[attachment=23716][attachment=23717]I’m a rookie working on a General Electric KL-500. I only have one electrolytic on this radio but it contains 3 sections. C-23 20mfd, C-24 10 mfd and C-16 20 mfd. My ability at this time to properly read schematics unfortunately is limited so I am appealing to the forum for some assistance with where the + and - connections go for the new caps. Photo enclosed of the electrolytic and a screenshot of the schematic as well.
I assume that the + for C-16 goes to where the yellow wire currently is and the + connections for C-23 and C-24 go to the where the three red wires currently are but I want to ensure I ground this electrolytic properly. Where would I ground these caps if I’m going to place all the new caps under the chassis. If I am wrong with my assumptions for the + connections please let me know where they should go.
I realize this is a basic question but I don’t what the mess up the polarity.
Plusses are all in the phenolic bottom and the minus is the can itself, whose twistlock tabs are holding the cap to the chassis and some might be soldered to for the caps' minus.
The photo is not very good. You might want to zoom in on that cap and lower the contrast so the details are seen.
The schematic is very fuzzy but it appears the short bare wire to the 5Y3 is attached to C23, the red wires are attached to C24 and the yellow wire from the 6K6 is C16. If you look closely at the electrolytic pins where they exit the capacitor there is a symbol next to two of them. The square is C23 and the triangle is C24. Like Mike said, the negative for all three is the electrolytic case which appears to be soldered to the chassis. When installing the new caps be sure there are no connections to the old electrolytic + terminals. (I hope you're getting rid of that paper wax cap just north of the slide switch. )
I took the electrolytic cap off to take a photo of it’s values.
Since I took it off and it probably won’t go back on very easily, can I solder the - connections to one of the chassis lugs that is remaining from the original cap. I will hot glue the old cap back on for looks after.
And yes that paper cap is going.
Go by values.
They are denoted by the square, triangle and nothing on the 25V one.
If you look at the phenolic plate where the pins go out of, next to the pins you will see the triangle cutout, the square one and no cutout.
Yes, you can. But, at this point it would make sense to "re-stuff" that can, if you have caps that will fit inside. Just drill holes through the base and hook the new caps to the old connections.
I have two of these, and a post war RCA equivalent. The can of the filter condenser is common negative, it goes directly to chassis. I seem to remember that the original filter caps were 20 and 10 microfarad uf, at 350 Vdc, the third cap is a cathode bypass cap connected to the cathode pin of the 6K6 tube, it's also 10 uf but something like 25 volts. Realistically the original filter cap can is probably too small to restuff, so I would use a terminal strip to install new ones under the chassis, probably under the original can, except for the cathode bypass cap. that can go between the tube socket terminal, and the nearest convenient connection to ground.
Regards
Arran
I did rebuild three of 1" twistlocks.
They are very inconvenient, if you want good quality caps of 10+ uF high voltage caps inside. I had to do that for my EICO tube amps.The caps had to be stacked up. Good thing we are dealing with low frequencies - the wire become really long.
The radio is working very well now. Caps have been replaced as instructed.
My hobby is woodworking and after refinishing radios for other people I got into radio restoration myself.
I seem to have my biggest problems with multiple electrolytic canister capacitors. Where to connect them, ground them, whether work was done in previous years etc. I am reading up on schematics but some of the articles assume you have a background in electronics but thanks to this forum and your patience with my questions I am slowly learning this hobby.
Greatly appreciated! Best of the season to all.
Mike;
The ones they used in these Canadian G.E KL-500s are even smaller then that, maybe 3/4 of an inch across, and 1-1/2 inches tall. I'm sure something may fit, but how long they will last I don't know, would a modern 22uf at 350 vdc be able to take the ripple? Believe it or not I think Bob here has the early production KL-500, those had the P.M dynamic speakers, and a resistor between the two filter caps, the later production ones used a field coil speaker, probably because alnico 5 magnets used strategic metals like nickel, not sure about the cobalt, it's a 1941-42 model.
Regards
Arran