Motorola 53C Clock Radio

This radio came from my wife's grandmother.  It was her bedside radio for many years .  It was passed down to my wife and she had it on her dresser. She had not yet tried to use it as a clock, or a radio.   I offered to check it out and make sure it was working before she put power to it.

The radio is another "All American Five" configuration with five tubes.  This one uses the 12AT6 instead of the 12AV6 for the detector/first audio amplifier.  Tube compliment is 12AT6, 12BA6, 12BE6, 35W4, and 50C5.

Tube compliments in the All American Five can very.  For anyone interested, here are some of the typical tube numbers .

Tube Type	Pentagrid Converter	IF	Detector	AF	Rectifier
5 Pin Early Style	6A7	6D6 or 78	75	43	25Z5
Octals with Anode Cap	12A8	12K7	12Q7	50L6	35Z4
Octals w/o Anode Cap	12SA7	12SK7	12SQ7	50L6	35Z5
Miniature "Peanut" Tubes	12BE6	12BA6	12A6 / 12AT6	50B5 / 50C5	35W4

Back to the radio..

On initial power up,  there  was the typical 60hz hum you hear when the filter capacitors have failed.  I removed the original and replaced it with new Electrolytics.

I've started getting in the habit of testing my capacitors after I pull them out.  Here's how this old paper electrolytic faired. 

Section	Labeled Capacitance	Actual Measured	Replaced With New
1	150V 50 uf (MFD)	.078 uf (MFD)	160V 68 uf (MFD)
2	150V 50 uf (MFD)	.070 uf (MFD)	160V 68uf (MFD)

New capacitors in place. 

Here it is with the old one in place for size comparison.

 

Second problem appeared to be a broken screw mount for the chassis.  The broken off piece was rattling within the case.  This was repaired with Epoxy.

Third problem was a groaning/whirring noise from the clock movement.  This clock has a classic "Telechron" movement.  It's a sealed inductive gear system that uses the 60hz power to run a gear reduction motor.  Removing the clock mechanism would involve removing the front.  This meant I had to pry off the plastic cover to the radio dial. This is where you have to pry VERY CAREFULLY.  

Here's the clock internals.

The Telechron movement was an H3 Model.  Turns out, you can purchase these rebuilt.  I found a very nice web site with rebuilt version of all the Telechron movements.  What a great site!!  Since this is a learning project (as are all my projects), I decided to try to lubricate the movement myself.  I used 3-in-1 oil (my go-to oil for these kinds of things).  The movement is sealed so there's no way to oil it directly. I put the oil around the gear and tried to work it in by moving the gear up and down as much as it would move.  A  small amount did appear to leak past the gear.

I then re-installed the motor.  It was reasonably quiet.  If the problem comes back, I'll probably revisit the Telechron rebuild site and pick up a fresh H3 movement, but this one is working fine for now.  I'm not sure how much my wife will be using the clock so I'll let her decide if she wants to keep it running or not.