Uniden President (yes both) Washington no RX or TX

[357]

Just got this today, mint condition.
RX is dead, hiss but no static, TX the light goes from green to nothing, no red and no RF and the MB3756 no volts on pin 1

Is it the regulator or a cap shorted?
Anyone with this problem in the past?

I seen the power supply was cranked up to 14.8V and read that type of thing takes out the 8V regulator.

Just trying to get some input before I blow a new MB3756


Also is this a rare version? Uniden President Washington

 

[357]

OK I lifted pin 1 and there is 8V there so looks like C66 is the issue....I hope


http://www.radiomods.co.nz/forum/viewtopic.php?t=2088

 

[357]

well that was the fastest repair I ever made...C66 shorted

 

[sonoma]

good find. when you have a audio problem the 1st place I start checking is around the audio IC where the caps hook up. they are bad about shorting out. I would change all the 10 volt caps and the ones around the audio IC and 8 volt reg. to save having another go bad. all the 10 volt caps should be changed to 16 to 25 volt to help with them going bad. these radios are getting to be about 30 years old and electro caps only last about 20 years.

 

[222DBFL]

And set the voltage down on the power supply to at least 13.8vdc max!! Someone trying to get more watts out sounds like with it at 14.8vdc. Good find and glad you got it working so fast. Keep up the good work man. Have fun with it as well.

 

[357]

And set the voltage down on the power supply to at least 13.8vdc max!! Someone trying to get more watts out sounds like with it at 14.8vdc. Good find and glad you got it working so fast. Keep up the good work man. Have fun with it as well.

I put 13.95 to allow for voltage sag....good enough.
Those 10V caps really suck.
Things loaded, 26.815 to 28.045
I placed it in the closet for now, been cleaning up a frg 7700 I got too and a palomar ssb 2900.

 

[midnight special]

here some info,,,,,

http://www.qsl.net/kf6foz/transitional/transitional.html

 

[Yeti Communications Ltd]

washington (pc385)
replace C79 also while you have lid off ...the most common issue with that board is ssb tx audio drops(with rf power) ..again a pesky 10v cap

 

[357]

here some info,,,,,

http://www.qsl.net/kf6foz/transitional/transitional.html

ya I seen that, but mine seems to be a 4th version no?
Uniden & President?

 

[Robb]

ya I seen that, but mine seems to be a 4th version no?
Uniden & President?

That would be a PC-385 chassis with a 8719 PLL chip.

 

[357]

That would be a PC-385 chassis with a 8719 PLL chip.

ya I'm just saying the faceplate....

found 1 on youtube

 

[midnight special]

how many pins does the mike have? does it have 3 buttons on front instead of 2? the president found under the channel selector is on some of the first transitionals,,then it was elimanted when the president brand was totaly used up,,,,

 

[cbdoodler915]

Any further cap issues repairs in 05-2022 please update.
Including better AM regulators that are common on Amazon website for loss of AM transmit thee radios are getting old serveral bough as parts no pll or just tx some with awful mic tone on SSB?