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Non polarized radial electrolytic capacitor?

Thread starter #1
Hello everyone. New to this forum but not electronics. Or so I thought. I mainly work on/repair cb and ham radios. But I do dable in home stereo receiver repair if I think I can. Mainly recaps and power supply rework.

But I have hit a snag. Recapping a 1992 Technics SA GX330 home receiver, and I have found some radial electrolytic caps that look non polarized. Also the board icon shows it looks like a standard ceramic disk cap.

Circuit diagram and parts list show it just like the rest of the electrolytics in there.

My question is this: Must a non polarized be placed back in the replacements spot and how is a non polarized oriented? Does orientation even matter?

Thank you and any/all replies welcome.
 

dknguyen

Well-Known Member
Most Helpful Member
#2
Orientation does not matter for non-polarized capacitors. Whether you must use a non-polarized as a replacement depends on what the cap is doing in the circuit. You can use non-polarized in place of a polarized, but not vice versa.

What makes you think the electrolytic caps look non-polarized? Shows us the diagram and photos of the caps.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
#3
What value is the capacitor? A lot of times to save cost an electrolytic 1-10 uF is used where a Polyester cap should be. e.g. coupling caps.
The typical symptom is hum and DC offset, sometimes distortion.
 

audioguru

Well-Known Member
Most Helpful Member
#4
When I worked for a Japanese audio products company, many of their circuits used non-polarized electrolytic capacitors.
 
Thread starter #5
Thank you for the responses. On my cell and not at the bench at this moment. But I think the manufacturer is Murata. Caps have an upper case M inside of a box. Looks like a series BP and SU.

Some of the values are: 2.2uF 100v, 22uF 16v and a few others. The 22 at 16v has 2720 in red running horizontal around the diameter.

I can provide a service manual in pdf when I get back in front of the laptop later on or tomorrow. The pdf I have is for the GX350 receiver but they are almost identical.

The big boy 10,000uF 71v audio caps are still on the way from China. Cheaper and they are guaranteed new Sony brand.

Thoughts?
 

tomizett

Active Member
#6
That would be Matsushita (Panasonic). They still make nonpolarised radials in the FC series, I believe, but they're a bit harder to find than the normal ones.
 

unclejed613

Well-Known Member
#7
if you need to replace one of those, you can put two polarized caps back to back ( like this: +O--O+ or this: -O++O- ), and make the caps twice the value of the original, so, for 22uF, use two 47uF caps (electrolytics are generally +/-20% tolerance). make sure the voltage rating of the caps is equal or higher than the voltage for the original. some people say to put back to back diodes across them, but if it's in an audio signal path, that's a bad idea. i have noticed bipolar caps tend to dry out easily. they used to use bipolar caps to couple the vertical yoke coils to the vertical amplifier output in computer monitors, and the bipolars were always the first to dry out in a monitor. also, what tomizett said is correct, the square-M marking is a Panasonic (Matsushita) logo. Panasonic makes fairly good capacitors.
 
Thread starter #8
Thank you for all the responses. I now have the correct service manual for this model. I am trying to screen shot a pic of the main PCB schematic I have in my PDF that has the caps in question for those who asked. The schemo symbol is similar to a polarized but slightly different and also has a capital N inside a circle just below it. I assume this means non polarized?
 

audioguru

Well-Known Member
Most Helpful Member
#10
If the power supply is positive and negative then many coupling capacitors should be non-polarized.
 

audioguru

Well-Known Member
Most Helpful Member
#16
The capacitors you listed have a Note 1 on the parts list. Does Note 1 say that they are non-polarized or say a non-polarized type like a film type?
 
Thread starter #17
audioguru, that is an exclamation mark inside of the triangle. The manual specifies that this means that the component is or has fire retardant materials, high quality audio properties and low noise. Parts list says nothing about non polarized caps.
 
Thread starter #18
Got the big boy 10,000uF audio caps today from China. Indeed they are genuine Sony, (Nippon Chemi-con), caps that test correctly. The originals I believe are Matsushita. They test high ESR and high leak voltage. Also 1 cap is bulging at the top a bit. Into the f-it bucket they go.
 
Thread starter #19
A quick update on this project...... she fired right up with no problems and everything works like OEM. I used the light bulb technique for my current in-rush protection circuit and bulb dimmed like it should have. I ended up ordering the Nichicon bi-polar caps from Digikey last week.

Thank you for all the help and replies. Now, next on the bench is an old Realistic STA7 receiver that was taking the place of this Technics. Everything works perfectly but I think a re-cap is in order and maybe adding a small fan. She does get a bit too toasty for my liking!

Again, thank you and remember, I'm pulling for ya... we're all in this together! (courtesy of Red Green)
 

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