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President Madison won't power on

Jim Dickey

That's my real name.
Jun 17, 2017
80
7
8
35
Sandpoint, ID
I hate the name of this radio. Nearly impossible to find anything on Google.

Anyway, this is another base station I got from a super deal a few weeks ago. It did not come with an ac power cord so it's plugged into a power supply at 13.8vdc. Will not do anything when the volume switch is turned on. Someone replaced c303 with a pair of 35v 1000uf caps. R306 might be burned. I replaced c107 which had literally exploded. When I opened the case, pieces came out.

Everything else, although Dusty, appears to be ok.

Any ideas? I'd appreciate it!
 

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With any luck you'll have a mobile DC power cord that fits the 3-pin socket on the rear. Select "DC" on the switch in the rear and see if the radio works on an external DC power supply.

A "super deal" radio may have more problems than just a blown AC power supply. This is the 1978 version of that radio, so the list of 40-year age problems will be on the agenda, depending on mileage. A radio with 500 original miles won't have so many of those. A radio that was run 24/7 for 20 years will have a long list of them.

Better to have the whole picture before you start spending money on fixing that part of it.
73
 
I don't see a switch.

I got a bunch of radios and accessories for 50 bucks and most of them work. Just weeding through the pile.

Pic of back
 

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have you checked to see if there is power at the on off switch. a few of the older radios the on off switch did not last long. check for voltage on both legs of the switch.
 
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Whups!

Wrong "Madison" radio. No slide switch on the rear of this radio.

The pics show the original 4-pin version. Just visible inside the two-prong AC power-cord jack is a tiny plastic cam. Plugging in the AC cord pushes the cam up, and pushes a switch contact to select the AC power.

The DC power jack is active when the AC cord is unplugged.

Pretty sure. Really should pull out Sams CB179 and refresh my memory.

And if it won't power up from the DC power socket, there are still multiple possible reasons for that.

73
 
Lots of good ideas! I really appreciate it. I checked that power was getting to the switch last night but for some reason I didn't check that it was flowing through the switch.

Will advise the status on everything else when I get done framing this basement side job. I really appreciate it guys
 
Check the clock settings. On my Madison (8719PLL, red led clock) there are buttons on the clock for a timer, sometimes I have to fiddle with these when mine does this.
 
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Aha! I took a quick break from my construction project and sat down for a second to look at old president Jimmy. I need to go back inside and retrieve my multimeter I was using for a.c. Wiring but while wiggling a small screw driver behind the volume pot, I got a spark. I did it again whilst looking at the front of the radio and the channel indicator powered on. Looks like a bad switch in the pot.

The question is do I go looking through the junk pile for another dual pot with switches or just leave that pot in the radio and bypass the power switch function to a spst switch installed somewhere on the radio?

Are these things worth enough in stock working order to keep me from drilling a bunch of new holes in it?
 
Life! I twisted the pink orange and red wires from the back of the pot together and she fired right up! Here's the next issue. The receive only plays audio when it's in PA mode and when I key I get zero output and a loud squeal from the external speaker. When I switch back to CB mode, I get no audio but I do get a 6w dead key and a 22w modulation. I'm assuming something isn't right some where. A diode perhaps?
 
Also the clock isn't working. It appears to have a large contact switch on top that wouldn't be accessible with the covers on?

I'm not real concerned about the clock. I have a 6 digit freq counter that would look excellent in the window, as well as opening up two more holes for switches.
 
Jim, if you haven't already come to this conclusion on your own; what you have there is what we like to call a basketcase radio.

I hope you enjoy working on it because you are going to be chasing problems for sure.

the real truth is that your radio is a classic and is very sought after when they are restored, but the biggest detractor from the value is that someone had their inexperienced hands in it and created problems that butcher the radio. things like lifted PC board traces, cracked slug cores, or damage to parts that aren't available any more will ruin the value of an otherwise diamond in the rough.

What im getting at is that you have a very nice radio there that warrants an investment in its restoration, but you need to be realistic in your judgement of whether or not you are the person to attempt it.

also, the first things you should be doing are a full re-cap of the radio and then an alignment. without replacing the caps, you won't know if a bad one caused another problem and you can end up chasing your tail.

You will find a lot of good advice here, but if you don't go about it with a systematic approach and aren't willing to put any money into the radio; you will find people will lose interest in helping you along.

best of luck with it, you have a great radio there for sure.
LC
 

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