UNIDE MADISON ISSUE. HELP!

[Stellasarat]

My Madison abruptly stopped operating.
This happened while I was modulating on single side band.
Here's what's happening.

No output on AM whatsoever, but is showing modulation on the rigs modulalton meter.
Showing nothing on rigs output or external watt meter.

No single sideband output whatsoever (when modulation is added).
I don't think its major but it's obviously a problem that needs to be addressed as it's basically a paperweight right now..

 

[Robb]

Probably lost a final or driver.

 

[Stellasarat]

Probably lost a final or driver.

Thank you very much my friend. I just checked again and taking a closer look at the external output meter I am showing somewhere in the mila watts of output, very low just barely moving the needle but with modulation it is showing very very little output. Modulation external meter is showing some modulation but downward. Thank you so much appreciated I hope some others way and maybe this extra information will help you to help me decide what it most likely is

 

[Robb]

Thank you very much my friend. I just checked again and taking a closer look at the external output meter I am going somewhere in the middle lots of output very low just barely moving the needle but with modulation it is showing very very little output. Modulation external meter is showing some modulation but downward. Don't know if this will help you but I also suspect probably a final. Thank you so much much appreciated I hope some others way and maybe this extra information will help you to help me decide what it most likely is

DId you recently turn up the modulation output? If so; this will be too much for the finals and will show backwards modulation.

 

[wavrider]

Time to send it off to the tech Stella, hard to diagnose a repair online needs to be on the bench with proper test equipment.

Maybe a voltage regulator, or as Robb said drive or final, could be some old caps finally gave up and shorted out removing voltages from circuits etc etc.

The Madison's as well as other radios with that chassis in their day were GREAT rigs .

They are reaching the end of their operating time unless they are re capped with new electrolytic caps. Originals are getting old and drying up.

 

[Stellasarat]

DId you recently turn up the modulation output? If so; this will be too much for the finals and will show backwards modulation.

Negative Rob. Modulation section in this radio is untouched.

 

[Stellasarat]

Time to send it off to the tech Stella, hard to diagnose a repair online needs to be on the bench with proper test equipment.

Maybe a voltage regulator, or as Robb said drive or final, could be some old caps finally gave up and shorted out removing voltages from circuits etc etc.

The Madison's as well as other radios with that chassis in their day were GREAT rigs .

They are reaching the end of their operating time unless they are re capped with new electrolytic caps. Originals are getting old and drying up.

I think the final or the driver just went but I doubt it had anything to do with the capacitors. All capacitors were replaced about 5 months ago and anything else that could have been replaced inside this radio as far as diodes transistors excetera excetera have been changed, and brand new ones were added. I purchased one of those replacement kits Off ebay, and although my tec usually uses his own said the ones I purchased were of good quality so he didn't mind using them. I told him if they werent good to use the ones that he normally uses but he was satisfied with the quality of them so installed those that I bought off ebay. I don't think it's anything major. I truly believe that you guys are correct and its either the final or the driver. The radio will be going out tomorrow and hopefully I'll have it back by Saturday. I'll let you guys know what it was even before it's repaired. I should get the diagnosis on what the problem is by Thursday. Thanks again you guys are excellent.

 

[loosecannon]

SAR,

would you like to test the driver and final yourself to be sure?

it's not hard to do, if you have a soldering iron and are comfortable unsoldering the legs of the driver and final from the board.

you just lift the unsoldered legs up off the board and you can test the transistors with your digital volt meter.

let me know if you want to try this and ill walk you through it.
LC