OK so I have a Uniden Washington PC 385AH board. The radio transmits but there is no receive I have static and I have tried an alignment but still no receive. I change Caps To 50v And also change TR five, TR six, TR eight , TR nine, TR 10. I also have no receive movement on the signal meter. Thanks in advance for any help
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Uniden Washington no Rx
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OK, Can you see a RED TX light when you key the radio into a 50Ω dummy load? Not just the S/RF meter up and down on the face.
Do you get a Green RX light?
Check squelch - hear a pop when it engage and disengage it?
Else no receive? It may mean some work, but simply replacing transistors is not the best approach, just a simple transistor check of the part and soldering it back in might be a chore but save the fresh parts for the ones you need to replace for the ones that don't work anymore.
This may mean a simple CB/PA switch check or even see if the PA function can still work, might have to replace some caps in the audio section - they usually dry out from age. So, look for fresh work - soldering that is different in small sections that looks different from the rest of the soldering job OEM-wise that wasn't or hasn't been messed with.
Do you get a Green RX light?
Check squelch - hear a pop when it engage and disengage it?
Else no receive? It may mean some work, but simply replacing transistors is not the best approach, just a simple transistor check of the part and soldering it back in might be a chore but save the fresh parts for the ones you need to replace for the ones that don't work anymore.
This may mean a simple CB/PA switch check or even see if the PA function can still work, might have to replace some caps in the audio section - they usually dry out from age. So, look for fresh work - soldering that is different in small sections that looks different from the rest of the soldering job OEM-wise that wasn't or hasn't been messed with.
I have a green light on receive and a and a red light on transmit very small amount of RF coming in speaker even if I plug in a external speaker same problem.Pa work and transmitter works just very small amount of noise in speaker but it doesn’t receive the radio that’s next to it on the same channel
Check your Squelch operation - when you have the other radio keying up next to it - observe the operation of the squelch.
Squelch is 1/2 way between the "detected" AGC'd and onto the Volume - section of the radio - kind of important section to know how the SQ is working and how well it can detect the weak signal and operate the control using the background and the Signal ratio and open and operate just above a noise level.
If the Squelch seems to operate as if it's detecting the signal above the noise floor the radio has - meaning you can set the sq control to quiet the static, then when the radio keys next to it - it senses this and opens and closes when it unkeys - this is a critical stage of operation - which helps you determine the area affected.
Squelch is 1/2 way between the "detected" AGC'd and onto the Volume - section of the radio - kind of important section to know how the SQ is working and how well it can detect the weak signal and operate the control using the background and the Signal ratio and open and operate just above a noise level.
If the Squelch seems to operate as if it's detecting the signal above the noise floor the radio has - meaning you can set the sq control to quiet the static, then when the radio keys next to it - it senses this and opens and closes when it unkeys - this is a critical stage of operation - which helps you determine the area affected.
Ah, any chance that someone has turned every adjustment screw inside randomly while watching the scale on a wattmeter?
This tends to shut down a receiver.
Just the same, finding out how far "downstream" from the antenna to find the problem starts at the receiver's IF filter. For me it does, anyway.
Find the crystal filter, near the center of the pc board. Now take your "Manual Digital Signal Injector" and touch to the input and output solder pads under the crystal filter.
Yeah, that signal injector. Lay your finger along the shaft of a small screwdriver. Touch the tip to a sensitive spot on the circuit board, and you'll hear either RF noise from your surroundings it it's an RF circuit, or an audio hum, if it's an audio circuit.
And if you can't get any noise from the speaker this way, that points to a problem downstream from that point in the radio.
If you get loud raucous noise from one signal pad under the filter, and somewhat less from the other one, this points to the next stage upstream for the answer.
73
This tends to shut down a receiver.
Just the same, finding out how far "downstream" from the antenna to find the problem starts at the receiver's IF filter. For me it does, anyway.
Find the crystal filter, near the center of the pc board. Now take your "Manual Digital Signal Injector" and touch to the input and output solder pads under the crystal filter.
Yeah, that signal injector. Lay your finger along the shaft of a small screwdriver. Touch the tip to a sensitive spot on the circuit board, and you'll hear either RF noise from your surroundings it it's an RF circuit, or an audio hum, if it's an audio circuit.
And if you can't get any noise from the speaker this way, that points to a problem downstream from that point in the radio.
If you get loud raucous noise from one signal pad under the filter, and somewhat less from the other one, this points to the next stage upstream for the answer.
73
You'll need to continue finding where hum from your fingers touching the board brings up the volume heard in your speaker.
This means then the RX section and the PLL VCO sections need work.
Receiver hiss is what you're trying to establish, but if the means to bring what is heard on air to hear thru the speaker - can't get processed - we have to find where - as in how far back from the receiver - in the audio section - do we hear that static.
This means then the RX section and the PLL VCO sections need work.
Receiver hiss is what you're trying to establish, but if the means to bring what is heard on air to hear thru the speaker - can't get processed - we have to find where - as in how far back from the receiver - in the audio section - do we hear that static.
Loud enough in volume to operate the volume control?
IF so then you just have to find the reason why the PLL is not making an IF signal to get the IF strip to select a channel and process it.
Usually there is an RX indication "Green light" so to speak - that is dependent on the PLL "In Lock" condition - so if no Green light, no PLL communication attempt to get the VCO to try and lock in.
So to help with that these things are a lot like but not exactly to a 148 - but L13 and L14 and L18 I would look into is seeing if the Green RX light can return.
So tune radio to channel 1 locate TP9 (Bare lead of R72).
Using a voltmeter - Positive to TP9 - Negative to Can (or foil ground has to be negative common to the power supply negative) and adjust the L13 (Might be labeled L19) can - by that flat-pack vertical IC UHIC007 - and see if TP9 goes anywhere - try to set it to 3.2 V on channel 1 and put a 50Ω Dummy load on the antenna jack to protect the radio from accidental keyup.
IF no luck - work L18 (L27 maybe) and look at TP9 reading and see if it will come to 3.2V - then hold adjustment right there...
Turn Channel selector to 40 - does TP9 go to 1.2V or thereabouts? Tweak L18
to help center the VCO to the 40 channels this thing can go - so 1 is the lower limit - 40 is the upper - L13 and L18 work this.
Then L14 can be peaked from that. That is the IF output for the thing to even find a channel - you may start to hear receiver hiss during this process - GREAT - then you are well on your way.
IF so then you just have to find the reason why the PLL is not making an IF signal to get the IF strip to select a channel and process it.
Usually there is an RX indication "Green light" so to speak - that is dependent on the PLL "In Lock" condition - so if no Green light, no PLL communication attempt to get the VCO to try and lock in.
So to help with that these things are a lot like but not exactly to a 148 - but L13 and L14 and L18 I would look into is seeing if the Green RX light can return.
So tune radio to channel 1 locate TP9 (Bare lead of R72).
Using a voltmeter - Positive to TP9 - Negative to Can (or foil ground has to be negative common to the power supply negative) and adjust the L13 (Might be labeled L19) can - by that flat-pack vertical IC UHIC007 - and see if TP9 goes anywhere - try to set it to 3.2 V on channel 1 and put a 50Ω Dummy load on the antenna jack to protect the radio from accidental keyup.
IF no luck - work L18 (L27 maybe) and look at TP9 reading and see if it will come to 3.2V - then hold adjustment right there...
Turn Channel selector to 40 - does TP9 go to 1.2V or thereabouts? Tweak L18
to help center the VCO to the 40 channels this thing can go - so 1 is the lower limit - 40 is the upper - L13 and L18 work this.
Then L14 can be peaked from that. That is the IF output for the thing to even find a channel - you may start to hear receiver hiss during this process - GREAT - then you are well on your way.
Then don't worry, at least it's now looking like it's locked...on channel 1
Still get hiss on Channel 40? And a Green RX Light?
So that is ok.
You now have to start looking for a schematic...
Because if you can't seem to hear any signal - you're going to have to look for voltages - signal - noise - in order to help you align the radio.
As this point in time "align" needs to be conferred (referred to) over to "possible repair" as a part, or set of parts, might be bad.
How's your soldering skills?
Still get hiss on Channel 40? And a Green RX Light?
- By tweaking L13 - you can find that the Hiss centers in a specific spot on the slugs' position in the can.
So that is ok.
You now have to start looking for a schematic...
Because if you can't seem to hear any signal - you're going to have to look for voltages - signal - noise - in order to help you align the radio.
As this point in time "align" needs to be conferred (referred to) over to "possible repair" as a part, or set of parts, might be bad.
How's your soldering skills?