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President madison/ not working

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Old 07-25-2013, 05:16 PM
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Default President madison/ not working


Hello everyone,
I'm new to the forum, and new to the world of CB's and working on them. I have spent alot of time when i was way younger listening to the locals at night before i went to bed and have always been interested in tinkering. I would like to get my HAM lic. and figured the cb would be a good place to start out. A co-worker gave me his fathers old radio stuff, a model 29, a old midland and the madison you see in the vid along with his base antenna. I got the antenna mounted and have the mast grounded just as his father did except i still need to pound a grounding rod and attactch the ground. for now i have the copper ground stuck about 8" into the ground. A friend of mine just recently got into CB'ing and i figured i would dig out the madison and the other stuff and get it all setup since it was a nice not so hot day today.

Ok so here is whats going on.



I can receive but it doesn't seam to be as strong as my truck with the 102" but i think that is from the base not being tuned and the whip on the truck is. I would have it tuned and plan on it but my friend has my meter.

It sounds like the volume needs cleaned since its scratchy? Where would you start first with this?

This is the 4 pin mic. Would there be any chance the mic is wrong and thats why it won't transmit? There was a midland mic connected to it when i pulled it out of the box.

Thanks


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Old 07-25-2013, 06:07 PM
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IIRC, the 4-pin Madison uses the 858 PLL chip. WHich is a nice radio to work with - provided it works in the first place. They are all getting very old at this point; so they need TLC to bring them back. The problem of no transmit may be as simple as the failure of the keying transistor, a diode failure, or a faulty electrolytic capacitor. You will need to get the schematic for it and trace it through to find the fault. If you don't have the experience or tools; then it might be time to punt.

If you care enough about this old classic; then it might be worth it to send it to a shop and have them check it out, fix and clean, and then have them align it. That is something to consider. It's a keeper - only if it is up to snuff . . .
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Old 07-25-2013, 06:46 PM
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alright, thanks.

I'll have to pull it apart and see if i can dig up the schematic. I want to see if the board is full of corrosion. If it is it will probably just be a chasing one problem to the next.
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Old 07-25-2013, 07:47 PM
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These old Madison radios are awesome. Some of the best ever built. It is common for these to have problems with the caps, due to their age. There are capacitor kits available for them for about $25. Just make sure you get the right kit. There were 4 versions of the Madison. I just got myself a 4th generation Madison and sent it out to have it gone over and aligned. I have$2oo into it including purchase. If you get it working, you are lucky to have had it given to you. Mine in the crown jewel of my radio collection. Good luck with it. I hope it is just a simple fix.

The older Midland radios, even though they had 4 pin microphone jacks, weren't wired the same as the standard Cobra/Uniden type. They looked the same, but were just wired up backward. Try taking the mic from your Cobra 29 and hook it up to the Madison, see if it will transmit. Its worth a try.
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Old 07-25-2013, 11:05 PM
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you may have the wrong mic, or you may have a radio problem.

go to CBTRICKS.COM and look up the cobra 138xlr or the cobra139xlr.
these radios will be almost identical to your madison on the inside, and will show you the correct mic wiring.

just check the jack on the mic with an ohmmeter to see if its wired right.

if that doesnt work, post again and be as specific as possible when describing the problem.

no TX, does that mean carrier with no audio?
no carrier at all?
does the TX/RX light switch over when the mic is keyed?

does it work in any mode? USB, AM, LSB?

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Old 07-26-2013, 12:25 AM
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also check that the relay is switching when you key the radio.

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Old 07-26-2013, 06:09 AM
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Ok i will be able to tinker with it today but it won't be until later tonight. Right now with the mic that was hooked up to it (midland) When i key up There is a small click in the external speaker but it continues to produce sound. No TX light, No carrier/audio. Its just like you haven't even keyed the mic at all. I'm wondering if its isn't the mic being wrong, or the relay isn't working. This is in all modes.

I just have to locate my damn meter, it always walks off somehow.

I'll check those things later tonight and post back.

I also have a cobra 19 that i know for sure is the mic that goes with it as i bought it new and it came with the radio. Will this work the same as the 29's mic? The 29 didn't have a mic on it it came in the box with the madison.

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Old 07-26-2013, 09:20 AM
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Quote:
Originally Posted by mustang_gt_350 View Post
Ok i will be able to tinker with it today but it won't be until later tonight. Right now with the mic that was hooked up to it (midland) When i key up There is a small click in the external speaker but it continues to produce sound. No TX light, No carrier/audio. Its just like you haven't even keyed the mic at all. I'm wondering if its isn't the mic being wrong, or the relay isn't working. This is in all modes.

I just have to locate my damn meter, it always walks off somehow.

I'll check those things later tonight and post back.

I also have a cobra 19 that i know for sure is the mic that goes with it as i bought it new and it came with the radio. Will this work the same as the 29's mic? The 29 didn't have a mic on it it came in the box with the madison.
Yes, the Cobra 19 mic will work the same as the Cobra 29. It is pretty much the "standard" 4 pin that most (4 pin) radios use. I don't know why many (not all) of the Midland radios are wired differently, but they are.

An example, I bought 4 Midland radios at a yard sale for almost nothing. Only one had a typical 4 pin microphone jack. I took a Cobra style mic from my shelf to attempt to test the radio. I turned it on and the meter registered like I was transmitting, only I hadn't keyed up. When I did key the mic, the radio clicked and the meter dropped to nothing. I researched and found that the wiring was different on the Midland radio. It wasn't working improperly, I just had the wrong mic for it.

I am not saying this is what is happening to your radio, just that it is possible. If you have a stuck meter (which is also a common occurrence) it could be that you just can't see it happening. It may end up being a bad cap or relay, but may as well rule out some easy things first. I'll keep my fingers crossed.

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