Uniden Madison - Why?

[Hawkeye351]

Just got through going through a Uniden Madison (8719).

Radio came to me for low output reasons and the owner wanted the variable key removed that someone else put in.

Well, after going through it, I found the following:

VR10 still intact, but they had another variable resistor coming off that VR10, then 2 wires from that added variable resistor went to a potentiometer mounted on the front of the radio. Why?

So, VR10 was tied in with another VR and went off to another VR (potentiometer). Again, why?

D45 was lifted and a resistor inserted in series with D45. Why?

The bias wire for the final was removed from its tap and another wire spliced into it and went to the 13.80v post on back of the power/volume control.

And of course, the limiter is removed.

Before I fixed all the above, the output was:

AM deadkey variable from 2.5w up to 4w, why? Swing up to 7w peak, no movement in average.
SSB was around 7w.

Now, after I removed all the above:
AM deadkey set to 3w, swing to 12w peak and swings forward up to 6w in average
SSB swings up to 11w.

 

[Hawkeye351]

Well, the backside of the dimmer/button board is toasted.

The resistors and diode I can find around here, but not sure about the tranny.

Are there any subs for that tranny in case I don't have that one?

 

[Dr_DX]

Go here:

Sams PhotoFacts Collection

Dan, Saw the alignment info for the Johnson 4740 from CB-212, thanks for posting that. Any chance I could whine at you for the schematic from that one as well? I've been too cheap to add that volume to my set. You don't have to whine, I will scan the schematic for you.... check here in a few...

www.worldwidedx.com

and ask Dan if he has #230. If he does, ask him to make you a copy of the dimmer/button sub board and it should indicate what TR451 is, At the end of the Madison Photofact, it should also list the part # for TR451 and potential subs.

 

[TM86]

Go here:

Sams PhotoFacts Collection

Dan, Saw the alignment info for the Johnson 4740 from CB-212, thanks for posting that. Any chance I could whine at you for the schematic from that one as well? I've been too cheap to add that volume to my set. You don't have to whine, I will scan the schematic for you.... check here in a few...

www.worldwidedx.com

and ask Dan if he has #230. If he does, ask him to make you a copy of the dimmer/button sub board and it should indicate what TR451 is, At the end of the Madison Photofact, it should also list the part # for TR451 and potential subs.

I've got a copy of #230 here, it only goes up to TR401 in the parts list. I don't think they ever published anything for the digital clock model, just the analog one.

 

[Lkaskel]

Well, the backside of the dimmer/button board is toasted.

The resistors and diode I can find around here, but not sure about the tranny.

Are there any subs for that tranny in case I don't have that one?

View attachment 65485

Mikes radio repair YT channel has a fairly long example of that board and how to make a mod for it. I believe he replaced that resistor and put it on the back of the board and extended it farther from the board. If you can find that vid I think it will help you out.

 

[Hawkeye351]

Wanting to add hi channels to this radio.
Uniden Madison (8719 PLL, PC-411 board).

Will this work on the Madison using the channel 9 button?

Copy and paste
"Remove D28, D29, D30, then on the grant remove the yellow wire (the one that goes to the channel display) from the junction of these diodes and ground it !

Then add a jump wire between pin 10 of the PLL and the junction that the display wire was just removed from."

Also, would I use the clarifier unlock procedure on this radio just as the 148/2000 is done?
Remove D52
Remove R44
Remove R174
Add jumper in place of R174
Replace R175 with a 1k
And wires from clarifier same as 148

This radio has a single clarifier control, not fine and course dual.

 

[Hawkeye351]

Ok, here is what I did for HI channels on the channel 9/off switch:

Removed D28
Removed D29
Removed D30
Removed yellow wire coming from channel display board to main board at the above mentioned diode cluster.
Solder that yellow wire to circuit ground.
Ran a jumper from pin 10 of the PLL to the spot in the above diode cluster where the yellow wire was originally.

Button out:
Regular channels

Button in:
27.445mhz on every channel and channel display goes out.

If I leave the yellow wire in its original place, and solder a jumper wire from that yellow wire over to pin 10 of the PLL, same results, only 27.445mhz.

If I run a jumper from pin 10 of the PLL over to ground, I get the HI channels fine.

What gives?

 

[Dr_DX]

Ok, here is what I did for HI channels on the channel 9/off switch:

Removed D28
Removed D29
Removed D30
Removed yellow wire coming from channel display board to main board at the above mentioned diode cluster.
Solder that yellow wire to circuit ground.
Ran a jumper from pin 10 of the PLL to the spot in the above diode cluster where the yellow wire was originally.

Button out:
Regular channels

Button in:
27.445mhz on every channel and channel display goes out.

If I leave the yellow wire in its original place, and solder a jumper wire from that yellow wire over to pin 10 of the PLL, same results, only 27.445mhz.

If I run a jumper from pin 10 of the PLL over to ground, I get the HI channels fine.

What gives?

Does your radio use the 11.3258 XO? Are the high channels you get by grounding pin 10 = 27.605-28.045?

 

[Dr_DX]

The PA switch is a DPST switch, so if you use it you will only get 1 set of additional frequencies. There are 2 options with a single DPST switch:

ground pin 10 = 27.605-28.045 you probably will have to adjust the VCO to get all of the channels to lock.

Ground pin 10 & 11 = 27.455-27.725 you might have to adjust the VCO.

You need to decide which set of channels you want to determine how to wire the PA switch.



If you are willing to use additional switches, then you can get more channels (use the ANL/NB switch beside it) or install 2 switches on the back of the radio and not use the front ones, you can even install a rotary 2Pole 6Position switch in the headphone jack or on the back of the radio and get 26.815-28.045 (get all channels except "A" channels).

 

[Hawkeye351]

It has the 11.3258 crystal.

I went ahead and put everything back the way it was, and used a separate spst switch mounted in the headphone jack hole. Pin 10 to ground through the switch.

Switch up:
1 = 27.605mhz up to 40 = 28.045mhz
Switch down:
Normal CB frequencies

Just need to broadband the transmit now. Normal channels are up around 12w swing, high channels drop to only 4w swing. VCO is adjusted right, RF Stage adjusted the best it's gonna get. The owner uses channel 40 and 27.855 a lot, so I need power to be the same or close to what it is on channel 40.

Which route should I take?
SO-42
R190
C163

 

[Dr_DX]

It has the 11.3258 crystal.

I went ahead and put everything back the way it was, and used a separate spst switch mounted in the headphone jack hole. Pin 10 to ground through the switch.

Switch up:
1 = 27.605mhz up to 40 = 28.045mhz
Switch down:
Normal CB frequencies

Just need to broadband the transmit now. Normal channels are up around 12w swing, high channels drop to only 4w swing. VCO is adjusted right, RF Stage adjusted the best it's gonna get. The owner uses channel 40 and 27.855 a lot, so I need power to be the same or close to what it is on channel 40.

Which route should I take?
SO-42
R190
C163

L21 is the Tripler. Adjust it to get even performance on 40 & 85. L19 And L20 on the VCO can be tweaked too. You are probably going to lose performance on the lower channels.

 

[Dr. Frankenstein]

Don't forget to Broad-Band receive too .................

 

[Dr_DX]

You can "stagger" tune the inductors for 40 & 85 or you can peak & tune for 27.625 which is halfway between 40 & 85.