided wafers that set channel programming on one side of the wafer and the other side simply shows the channel the rear part of those same wafers is programmed for.

So in some PLL service manuals - a "truth table" is used to show how the binary programming is used

If we only had one for the Cobra we may be able to find the PLL swap that will work
 
Thanks Andy i will post if I do find a replacement. Someone on ebay is selling the SM5126BP made by NPC. I dont think it will work but gonna buy one. Will post if it does.
Someone out there has to of replaced one of the newer dated 25ltd plls.
If no replacement it makes these radios throwaways. I wonder if cobra sells these chips?
 
Well, they MAY have at one time. Something tells me though that they are "Cutting ties" with a lot of their original suppliers and going strictly inhouse - meaning a lot of their sourcing for parts is thru small companies under a bigger umbrella of the corporation - looks like KEPC / KEIC and KEC are pretty much what Cobras' main sourcing is for now.

That kinda sucks because it now puts the Cobra line of CB radios from their golden days in jeopardy of becoming extinct due to lack of support.

Like FORD announcing what we've known for years, they're moving a lot of manufacturing overseas - Great! Doesn't lower the price of the car, just makes it cheaper to build so they make more money for what less we get in the same purchase price in return.
 

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There are quite a few cb radios using this newer pll so i'm surprised no one has figured a replacement for them. Oh well just ordered 1- 5126 coming from Cal. I'm in Boston so will have next week. $9.00 includes shipping
 
If you think that's bad, oh just wait until you get your hands on a new Cobra 29 - might as well throw the old service manual away - whole different ballgame when it comes to the PLL.
 
Making cb radios today like the vcr's were all made back when throw-aways if it breaks. And I know all surface mount parts
 
I'm sure that is for the earlier 25ltds like in the lat 90's the pll's i'm looking for are for the years 2006-2013 mfg date
 
But, if they had the cross reference for the newer replacement...is what I'm wondering - it's a call on a 1-800 number so they only thing it's gonna' bother is their staff....
 
Monday I'm going to call them and see if they will spill the beans and give me a replacement # LOL I'll threaten them and tell them I will never buy their cb radios ever again LOL
 
TC9106 and SM5126 are both directly controlled by the same programming lines that drive the LED channel display. Not BCD like a uPD2816 or binary like an MB8719 or MC145106. This saved them from using an extra channel selector wafer to program the PLL separately from the display. Any invalid LED display code that the ROM code in the PLL "sees" will cause it to not function.

With the PLL out of circuit and desoldered from the board, does the LED channel display function correctly in all of the channel positions? Assuming the LED is functioning and no burned out segments.

If the channel display functions wrong, in any position, then the channel selector switch is bad or dirty, oxidized, needs replaced or taken apart and cleaned.
If the LED display functions correctly in all of the channel positions, and you put the PLL (socketed) back in, if the LED was working without the chip, and now displays weird, one or more of the programming lines in the PLL may be shorted.

According to http://www.radiomods.co.nz/integratedcircuits/pllpinoutspage.html, SM5126A or B has the same pinout as the TC9106.
 
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NZ8N

thanks for the reply.

It was definitely the pll as I was able to buy 2 new ones and now the radio works good.
They are $20.00 apiece and needed to know if it was the pll. Crazy uniden does not mark a part # on the pll so you cant tell what chip it may be other than in my first post a picture of the pll.
 
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Yes Handy Andy still pissed there is no part # other than the picture in my first post. I know its a cheap radio but was curious if it was a pll so I had to buy one to see if that was the problem.
 
dss56 said:
Yes Handy Andy still pissed there is no part # other than the picture in my first post. I know its a cheap radio but was curious if it was a pll so I had to buy one to see if that was the problem.
Click to expand...

I know this is kind of an old post, but I have a china cobra 25 that is not receiving or transmitting. I have used a PLL voltage chart from cb tricks and find the voltages to be off. I was wondering how you came to find the PLL was bad, and where you got the replacement PLL, the ones marked Cobra?

cobra25pll.jpg

These are the voltages I have. The accented ones are inconsistent with the chart.
_voltages.jpg

Thanks
 

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