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 Post subject: What Cap to use??
PostPosted: Oct Fri 06, 2017 6:50 pm 
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Location: shirley NY...Long Island
Hello all....I am repairing a radio from like the 70's and need to replace the electrolytic caps..and some of them are these specs:
0.1 uf at 50 volts..
0.5 at 10 volts
30 uf at 6 volts

I have done alot of radios but dont know what to replace these with..

Kenny KE4HVE


Thanks...


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 Post subject: Re: What Cap to use??
PostPosted: Oct Fri 06, 2017 9:23 pm 
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Same value and the same (or higher) voltage.

The S/S stuff I've done lately has electrolytics for values like that---and lower. You can use film capacitors---if they fit physically---but the electrolytics are dirt cheap.

Mouser, for one, has a large selection of low-value electrolytics.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Fri 06, 2017 11:12 pm 
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Location: Mountains of Mourne. Ireland.
Modern day electrolytic capacitors have become so much smaller since the 1960's - 1970's

"Good sizes to keep on hand are:
2.2 μF
4.7 μF *
10 μF *
22 μF
33 μF *
47 μF *
100 μF *

Those with an asterisk are the ones I use most often. YMMV.
Anything rated 16V or higher is fine. I tend to use higher values because
the lead spacing matches better and there is virtually no difference in price".

Mitch.


Aluminum-capacitor Parametric search at Digi-Key with radial + 50V selected→ here. Dimensions listed.


From Digi-Key home page, it's... Capacitors... Aluminium Capacitors. Apply your filters, voltage rating + Package/Case i.e. Axial can or Radial can, should narrow the field. oh... It helps to search capacitance ascending, use up arrow, top of capacitance column.
Alternatively, click the up arrow in the minimum quantity column.


Some of the old μF (microfard) values are no longer common... so choose the next nearest capacitance value, up or down.
... I buy the 50V ones today to replace the old 3V, 6V + 10V ones and 85°C is good enough for transistor radios.

It's foolish to hunt down 3V 6V or 7V caps :shock:


Greg.

Edit: If you look at the lead spacing, diameter and height data - (for the 50Volt capacitors referenced above) - you will get an idea how small today's electrolytics have become.
Image
Also, if you have trouble locating axial capacitors, you can bend the legs of a radial cap to suit, just be sure to use some spaghetti or heat-shrink tubing on the bent over leg.


Edit: image updated.


Last edited by egg on May Tue 01, 2018 10:48 pm, edited 1 time in total.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Fri 06, 2017 11:26 pm 
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Location: SoCal, 91387
These start at a dime. You should be able to use the .22 uF in place of a .1 uF;
https://www.allelectronics.com/category ... ial/1.html
Much easier site to navigate.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Sat 07, 2017 12:25 am 
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I second the advice Greg gave (I only stock 35+ volt rated caps myself). Since new capacitors tend to be at the bottom the tolerance listed, i.e. a new 47mfd cap will often test at 43mfd or so, I use 56mfd capacitors to replace old 50mfd caps, because I assume the original manufactures used the cheapest caps they could, so a little over is probably better than a little under.


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 Post subject: Re: What Cap to use??
PostPosted: Oct Sat 07, 2017 4:41 am 
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Location: shirley NY...Long Island
Thanks all...I was just thinking that using those caps that are .22 or 4.7 are almost twice the rating which is in there...so I was thinking it would be the same as the ones in there, that are probley that rating now...I do know the ESR would be extremely small compared to the old ones...

I did find some 0.1 uf caps from West Florida componets..
They were like .15 cent each..
Anyone ever heard of this company???

Kenny...Thanks..


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 Post subject: Re: What Cap to use??
PostPosted: Oct Sat 07, 2017 5:07 am 
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Transistor radios are extremely tolerant of wide latitudes in component values.

As an example, any number of different Transistors can normally be used as replacements for the converter, IF, and audio stages, and give like-kind performance.

AFA caps, I've personally used 10 uF units to replace 47's, and vice versa, with no loss of performance. The only cap I would try to adhere close to, would be the small value going to the VC center lug, and even then, a variance of 10 uF either way shouldn't negatively affect operation.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Sat 07, 2017 10:46 pm 
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Thanks fiftys....this is off subject but you would be the one to ask...I have a computer speaker that uses an IC for the amp..is there any way that IC could make a distorted sound and still work..I thought it would work correct or not a all...thanks..for helping..


Kenny


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 Post subject: Re: What Cap to use??
PostPosted: Oct Sat 07, 2017 10:59 pm 
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Anything's possible, but are there any other components in the circuit, between the IC and the speaker? Also, could be the speaker itself. Try patching in another one as a test.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Sun 08, 2017 12:55 am 
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Kennynva wrote:
Thanks fiftys....this is off subject but you would be the one to ask...I have a computer speaker that uses an IC for the amp..is there any way that IC could make a distorted sound and still work..I thought it would work correct or not a all...thanks..for helping..


Kenny

if your computer speakers are powered by a 9 or 12 volt adapter, usually they are left plugged in 24/7 and may need new filter caps depending on age.

if it's a sealed unit and you can't take it apart go inside the speaker that has the amp and install a filter cap around 2200uf 16 volt or higher at the power input leads. Check the polarity.

if it still sounds distorted, there may be another problem in the amp circuit.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Sun 08, 2017 5:53 am 
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Location: shirley NY...Long Island
I took it apart and checked it with a signal tracer I built out of a computer speaker amp...and found distortion on ONE of the two amp IC's they are TDS2030A ...so I guess it is gone..or going bad..

Kenny


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 Post subject: Re: What Cap to use??
PostPosted: Oct Sun 08, 2017 2:24 pm 
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Kennynva wrote:
I took it apart and checked it with a signal tracer I built out of a computer speaker amp...and found distortion on ONE of the two amp IC's they are TDS2030A ...so I guess it is gone..or going bad..

Kenny

Are you sure the number starts with TDS?

The most common are TDA2030A I use these IC amps myself on a few homebrew projects.

They require a few external components to function properly, so check the caps and resistors that are associated with that IC chip.

Also, check for colder solder joints.

Look this data sheet and see if the component looks the same as yours.


Attachments:
TDA2030A.pdf [104.71 KiB]
Downloaded 49 times

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 Post subject: Re: What Cap to use??
PostPosted: Oct Sun 08, 2017 8:50 pm 
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Location: shirley NY...Long Island
Yes Rocco53, it is a TDA2030A. It was late at night when I wrote that...will do...I will check the components around it..
Another IC is there too...which could be bad...it is a TA8173AP, which does something with mixing both channels to make a more stereo sound from the two amp chips...
Kenny


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 Post subject: Re: What Cap to use??
PostPosted: Oct Sun 08, 2017 9:26 pm 
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Kennynva wrote:
Another IC is there too...which could be bad...it is a TA8173AP, which does something with mixing both channels to make a more stereo sound from the two amp chips...
Kenny

A sound field reproduction IC, they are used for stereo enhancement.

http://www.alldatasheet.com/datasheet-p ... 173AP.html

Not likely the culprit but anything is possible.

If the distortion is only on one channel, I would be looking at the output section.

If it IS one of the output IC's I'm sure you can still get them online cheap.

The ones I have in my parts bin were for older Chrysler AM/FM car radios, so they been around for a while.

Use your signal tracer to check the audio quality at the TA8173 Left and Right Output

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 Post subject: Re: What Cap to use??
PostPosted: Oct Mon 09, 2017 11:08 pm 
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I will try that....Im not happy at this moment...I was adjusting the RED coil(osc coil) on an am radio, and it broke..or cracked, it was close to the correct adjustment...and I can make up the difference with the adjustment on the tuning cap....do you think this is ok..??? and are most the same coils so I can replace it.??

I hate so many questions..but it just happened and I had to tell someone...

Kenny


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 Post subject: Re: What Cap to use??
PostPosted: Oct Mon 09, 2017 11:48 pm 
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Kennynva wrote:
I will try that....Im not happy at this moment...I was adjusting the RED coil(osc coil) on an am radio, and it broke..or cracked, it was close to the correct adjustment...and I can make up the difference with the adjustment on the tuning cap....do you think this is ok..??? and are most the same coils so I can replace it.??

I hate so many questions..but it just happened and I had to tell someone...

Kenny

Don't hesitate to ask questions, that's we are all here to help each other.

If it was the red (osc coil) that broke, then yes! you can adjust the trimmer on the tuning cap.

Iv'e had a few of those ferrite screws break on me. Each coil in a radio has different windings.
Even a red coil from a different model radio may not have the same pinout.

For future reference, the best way to deal with those is to remove the coil from the circuit board. (Take note of orientation)

Carefully seperate the metal housing from the plastic coil assembly, pushing a plastic tool from the top hole usually gets them apart.

Then I just unscrew the ferrite and replace it with one from my junk parts. Re-asseble the coil and install.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Tue 10, 2017 12:12 am 
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Location: shirley NY...Long Island
That is exactly what was going to do...just replace the ferrite core, are the cores the same...even though the color is different???

And yes it has the trimmer on the tuning cap...all this does is set the freq to match the dial right????


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 Post subject: Re: What Cap to use??
PostPosted: Oct Tue 10, 2017 12:15 am 
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Some manufacturers back in the day would put a tiny drop of glue on the ferrite core to keep it from wandering, if you ever run into those again try a little heat from your soldering iron to loosen them.

Most of them just have wax and they melt easily to adjust.

The core material is all the same, they color them to distinguish each coil's function.

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 Post subject: Re: What Cap to use??
PostPosted: Oct Tue 10, 2017 1:12 am 
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Joined: Dec Tue 08, 2015 12:53 am
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Location: shirley NY...Long Island
ok...got it....I bottomed it out, and thought about it about the time it broke...
I did put wax back in there to keep the core from breaking more and coming apart..I cant see any difference when I align it with the tuning cap...instead of the coil...most I have seen use yellow and black for the IF adjustment, but this one uses white and black for the IF..

I dont have a diagram for this radio and cant find it..

It is a (national) Panasonic RF-835.

Kenny


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 Post subject: Re: What Cap to use??
PostPosted: Oct Tue 10, 2017 1:30 am 
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Kennynva wrote:
It is a (national) Panasonic RF-835.

Kenny

Hmm, not familiar with that model, maybe someone else here has info on that radio.

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