Uniden Madison stopped receiving

[767 SW Mo.]

My watt meter shows I have a good carrier and modulation swing, my neighbor can hear me but my receive is dead, the meters on the radio don't show any movement either. Anyone have any ideas as to where to start to diagnose the problem, I don't have a repair shop anywhere close. Thanks in advance for any help.

 

[Dr_DX]

Check your RX only 8v source voltage.

 

[767 SW Mo.]

?

 

[sp5it]

All modes no RX?

 

[Dr_DX]

?

LOL. What kind of clock does your Madison have - mechanical or electronic?

 

[9C1Driver]

I would double check all the settings on the front of the radio. You might also try a different mic, a mic has to be plugged in for the receive to work. If you have the red digital clock you could always fiddle with those buttons and see if it pops back in. I think the clock can turn the radio off sometimes but shouldn't effect receive. Hope it's something simple.

 

[nomadradio]

Is your green light on?

Pretty sure that one has a two-color LED on the front panel. Green when receiving, and red for transmit.

If there's no green, that indicates where to look next.

The model name "Madison" could be either one of two radios. The 1978 version is totally different inside from the 1979 version. Quick way to tell is the mike socket. If it has five pins, it's the later version. A 4-pin mike socket suggests the 1978 version. Unless someone altered it.

73

 

[767 SW Mo.]

LOL. What kind of clock does your Madison have - mechanical or electronic?

Clock is electronic

 

[767 SW Mo.]

I would double check all the settings on the front of the radio. You might also try a different mic, a mic has to be plugged in for the receive to work. If you have the red digital clock you could always fiddle with those buttons and see if it pops back in. I think the clock can turn the radio off sometimes but shouldn't effect receive. Hope it's something simple.

did all that, had that happen once

 

[767 SW Mo.]

Is your green light on?

Pretty sure that one has a two-color LED on the front panel. Green when receiving, and red for transmit.

If there's no green, that indicates where to look next.

The model name "Madison" could be either one of two radios. The 1978 version is totally different inside from the 1979 version. Quick way to tell is the mike socket. If it has five pins, it's the later version. A 4-pin mike socket suggests the 1978 version. Unless someone altered it.

73

its the later version all the lights are working watt meter shows I am throwing a carrier and my bubby says he can hear me but my meters on the radio are not moving and I do not even hear any static, speaker works on a different radio and when I key the mike I can hear a click in the speaker.

 

[767 SW Mo.]

I am going to dive into it tomorrow, and run some tests I need to change the 3 way switch for my extra upper and lower channels anyway

 

[nomadradio]

This symptom would be simple to fix if the S-meter were kicking around on channel chatter and noise. Should get at least some hissing noise in either sideband mode.

If the 30-plus year old S-meter were mechanically seized and the pointer stuck, that makes it harder to tell.

There is a 220uf electrolytic cap, just adjacent to the rear half of the TA7222P chip. Don't have access the schemo right now, so I don't know the callout number. This cap is typically rated at 6 or 10 Volts, and will kill all receive audio without disturbing the transmit side. You can check it with an ohmmeter to see if it's shorted. Or you can just unsolder it and see if receive audio comes back. Won't sound right, but won't be dead. Or you could check the DC voltage across that cap while receiving. Should be around 5 Volts DC. And if it measures under a Volt, that's probably it.

73

 

[Handy Andy]

I am going to dive into it tomorrow, and run some tests I need to change the 3 way switch for my extra upper and lower channels anyway

A goofy channel mod can put your receiver IF side - off - as in way off and the Radio won't even let the PLL lock in.

The radio seems to work, at least your friend can hear you.

But with any channel mod, the TX and RX sides need to align right, or you can't hear but you talk to them or you can't get the thing to TX to talk to them, but you can hear them. Your condition seems like this "opposite" so you can talk, but the IF won't align to let you hear.

Try to reverse out that mod, see if the radio can be restored to good health - then carefully redo the mod to eliminate the condition - more than likely the RX and TX IF - the mod threw them off to each other so one doesn't follow or track the other. A loose wire in the mix or a bad/dirty switch contact (read: no voltage or low voltage) does this condition too...

 

[nomadradio]

Just thought of something that would be terribly handy. A set of pictures or diagrams for each of the most common CB or (snicker) 10-meter main circuit boards with the PLL out-of-lock test point clearly identified.

I find it a lot more useful to check this spot in a radio with a 'scope. But some folks have only a meter to work with, and this would simplify making that test.

Finding out if the PLL is locked or not simplifies troubleshooting a "dead" radio.

On the other hand, he did say that it transmits okay. Only the receive side is broken.

Another set of useful pc board pics with pointers would be the IF filter in and out foil pads. This is where the "Manual Digital Signal Injector" can be handy. Your fingertip laid alongside the shaft of a small screwdriver will inject RF noise from your surroundings into whatever you probe with the tip of the screwdriver.

Probing the input pad, then the output-side foil pad on each IF filter can tell you how far downstream from the antenna the receiver has failed. Lotsa noise heard from this test suggests trouble between that spot and the antenna socket. No noise says the trouble is downstream from that IF filter.

73

 

[Rwb]

My watt meter shows I have a good carrier and modulation swing, my neighbor can hear me but my receive is dead, the meters on the radio don't show any movement either. Anyone have any ideas as to where to start to diagnose the problem, I don't have a repair shop anywhere close. Thanks in advance for any help.

sw mo,welcome to wwdx.we must be neighbors . im from southwest mo.about 30 miles northeast of joplin. there are several here that will try to assist you on your radio too. im not up to speed on your radio though