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RCA K130 RC501a chassis - Printable Version

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RCA K130 RC501a chassis - murf - 01-08-2012

Pick up an old RCA K130 yesterday and discovered it needs a new tone control swith.
It has the phenolic busted in about 3 pcs.
Anyone know where I could find one of these?
The motor for the electronic tuning isn't working either.
It will engage the drive wheel,but will not rotate.Just humms.
Anyone have any luck repairing one of these?
Thanks for your help.
murf

Re: RCA K130 RC501a chassis - Sean - 01-08-2012

I can't help on the tone switch. The tuning motor has a non-polarized electrolytic capacitor connected to it. If the capacitor is leaky (as it most likely is) the motor will not work. Also, there is a rubber "clutch" attached to the motor shaft that engages with a wheel to move the tuning capacitor. That rubber "clutch" is probably hard as a rock. When I restored one of these I bought a length of rubber rod from McMaster-Carr to make a new "clutch" from. I cut a piece to the proper length and chucked it up in the drill to sand one end to the proper profile for mating with the wheel.

Re: RCA K130 RC501a chassis - murf - 01-08-2012

Sean Wrote:I can't help on the tone switch. The tuning motor has a non-polarized electrolytic capacitor connected to it. If the capacitor is leaky (as it most likely is) the motor will not work. Also, there is a rubber "clutch" attached to the motor shaft that engages with a wheel to move the tuning capacitor. That rubber "clutch" is probably hard as a rock. When I restored one of these I bought a length of rubber rod from McMaster-Carr to make a new "clutch" from. I cut a piece to the proper length and chucked it up in the drill to sand one end to the proper profile for mating with the wheel.
Thanks for the info.
I will take a look at the caps.
Could I possibly retro-fit a rotary style tone control?
I have a junk philco chassis that has 2 of them.
Thanks
murf

Re: RCA K130 RC501a chassis - murf - 01-09-2012

Sean Wrote:I can't help on the tone switch. The tuning motor has a non-polarized electrolytic capacitor connected to it. If the capacitor is leaky (as it most likely is) the motor will not work. Also, there is a rubber "clutch" attached to the motor shaft that engages with a wheel to move the tuning capacitor. That rubber "clutch" is probably hard as a rock. When I restored one of these I bought a length of rubber rod from McMaster-Carr to make a new "clutch" from. I cut a piece to the proper length and chucked it up in the drill to sand one end to the proper profile for mating with the wheel.
Replaced the .01 non-polarized cap to no avail.
Still won't spin.

Re: RCA K130 RC501a chassis - Sean - 01-09-2012

C44 is a 60uF non-polarized electrolytic mounted on the front side of the motor. Look at the under chassis view on page 3 of the schematic:

http://www.nostalgiaair.org/PagesByModel/505/M0015505.pdf

You might be able to do some rewiring to replace the tone switch with a potentiometer but I would try to get a switch before going through that trouble.

Re: RCA K130 RC501a chassis - Radioroslyn - 01-09-2012

The .01 paper cap is to help eliminate noise from the motor. As Sean sez the 60mfd Non polarized cap is the starting cap for the motor.
Terry

Re: RCA K130 RC501a chassis - murf - 01-09-2012

7estatdef Wrote:The .01 paper cap is to help eliminate noise from the motor. As Sean sez the 60mfd Non polarized cap is the starting cap for the motor.
Terry
Looked at the schematics,and see it there.
The radio has been re-wired and a few caps re-placed years ago.
Only other caps I can see are a couple electrolitics soldered in on the side of the motor.
They are wired to one of the motor terminals.
Kind of wonder if they screwed something up when they did it?
I could send a picture of the tuning motor if that helps?
ANyone know if the dial lights are all #47 bulbs?
The schematics say #47 and #44,but say which goes where.
There are 3 bulbs on the dial.
Thanks for the good info guy's.
murf

Re: RCA K130 RC501a chassis - Radioroslyn - 01-09-2012

Some folks will try putting two electrolytic caps - to + and - to + to make a non polarized cap. The 44 and 47 are the same voltage but different current. 44 is 250ma (brighter) and the 47 is 150ma.
Terry

Re: RCA K130 RC501a chassis - murf - 01-10-2012

7estatdef Wrote:Some folks will try putting two electrolytic caps - to + and - to + to make a non polarized cap. The 44 and 47 are the same voltage but different current. 44 is 250ma (brighter) and the 47 is 150ma.
Terry
Must be what they did.
Will see if I can clarify that.
Thanks
murf

Re: RCA K130 RC501a chassis - murf - 01-10-2012

Sean Wrote:C44 is a 60uF non-polarized electrolytic mounted on the front side of the motor. Look at the under chassis view on page 3 of the schematic:

http://www.nostalgiaair.org/PagesByModel/505/M0015505.pdf

You might be able to do some rewiring to replace the tone switch with a potentiometer but I would try to get a switch before going through that trouble.
Her's the poop on that cap setup on the tuning motor.
Has 2 mfd 20,250 volt dc caps wired together.
Both positive leads together,and of course 2 negative together.
Positive ends are wired to the lead on the tuning motor that also has one lead of the .01 cap.
Can this be right?
murf

Re: RCA K130 RC501a chassis - Sean - 01-11-2012

One lead should connect to the 0.01uF capacitor and the other lead should be connected to ground. You can replace the cap with two polarized electrolytics. You would need capacitors that are twice the capacitance of the original (60uF x 2 = 120uF). I think the voltage from the motor winding on the transformer is something like 24V IIRC. You might double check to be sure. If that is the case then 50V capacitors should be good. Here is a page I found with a discussion on replacing non-polarized electrolytics:

http://www.diyaudio.com/forums/parts/173357-non-polarised-electrolytics.html

They need to be wired back-to-back ("+" of one to "+" of other and connect "-" leads to circuit or "-" of one to "-" of other and connect "+" leads to circuit).

I also found more information on the motor driven pushbutton assembly. It is included in the information on the TRK-12 television:

http://www.nostalgiaair.org/PagesByModel/848/M0015848.pdf

I also found the electrolytic in the parts listing for the TV that shows it is a 60uF 40V capacitor.

When I replaced this capacitor in the unit I restored I just happened to find a 60uF non-polarized electrolytic at a local parts store. Mouser has some 68uF 50V non-polarized electrolytics.

http://www.mouser.com/Passive-Components/Capacitors/Aluminum-Electrolytic-Capacitors/Aluminum-Electrolytic-Capacitors-Leaded/_/N-75hqw?P=1z0wrjxZ1z0yoh9

Re: RCA K130 RC501a chassis - murf - 01-11-2012

Sean Wrote:One lead should connect to the 0.01uF capacitor and the other lead should be connected to ground. You can replace the cap with two polarized electrolytics. You would need capacitors that are twice the capacitance of the original (60uF x 2 = 120uF). I think the voltage from the motor winding on the transformer is something like 24V IIRC. You might double check to be sure. If that is the case then 50V capacitors should be good. Here is a page I found with a discussion on replacing non-polarized electrolytics:

http://www.diyaudio.com/forums/parts/173357-non-polarised-electrolytics.html

They need to be wired back-to-back ("+" of one to "+" of other and connect "-" leads to circuit or "-" of one to "-" of other and connect "+" leads to circuit).

I also found more information on the motor driven pushbutton assembly. It is included in the information on the TRK-12 television:

http://www.nostalgiaair.org/PagesByModel/848/M0015848.pdf

I also found the electrolytic in the parts listing for the TV that shows it is a 60uF 40V capacitor.

When I replaced this capacitor in the unit I restored I just happened to find a 60uF non-polarized electrolytic at a local parts store. Mouser has some 68uF 50V non-polarized electrolytics.

http://www.mouser.com/Passive-Components/Capacitors/Aluminum-Electrolytic-Capacitors/Aluminum-Electrolytic-Capacitors-Leaded/_/N-75hqw?P=1z0wrjxZ1z0yoh9
Thanks for digging that up for me Sean,
I think I will try to buy the right one and install it.
I did send a picture to the forum,but I guess they decided not to post it.
Thanks again,
murf

Re: RCA K130 RC501a chassis - murf - 01-11-2012

Sean Wrote:One lead should connect to the 0.01uF capacitor and the other lead should be connected to ground. You can replace the cap with two polarized electrolytics. You would need capacitors that are twice the capacitance of the original (60uF x 2 = 120uF). I think the voltage from the motor winding on the transformer is something like 24V IIRC. You might double check to be sure. If that is the case then 50V capacitors should be good. Here is a page I found with a discussion on replacing non-polarized electrolytics:

http://www.diyaudio.com/forums/parts/173357-non-polarised-electrolytics.html

They need to be wired back-to-back ("+" of one to "+" of other and connect "-" leads to circuit or "-" of one to "-" of other and connect "+" leads to circuit).

I also found more information on the motor driven pushbutton assembly. It is included in the information on the TRK-12 television:

http://www.nostalgiaair.org/PagesByModel/848/M0015848.pdf

I also found the electrolytic in the parts listing for the TV that shows it is a 60uF 40V capacitor.

When I replaced this capacitor in the unit I restored I just happened to find a 60uF non-polarized electrolytic at a local parts store. Mouser has some 68uF 50V non-polarized electrolytics.

http://www.mouser.com/Passive-Components/Capacitors/Aluminum-Electrolytic-Capacitors/Aluminum-Electrolytic-Capacitors-Leaded/_/N-75hqw?P=1z0wrjxZ1z0yoh9
Does it matter if ac or dc?
Thanks again

Re: RCA K130 RC501a chassis - Sean - 01-11-2012

murf Wrote:Does it matter if ac or dc?
Thanks again

I'm not sure what you are asking about. If you are asking about the transformer voltage then it is AC. If you are asking about the capacitor voltage rating it should be rated for DC voltage. AC voltage is generally shown as the RMS value. To find the peak voltage that the capacitor would see which is what you would want to use to determine the voltage rating of the capacitor you multiply the RMS value by the square root of 2 or 1.414. For 24VAC RMS the peak voltage is 24VAC * 1.414 = 34V. Of course this is only applicable for a sinusoidal AC signal like you get from your wall outlet.

Re: RCA K130 RC501a chassis - murf - 01-11-2012

Sean Wrote:
murf Wrote:Does it matter if ac or dc?
Thanks again

I'm not sure what you are asking about. If you are asking about the transformer voltage then it is AC. If you are asking about the capacitor voltage rating it should be rated for DC voltage. AC voltage is generally shown as the RMS value. To find the peak voltage that the capacitor would see which is what you would want to use to determine the voltage rating of the capacitor you multiply the RMS value by the square root of 2 or 1.414. For 24VAC RMS the peak voltage is 24VAC * 1.414 = 34V. Of course this is only applicable for a sinusoidal AC signal like you get from your wall outlet.
Being new to this,and not being in the electronics field,I am still trying to get an understanding of how these work.
Apparently,the capacitor values are dc voltage?The same for the electrolitics?
Sorry to bug you with such simple questions.
Just want to make sure I know what to buy when replacing that cap.
Have a great evening.
murf