Im messing with another Uniden PC 122 radio I have here. There was no audio to the speaker so I baught a new audio chip well that wasent it problem still exists . My question is if the large value coupling cap is bad I know itwont let audio to the speaker but will there be regular audio or modulation to the finals as this one is?? What is the propper way to test these caps for a short using a multimeter??? I have a Capcitor tester but dont know where it is at the moment or if its even for this type of use all I know is its a Beckman. I was also had read that another problem could be the squelch device a clamp transistor is connected to the audio chip and if bad wont let audio to the chip. where would this be??? The speaker is fin because the radio has been tested with an external speaker also. I know there was pa modulation also so with all that there isnt much more that could be wrong or could go wrong to create this problem Thanks Tony....
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Uniden PC 122 help needed
- Thread starter TonyV225
- Start date
Is this 1000mf 25v cap the one that would be the coupling cap theres 2 one by the transformer and one right infront og the ic chip they say its a large valued cap so im asuming its one of these and the one behind the transformer in the back right corner. And would radio shack carry these in stock???
T
The Defpom
Guest
The fact that the PA works tells me that the audio IC and large caps are OK, no RX audio is caused by a few things, but try checking parts, in the order I list them: C170, TR12, TR11.
If there is audio on SSB but not on AM I would suspect one of the AM detector / ANL diodes: D7, D8, D9.
If there is audio on SSB but not on AM I would suspect one of the AM detector / ANL diodes: D7, D8, D9.
Sometimes it feels as if IM going back into time around here ? I remember a post like this before , I too had a PC-122 that transmitted and received on AM/SSB just fine but the speaker on the radio /ex.speaker jack did not work (couldn't hear anything coming in) ,PA was just fine, but it did turn out to be 1 or 2 or both of the biggest caps in the radio , Why ? I do not know , It just worked the right way there after. I sat there for about 45 mintues with the tech that was trying to figure it out , changing this and that as he went along , finally one cap and then the other and the problem was solved. He really didn't understand it himself ? .....My wallet did though.
as afr as tesing these caps what is the best way to check them??/can i do it with a multi meter?? I do have a capacitor tester. I checked both big caps they are 1000uf 25v caps one tested at 1014 one at 1012 one was different than the other. I never used a capcitor tester till today i set it at 2000uf setting and thats the numbers i got does this sound right
does anyone have a schematic thats better than the one i have mines all blurry
i cant find c170 i found 171 169 and all surronding number but no c70. i also am looking for tr11 tr12. LOL This is frustrating. i qalked away several time s and came back but no luck. my guess is c170 is in the back left corner by the transformer I will prbally just replace the caps def suggested looking at
i cant find c170 i found 171 169 and all surronding number but no c70. i also am looking for tr11 tr12. LOL This is frustrating. i qalked away several time s and came back but no luck. my guess is c170 is in the back left corner by the transformer I will prbally just replace the caps def suggested looking at
Ok I was wondering as far as replacing these Caps can I use a 1000UF 35 Volt in place of the 1000UF 25Volt Caps it currently has?? Both of these pc122 have the 25 volt but if I remember right the Schematic link above shows 35 Volt anyways in it