Turntable Restoration

I picked up this turntable from an estate sale and I was assured it was in working order. I didn't find out until I arrived home that it wouldn't power on and the stylus had popped loose. It was still a good deal, but it needed work. After a little restoration I planned on putting it in my record cabinet.

https://www.instructables.com/id/Audio-Cabinet/

Remove the turntable platter, internal cover and bottom protective case.

Inspect the electronics for any potential problems. The power problem with this unit turned out to be with the on/off switched. I bypassed the on/off switch circuit with a piece of wire and the board powered on. I inspected the power switch wiring for any problems, but couldn't find anything. From then on the switch started to work.

Electrolytic capacitors can start to go bad after about 20 years so I decided to replace all of them. With basic soldering tools, I did a little practice soldering and desoldering on an old alarm clock circuit board. I found that 350 C was about the right temperature for both activities.

Each capacitor has a corresponding number stamped on the circuit board. I made a list of these and I recorded the Voltage and Capacitance of each capacitor, which is labeled on their sides. I purchased new capacitors for a few dollars at DigiKey online.

To desolder you can either use a wick or solder sucker. You heat the solder on a component and then suck it up with the solder sucker, which is a kind of manual pump. You can also place the copper wick over the solder and heat it up. The wick will draw up all the solder. Sometimes old solder will not melt easily. A trick to getting it to melt is to add a little new solder, which helps break up the old. Once the solder is removed the joint can then be cleaned with concentrated isopropanol if desired.

Remove the old capacitor and replace it with the new one. It is impotent to notice that the capacitor has a positive and negative end. This is labeled both on the circuit board and on the capacitor. Discharging the capacitors on this project wasn't necessary because they were all low voltage.

Tin the tip of the soldering iron. This means melting some solder on it and wiping off any excess. Now place the tip of the soldering iron on the capacitor lead. Touch the solder to the lead and fill the joint. Do hot touch the solder to the soldering iron tip itself.

Notice that the circuit board is labelled on both sides with the capacitor number. In this case capacitor C203 has been removed and replaced. Place a piece of tape over the capacitor temporarily to hold it in place while soldering the other side.

Trim the leads.

Solder the joint.

Test the weight of the tone arm with a gram scale. Adjust the counterweight until you achieve the correct tracking weight. The manufacturer tracking weight for this stylus is 1.25-1.75. I went with 1.50 grams. This step was done with the old broken stylus to prevent damage. Most turntables have a counterweight that can be adjusted accurately without a scale, but the counterweight on this turntable looked like an aftermarket addition.

Set the value on the dial the same as the tracking weight.

Pull the old stylus off the cartridge and slide the new one on.

If you wish you can also replace the RCA interconnects and solder them to the board. Make sure that the new cables are low capacitance, however.

Question for anyone who might know. Is the capacitor on the left 4.7uF or 47uF? Thanks