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TRC-421A schematic anyone ?

Sam's

Well i see this listed ..

TRC-421 (21-1536)..................273

Wonder how different the 421 and 421A are
Anyone's got the 421 then ?

ps got the full lc7131 Sanyo data sheet. I checked it's operation earlier on , the chip seems to react correctly , i see the keying , switch for channels are ok i see it go hi lo changing channel switch setting pins 1 to 5 .. but at the VCO out pin 17 i got 6.3 some volt stable and no change when i change channels .. the VCO seems simply dead . i hear my generator set to 455khz modulated through the speaker . rf section is ok so are all the if's
so my big guess is that the VCO somehow is dead .would explain why tx and rx are dead .. injecting a signal to the tx chain gives an output on the rf jack .. ill keep checking in that area pulling silicon as needed. Anyways .. back to the lab in the morning.
 
Check out the TRC-422A schematic. It's got the same PLL chip. Check it against your board. I have this radio as well. A NOS/NIB Ebay acquisition I have in addition to my TRC-421A
http://www.cbtricks.com/radios/realistic/trc_422a/graphics/trc_422a_sch.pdf
It's got the same tune points that Audioshockwave posted.
http://www.worldwidedx.com/cb-radio-modifications/114277-realistic-radio-adjustments.html
http://www.pedrokv.com/radio/navody/cbpllmod.html
For a more sensitive voice response view the link below. Notice that the 421A&422A are mostly the same :
http://kg4zpn.netai.net/cb/talkpower.htm
 
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at least really close

The schematic for the 422A is truly really close to what i got under my eyes.
chip nummers vary but i need to check the change between a 7130 and a 7131 but i believe it's close enough to allow me to get the job done.
At least layout is truly really similar.
It's helping a LOT Thank you .
 
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The schematic for the 422A is truly really close to what i got under my eyes.
chip nummers vary but i need to check the change between a 7130 and a 7131 but i believe it's close enough to allow me to get the job done.
At least layout is truly really similar.
It's helping a LOT Thank you .

The 7131 according to one of these links is modifiable but the 7130 isn't. Don't know what they mean by modifiable. Please post your progress on your 421a
 

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I got my Sams Photofact on the TRC-422. It is a different beast from the 422A in some areas. A different PCB. It has a 54mhz min. pot,IF AGC pot,and a T9 pot. The 422 also has a different PLL.
K86169
D2814C

IC1;UPD2814C HD42853,mfgr part #MX3540
 

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