Lincoln Missing Connection?

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Rob_RS2000
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Lincoln Missing Connection?

Post by Rob_RS2000 »

Does anyone know where the orange wire should be connected, i've looked at every online image that i can find and drawn a blank (I can't work it out from the circuit diagram either)
20170127_145053.jpg
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Re: Lincoln Missing Connection?

Post by Otter »

Um, which orange wire exactly?
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Re: Lincoln Missing Connection?

Post by WeatherWatcher »

Had job to see your highlighted one - only visible when pic enlarged- hope someone can help you.
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Re: Lincoln Missing Connection?

Post by 14CS06 »

Hello

the orange wire is connected on J 302

Image

Image

Image

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Re: Lincoln Missing Connection?

Post by Rob_RS2000 »

Otter wrote:Um, which orange wire exactly?
Sorry, highlighting is not clear, if you look at the enlarged image, its the one circled in red on the 4 pin connector just left of the FM PCB.
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Re: Lincoln Missing Connection?

Post by Rob_RS2000 »

Claude,

Thanks for that I think it's the first time I've seen a diagram that details the wiring, I should be able to work it out from this.

Edited to say:

Just had a look and I am guessing that this is part of a "mod". it looks just long enough to reach the orange one that is shrink sleeved with red wire.



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Re: Lincoln Missing Connection?

Post by Rob_RS2000 »

Ok, think I am getting somewhere now, looks like this is a RIT mod.

Also looks like it's had an anti-talkback mod done, at the moment I have no RX audio and radio will not go into TX mode, so will start looking into this mod as it could be whats causing the problem.
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Re: Lincoln Missing Connection?

Post by 14CS06 »

Hello

J 302 the orange wire is N° 8

Image

CONNECTOR ON PCB

Image



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Re: Lincoln Missing Connection?

Post by Admiral »

Rob_RS2000 wrote:Ok, think I am getting somewhere now, looks like this is a RIT mod.

Also looks like it's had an anti-talkback mod done, at the moment I have no RX audio and radio will not go into TX mode, so will start looking into this mod as it could be whats causing the problem.
You have no RX and no TX? Sounds like the processor is fried my friend.
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Re: Lincoln Missing Connection?

Post by Rob_RS2000 »

[/quote]
You have no RX and no TX? Sounds like the processor is fried my friend.[/quote]

I have a rudimentary understanding of microprocessors, and can confirm to the best of my knowledge that my processor is operating correctly. So find it hard to understand how no RX and no TX = faulty processor. ;)
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Re: Lincoln Missing Connection?

Post by dt307 »

Didn't want to chime in as some one else was helping .

First get the service manual and go through it
If the vco has died shorted cap or missing frequencies this will show up.
Also check for 5v on the ptt line of the mic socket. There are diodes and switching transistors on the rx tx lines.
Is there any indication on the display that it's switching between rx and tx
There is a million probs that maybe
There are small coax cables on the cpu board make sure they are seated properly both ends

It's hard when a radio ain't in front of you to give advise unless a common problem

Could well be the cpu is playing up as been said

But if you go through the service manual step by step I think you will find some test you can't do because a frequency is missing or a voltage is way out due to a component pulling the voltage down .. Or send it to some one that take a look for you.there is many probs with this chassis caps and glue eating tracks on cpu board ect
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Re: Lincoln Missing Connection?

Post by Admiral »

Is C60 going open circuit the Google favourite for this issue?
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Re: Lincoln Missing Connection?

Post by dt307 »

Admiral wrote:Is C60 going open circuit the Google favourite for this issue?
had a quick look at that and dont think it would but i think you mean shorted m8?

if it was shorted then yes it could pull the line down to deck and all the voltages will be out on the op amp (ic104)
gotta love the little demon ticking time bomb caps
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Re: Lincoln Missing Connection?

Post by Admiral »

dt307 wrote:i think you mean shorted m8?
Isn't that the same thing but different words?
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Re: Lincoln Missing Connection?

Post by Rob_RS2000 »

Thanks for all the help guys, I am getting somewhere slowly. CPU/PLL should not be a problem I am not using the standard CPU have installed and programmed a PIC and I am getting all the correct frequencies at test points on the PLL board.

I am currently focusing on the receive issue, there is white noise but very low and is not effected by the vol control. From the service manual I see that i am getting no voltage at Q135 (AF Amp) if I probe the collector of this transistor I get a loud buzz so looks like the audio amp is working. I have already removed an old mod that was stopping Q109 from switching on squelch. I am now changing out caps around Q135 to try and figure out what is wrong here.

I am also not able to get a frequency reading at the 10.695 Xtal but not sure if my frequency counter is up to the job, manual says TP1 but this is not labeled on the PCB (think its a very old one).

Just to note: All voltage are correct at IC104

Edited to add:
Just noticed that L203 on NB board has it's core missing, not sure where I can get a replacement, is it possible to bypass the Noise Blanker?
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