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Author Topic: Need help in identifying a capacitor  (Read 1680 times)
KU4UV
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Posts: 374




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« on: January 11, 2013, 10:08:13 PM »

Hello again everyone,

I have most of the capacitors changed out on the old C.B. I am working on, but I have one electrolytic that I am not 100% certain of the value.  Here is a link to the PDF of the schematic.


http://www.cbtricks.com/radios/president/andrew_j/graphics/andrew_j_sch.pdf

The particular capacitor that I have a question about is C103 which is coming off of pin #3 of IC 3 on the schematic.  As best I can tell, it is a .22uF 16 Volt, but I may be wrong.  The schematic has it marked 16V 0.22/A.  The capacitor is obviously an electrolytic, as one side has a - symbol .The capacitor is marked on one side by a .22/16  There is an "802" marked on one side, and a "M" above the - sign.  Can anyone help me out on identifying this capacitor?  I hope this isn't a stupid question, but this is the first time I have recapped a radio, and I want to make sure I do it right.  Thanks!

73,
Mike KU4UV
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N4ATS
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Posts: 797




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« Reply #1 on: January 12, 2013, 05:14:44 AM »

I just looked , .22 uF / 16 V is correct...

Anything above 16 VDC will work just fine....
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N4NYY
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Posts: 4742




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« Reply #2 on: January 12, 2013, 05:21:32 AM »

Look like a .22uf on the schematic. To verify this you are unsure, if there is another of the same value in the radio, compare its physical size. Electrolytics get much bigger as the voltage capacity increases. A .22uf at 16V should be pretty small.

Just a personal preference. When I recap a low voltage (non tube) radio, I always up the voltage  rating 1 step. I usually use a minimum 25V on anything rated under 25. If something is rated 25, I go to  35. At 50V, I usually stay the same. That is my personal preference, not a rule of thumb. I have found in PCB CBs, that the most failure prone caps were 10V caps. The important thing is to never go below the one you are replacing.

You caught me at the right time. I am recapping a TRC-422A el cheapo CB. This is the radio my dad got me in 1982. This radio has notorious 10V cap failures. Alot of the Uniden made chassis like Cobra and so forth also were notorious for 10V cap failures.
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KU4UV
Member

Posts: 374




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« Reply #3 on: January 12, 2013, 07:50:47 AM »

Look like a .22uf on the schematic. To verify this you are unsure, if there is another of the same value in the radio, compare its physical size. Electrolytics get much bigger as the voltage capacity increases. A .22uf at 16V should be pretty small.

Just a personal preference. When I recap a low voltage (non tube) radio, I always up the voltage  rating 1 step. I usually use a minimum 25V on anything rated under 25. If something is rated 25, I go to  35. At 50V, I usually stay the same. That is my personal preference, not a rule of thumb. I have found in PCB CBs, that the most failure prone caps were 10V caps. The important thing is to never go below the one you are replacing.

You caught me at the right time. I am recapping a TRC-422A el cheapo CB. This is the radio my dad got me in 1982. This radio has notorious 10V cap failures. Alot of the Uniden made chassis like Cobra and so forth also were notorious for 10V cap failures.

Thanks guys.  You are correct about the capacitor being a very small electrolytic.  It is so small that you almost need a magnifying glass to read the numbers.  It is a Sanyo capacitor, about the size of maybe 4 or 5 grains of rice, and it's the only one of that size and value I see in the radio. This particular radio that I am recapping is a President Andrew J.  This radio was manufactured sometime around 1978, from what I can gather from reading on the Internet.  I have tried doing a Google search for a parts list, but have only been able to come up with the schematic, which helps.  This was a radio that my uncle had in a cattle truck on his farm for many years back when he hauled cattle.  It is a good sounding radio, so I thought it would be worth the effort to replace the electrolytics.  I found most of the capacitors I needed at Radio Shack, but will have to order the ones they don't stock.  I did go with higher Voltage ratings on all the capacitors.  There are a ton of 10 and 16 Volt capacitors is this thing.  I took the radio with me a couple of years ago when I drove from Kentucky to Florida to see a shuttle launch.  I know hams nock CB radios, but I never heard a peep on 146.52 the whole drive down there and back, and I talked to plenty of truckers on the CB.

My twin brother who is also a ham recently purchased an old Ms. Pac-Man machine in which the monitor would not work.  After about 10 hours of replacing the capacitors on the monitor circuit board, as well as some transistors and other components, The game now works great.  It is amazing what replacing bad capacitors will do.  I am guessing to just leave the disc capacitors alone?  Thanks guys!

73,
Mike KU4UV
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N4NYY
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Posts: 4742




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« Reply #4 on: January 12, 2013, 09:49:22 AM »

I totally agree that 2M is useless for road assistance. A CB is a nice secret when traveling long distance on the road.

Regarding that .22uf cab. You may have to go to  Mouser or Digikey and get a 50V version. The smaller cap do not seem to come in version below 50V. I do not know for sure, but it may be to keep the physical size the big, because caps have shrunk over the year even though they have the same value.

Also, Mouser and Digikey are much cheaper when buying caps than Radio Shack. They do not have a minimum order and can use USPS for cheap shipping.
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KU4UV
Member

Posts: 374




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« Reply #5 on: January 12, 2013, 11:35:16 AM »

I totally agree that 2M is useless for road assistance. A CB is a nice secret when traveling long distance on the road.

Regarding that .22uf cab. You may have to go to  Mouser or Digikey and get a 50V version. The smaller cap do not seem to come in version below 50V. I do not know for sure, but it may be to keep the physical size the big, because caps have shrunk over the year even though they have the same value.

Also, Mouser and Digikey are much cheaper when buying caps than Radio Shack. They do not have a minimum order and can use USPS for cheap shipping.


Thank you sir,

I order from Mouser quite a lot, and yes they are much cheaper than Radio Shack.  Thanks again for the help.

73,
Mike KU4UV
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