Any one name this part

Started by iccaros, April 29, 2012, 02:18:50 AM

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iccaros

I think they are capacitors,

They are a hollow tube with stripes or some have numbers..

Earthscum

Quote from: iccaros on April 29, 2012, 02:18:50 AM
Any one name this part

Can I name it Cobbleglobber?  ;D

I've never seen caps like that before... not that small, anyways. I saw a couple 40kV caps at one of the flea markets... brass ball ends with a ceramic 3/4" rod between, about 5" long.

They wouldn't be diodes of some sorts, would they?
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iccaros

they are from a 1950's radio. They look like caps in the schematic, but I am making sure..
http://www.antiqueradios.com/forums/viewtopic.php?f=6&t=192258
schematic here
http://www.nostalgiaair.org/Resources/609/M0018609.htm

not many diodes..  Well except the tube type

darron

#3
you say they are hollow? my guess is that it has a wire winding then...

why not just hook it up to a multimeter and see how it measures for resistance/capacitance etc. vs what the colour codes read?
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iccaros

I can not get a read on then in circuit, and after reading this thread http://www.antiqueradios.com/forums/viewtopic.php?t=141088
I am not sure I want to try and test them out of circuit. If this is what they are?

from the thread
"They're ceramic core capacitors and rarely fail.

I have accidentally broken one or two of them with my clumsy fat fingers and long-nose pliers. So take care.

If you read the color code, all the stripes, they're often negative temperature compensating types, like N50 parts per million per degree. You see the copper wire in the associated oscillator coil expands about 28 parts per million per degree Farenheit, and the inductance goes up as the square of the coil's circumference. So to compensate for your average copper coil, you need a capacitor of about 56 parts per million negative. If the tuning capacitor is your usual variable cap, the solution is to put a NTC capacitor with a much larger coefficient in series with the tuning cap, as to bring the combined capacitance to the needed ppm's. This is a very approximate thing and it will over-compensate at the high freqs and under at the lows, but that's about the best that can be done with a variable-cap oscillator.

You also have the problem of positioning the NTC capacitor so it warms up at the same rate and amount as the coil-- this may mean positioning the capacitor soldered to the coil terminal and positioned away from any drafts or convection currents. More an art than a science."

crane

My guess is that it's a 2000pF cap.
I've seen similar tubular creations in old soviet devices.

Jordan A.

#6
2K power resistor?  If you tell us where it is coming from and where it's going I bet we could figure out what it's job is.  Eg. "from the plate of a 12AX7 to the grid of a 12AU7"

They look like old resistors to me though.

cheers,

jordan

:edit: oh, I missed the schematic you posted the first time through.  Umm, I dunno, are there schematic designators that you think belong to the parts?

maartendh

yes, these are (old) capacitors. Usually the  values are in the pico-farad range, I think. Some kind of conductive foil on a ceramic pipe, Sometimes the body wille be painted (gray, or yellow/ brown). Values may be printed or be painted in color code.

Maarten

iccaros

Quote from: Jordan A. on April 29, 2012, 08:36:14 AM
2K power resistor?  If you tell us where it is coming from and where it's going I bet we could figure out what it's job is.  Eg. "from the plate of a 12AX7 to the grid of a 12AU7"

They look like old resistors to me though.

cheers,

jordan

:edit: oh, I missed the schematic you posted the first time through.  Umm, I dunno, are there schematic designators that you think belong to the parts?

Finding them on the schematic part of the problem, as this is a point to point, some points don't make a lot of sense at first. I thought these were cap's but I wanted to make sure, now I should be able to trace them better.

Thanks

Jordan A.

There are a few caps in the parts list specified as "tubular"( I see three), it's kind of hard for me to read but that might narrow it down a bit.

There is a 10 watt 2k wirewound resistor listed, but I don't see any other high wattage R's listed, while we see two big dog bones in the photo.

the mystery lives on,

jordan

Cliff Schecht

Specifically these are old ceramic caps. I say so because I have some like this that say "ceramic" on them. Mine are painted white and are massive for a 30pF cap. I've never used them anywhere..

iccaros

Quote from: Jordan A. on April 29, 2012, 02:14:49 PM
There are a few caps in the parts list specified as "tubular"( I see three), it's kind of hard for me to read but that might narrow it down a bit.

There is a 10 watt 2k wirewound resistor listed, but I don't see any other high wattage R's listed, while we see two big dog bones in the photo.

the mystery lives on,

jordan

The 10w resistor is clear in the equipment.. they are caps,  I was warned not to move them, as they change with heat to stay in sync with the tuning coils of the radio.

PRR

If you "need" the recordplayer function, you do not care about the small caps.

Phono goes into 6AV6 preamp, to 6V6 audio power amp, fed from 5Y3. That's all which needs to work for phono.

Yes, you might want to get the radio working. Do NOT! touch the trimmers on the main tuning cap or the square cans. Trimmers are never the cause of no-reception, they are easily broken and more easily thown so far out of alignment that it won't work. Check tube voltages. Replace _wax_ caps relentlessly.
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iccaros

Good advice, I am not trying to do anymore than I need, I just did not recognize these parts, and wanted to make sure they were not burned out resistors :)

PRR

#14
There are resistors which look like that, but usually bigger. I'd have to feel them to remember the difference.

However that is a common moulded 1/2W 10% part lower down. I assume most of the non-Power resistors in there are like that. Then any funny-stuff is probably a cap. Especially since you seem to have traced it to a possible cap. And it seems to read open (I agree with not cutting it out to check).

And caps like that are not found in the audio path (I would be very surprised). Even if the radio were important, get the audio section speaking first. It should hiss (trace of hum), should HUM! if you touch the Phono jack center, should play "skritch" when you run your fingerprint under the needle, and even play a record (78 only; this will tear the groove out of a 33/45 disk).

BTW: if you adapt a guitar to this "phono" input, it will play. Not loud; it may be hard work to slam the 6V6, but you can tell if it sounds OK or sick. This might be a nice parlor guitar-amp with one stage of preamp between guitar and phono input. Just don't beat the dry old speaker with gross overdrive; or use a different speaker for hard-guitar.
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iccaros

Quote from: PRR on April 30, 2012, 12:52:14 AM

BTW: if you adapt a guitar to this "phono" input, it will play. Not loud; it may be hard work to slam the 6V6, but you can tell if it sounds OK or sick. This might be a nice parlor guitar-amp with one stage of preamp between guitar and phono input. Just don't beat the dry old speaker with gross overdrive; or use a different speaker for hard-guitar.

sometimes its like you read my mind.. :)

I have a nice 1960 Harmony semi-hollow body.. Maybe a slight boost to get the signal to the right level, I would think that it would be a little dirty, with that old speaker anyways.. don't need loud just able to hear it to make it fun.