Ok so radio is a connex 3300 zx dual final model with ept360014b board in it. Rx is just about totally gone. I can only hear a slight tone from 2040 sig gen turned all the way up. So I figured I would start to trace the the signal being injected from the antenna input over to tr17. Problem is there is no sign of signal on scope until I get to tr18. I'm confused because I thought I from looking at the schematic the signal has to go to tr17 rf amp first? So what's going on here? Any help is appreciated. I hope I explained it well enough.
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Connex 3300 rx help needed
- Thread starter Mk121
- Start date
Are you seeing IF image? TR18 if your 1st IF amp. So you may be injecting your RF signal thru your body capacitance...
Might need to do some voltage checks
Might need to do some voltage checks
Hmm.. Don't want you to tear apart a radio and replace bits of it one piece at a time...
But, if IC1 - if it's "not working" there are several "causes"
That 3300 if it's old, the 3600-14B board, they kinda did a "endless spiral" Nautilus maneuver -
They made the Detector section tight against the IF Strip towards the front - the IC1 to the back of the radio - and a river of pipelined communication signals from the Headers that go to the front of the board - as the blocking exit to the Audio Amp.
So they built a bridge and all the inherited fine-teeny-tiny little fine detail work that all it has to do, is to fish it out of that section in a way that although works, ahemn...not the most ideal. At least as far as China has dealt with it...The rest of us see the front headers to the front panel and back again, as the "bridge" that detected audio has needed to cross for years (decades - even)....
So that is where those issues with IC1 come into play. All that tiny detail work that is necessary.
So you'll need to go thru the checklist of - "If TR17 has 8V but this line doesn't - then go here, and check this, then... and do not pass Go and Do Not Collect $200 until you have it working - else customer won't pay...Scenario..
IC1 is the crux of all the communication needs for the main PCB, the PLL is the last but not least on the list. However. IC 1 calculates, S/RF meter - and AGC gain levels, as well as use and Set squelch levels all based upon the perceived notions that IC 1 - is a simple Quad Op amp chip-which has been delegated, like New York City's "Bradley Fighting Vehicles" - to the As-Long-As-I-Live duty of - Garbage Collection and Recycling..
Meaning:
IC 1 is labeled as such - because it handles all the necessary functions without complaining - even though you need PLL for your ability to change as well as use the channels. And yes, it will drift whether IC likes it or not - it's not its' problem - it's working the Bilge side of things...
So - did I forget to mention, if the radio is old - you have to recap this radio for the lines you use for RF Gain, use voltages from IC 1 shared amongst others - but if the radio has a cap that crapped out on you, then recapping starting along the lines of AGC and RF Gain and RX side of things with fresh Electrolytic capacitors in your only option.
Electrolytic cap design hasn't changed much - they still dry out and their plates are wrapped up tighter than John Denver's Rocky Mountain High - High - can short out and fail killing your receiver because they will appear as "Dead short" - similar to your results - that there is no voltage sourcing to the TR17 or any place else for that matter. If you're not careful - continued use of such radio will wind up possibly destroying it - part by part - as a cascade (not Mountain style but Avalanche is a working AdVerb here) event and cost $$$ to repair than simple recapping can do in prolonging the life and ability to keep it as stock as possible...
It's not a bad thing - just you have to go get new ones.
But, if IC1 - if it's "not working" there are several "causes"
That 3300 if it's old, the 3600-14B board, they kinda did a "endless spiral" Nautilus maneuver -
They made the Detector section tight against the IF Strip towards the front - the IC1 to the back of the radio - and a river of pipelined communication signals from the Headers that go to the front of the board - as the blocking exit to the Audio Amp.
So they built a bridge and all the inherited fine-teeny-tiny little fine detail work that all it has to do, is to fish it out of that section in a way that although works, ahemn...not the most ideal. At least as far as China has dealt with it...The rest of us see the front headers to the front panel and back again, as the "bridge" that detected audio has needed to cross for years (decades - even)....
So that is where those issues with IC1 come into play. All that tiny detail work that is necessary.
So you'll need to go thru the checklist of - "If TR17 has 8V but this line doesn't - then go here, and check this, then... and do not pass Go and Do Not Collect $200 until you have it working - else customer won't pay...Scenario..
IC1 is the crux of all the communication needs for the main PCB, the PLL is the last but not least on the list. However. IC 1 calculates, S/RF meter - and AGC gain levels, as well as use and Set squelch levels all based upon the perceived notions that IC 1 - is a simple Quad Op amp chip-which has been delegated, like New York City's "Bradley Fighting Vehicles" - to the As-Long-As-I-Live duty of - Garbage Collection and Recycling..
Meaning:
IC 1 is labeled as such - because it handles all the necessary functions without complaining - even though you need PLL for your ability to change as well as use the channels. And yes, it will drift whether IC likes it or not - it's not its' problem - it's working the Bilge side of things...
So - did I forget to mention, if the radio is old - you have to recap this radio for the lines you use for RF Gain, use voltages from IC 1 shared amongst others - but if the radio has a cap that crapped out on you, then recapping starting along the lines of AGC and RF Gain and RX side of things with fresh Electrolytic capacitors in your only option.
Electrolytic cap design hasn't changed much - they still dry out and their plates are wrapped up tighter than John Denver's Rocky Mountain High - High - can short out and fail killing your receiver because they will appear as "Dead short" - similar to your results - that there is no voltage sourcing to the TR17 or any place else for that matter. If you're not careful - continued use of such radio will wind up possibly destroying it - part by part - as a cascade (not Mountain style but Avalanche is a working AdVerb here) event and cost $$$ to repair than simple recapping can do in prolonging the life and ability to keep it as stock as possible...
It's not a bad thing - just you have to go get new ones.
Thanks for the reply Andy. I tried my best to follow along with what your saying. I will swap out the caps being that the radio is older and also has some 10v in it. I definitely think ic1 is what is causing the radio to act up. But what is causing ic1 to act up is the big question. Looks like I got some more work to do.
Just work in stages, don't make it harder than it is.
I rambled a bit to give you some humor if not just a process of thought as you work thru all of this.
You're on the right track, I don't want to see you get sidelined from a quirk that symptoms like TR17 and TR18 have shown you, one works but the other doesn't...why?...well - because one uses what IC1 looks for and sends back a signal to say "only so much" while the other, uses what the PLL has generated, and expects the other part to pass along a signal at a given level so it can mix (cook - boil down - image - generate - create - whatever) that to form a newer signal that the rest of the "What Happens IN The IF Strip - Stays IN The IF Strip" - Strip - can process and depending on where the knobs and switches get set to - either just plain old AM or something more fancy for Discriminating Tastes - like FM.
That's just for the two main modes - that board can handle even more modes than that - so the devil is in the details because the wrong part in the right spot, and - or, right part in the wrong spot - either way it will not work. Welcome of the "Galaxy-Class" the Cadillac of Chevrolets - you get a Basic Model (Transportation) and you go up in features you go up the chain of various accessories - but they all use nearly the same base structure - a hole is there for the mounting of the next level up parts.
That's why the "Nautilus" reference - a sea Barnacle (Mollusk) that is left in the dark a lot and feeds off the it's share of the food chain. Change the environment - the creature can't work - won't do it's share.
But it is also interesting to see the Fibonacci sequence or Golden spiral effect. That being, IC1's position in relation to the others - and how it plays a role in this.
I rambled a bit to give you some humor if not just a process of thought as you work thru all of this.
You're on the right track, I don't want to see you get sidelined from a quirk that symptoms like TR17 and TR18 have shown you, one works but the other doesn't...why?...well - because one uses what IC1 looks for and sends back a signal to say "only so much" while the other, uses what the PLL has generated, and expects the other part to pass along a signal at a given level so it can mix (cook - boil down - image - generate - create - whatever) that to form a newer signal that the rest of the "What Happens IN The IF Strip - Stays IN The IF Strip" - Strip - can process and depending on where the knobs and switches get set to - either just plain old AM or something more fancy for Discriminating Tastes - like FM.
That's just for the two main modes - that board can handle even more modes than that - so the devil is in the details because the wrong part in the right spot, and - or, right part in the wrong spot - either way it will not work. Welcome of the "Galaxy-Class" the Cadillac of Chevrolets - you get a Basic Model (Transportation) and you go up in features you go up the chain of various accessories - but they all use nearly the same base structure - a hole is there for the mounting of the next level up parts.
That's why the "Nautilus" reference - a sea Barnacle (Mollusk) that is left in the dark a lot and feeds off the it's share of the food chain. Change the environment - the creature can't work - won't do it's share.
But it is also interesting to see the Fibonacci sequence or Golden spiral effect. That being, IC1's position in relation to the others - and how it plays a role in this.
Ok so I might of stumbled upon something. I was verifying that my signal generator was still working. As I went to disconnect the coax from back of radio my receive came back. I noticed that if only the center pin is inserted and leave the collar unscrewed on the pl259 I have rx. So I'm guessing there is some kind of ground issue going on? Thoughts?
Ok if you look at the SO239 CHASSIS connector on the schems you can see there are only so many things that could cause that or be shorted. Unsolder anything connected to the SO and then test for a signal on the pin inside the radio. This may seem rudimentary but it takes the guesswork out of it.
Check the SO239 - might need a 19mm Wrench to tighten.
Also they did use several area where the "rivets" held the board to the rear panel and also provided RF and DC isolation from each other.
More than likely the issue is in and around the Coax Connector and SWR board (jumpered if not used) area - reflow some solder and check those board mounting areas.
Also they did use several area where the "rivets" held the board to the rear panel and also provided RF and DC isolation from each other.
More than likely the issue is in and around the Coax Connector and SWR board (jumpered if not used) area - reflow some solder and check those board mounting areas.
