Panasonic RC-X210 humming and fast clock

[sfm153]

I have a Panasonic RC-X210 Stereo FM Dual Alarm Clock Radio which only yesterday started to hum while the radio was off. Though not so noticeable when the radio is on, it is still there. I then noticed that the clock is also extremely fast, advancing one minute on the display every two seconds. I opened up the case and see no obvious failure like swollen electrolytic capacitors or burnt resistors or the like, and the transformer is securely mounted. If I disconnect the speakers there is no hum so it is not the transformer itself that's the mechanical source of the hum.
As an aside, I notice that the display is garbled and incomplete if the 9V backup battery is disconnected - another new situtation.
I'm wondering if anyone can suggest where to look/check to remedy this problem.

 

[73's de Edd]

Sir sfm153 . . . . .


Your giving that model number reveals that to be a circa 1991 vintage unit . . . .right-o ?
Considering that the clocks electronics is . . . NOW . . . . relying heavily upon the steady state DC output of the back up battery . . . to even get a cognizant display . . . smells of a power supply problem . . . along with the also mentioned present suibtle hummmmmmmmmm . . . .chum.

If I were to tell you that the unit relies upon a switch mode power supply feeding power to that circuitry; and its performance has gradually declined to the extent that it is additionally feeding " trash city " into your systems power supply.

Would you then be able to locate that units main filter and substitute in another same value unit by solder tacking its leads in acrosss the original unit and then evaluating the units timekeeping ability ?

Thus, confirming your having basic component identification aptitude, schematic reading, tear down / access skills and soldering skills ?

If so, I will pick up that units schematic and pull and digitize repair info the next time I'm out to the "mule barn" with its adjunct archival printed technical storage area.
Been wet and only Jeep weather, so some dry out days needed to be able to ford the ruts.

73's de Edd . . .
. . . . . . . . . . .

There was a power outage at a department store yesterday. . . . .
with upwards twenty people getting trapped on the escalators.
That is . . . by happenchance . . . that Steve Tyler of Arrowsmith, shopping down
on the main floor, happened to look up and see their dilemmna.
He then shouted out a chorus of " WALK THIS WAY " . . . . as he broke into a strut.

 

[sfm153]

Super; thanks for the reply!
I've got a schematic coming by next week so will take a look at it with your suggestions in mind.
To show my electronic ignorance, having only assembled a few Heathkit items (scope, sine/square wave generators, and multimeter back in the 70's) what would the filter portion likely consist of? Capacitor, resistor, transistor, diode, one or more?
Have a good soldering station and moderate ability otherwise, so up to the repair if I know what to repair.
66 at noon here in Tucson though snow the other day. Took 7 minutes with a high power car wash wand to get the clay/mud off the undercarriage of my Tacoma after a visit to Whitewater Draw to see the Sandhill Cranes come in, so can relate to the ruts . . .