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다양한 종류의 Pentax 디지털 카메라 수리 안내서.

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Looking to identify this component in a Pentax 1°/21° spot meter

Hi,

A complement to my previous question: I’m trying to indentify this electronic component in and old Pentax Spotmeter V light meter. It measures 178 ohm, but I’m not quite sure what it is, because it doesn’t really looks like a resistor. It is brownish of color, very tiny (a tenth of an inch or approx.2.5 mm) and has a white painted stripe on it, perhaps a color code. I was thinking maybe a thermistor, but I’m not sure.

Block Image

Any ideas are welcome,

Thanks!

Update (10/12/2021)

The yellow wire comes straight from the contact button and is going to the lamp, it is a sub-circuit. The lamp is there as an extra 'illuminator' to be able to read low light readings (in low light situations) on the scale. Nothing special really. But on the other hand, there is a similar component in red with a black marking, between the red wire going straight from the battery and the yellow wire followed by this brown component going to the lamp. Someone suggested a voltage divider, perhaps this is true: 2 resistors after each other. The red one reads 1.9 kOhm, the brown one 178 Ohm. the voltage of the device is 4.5 V (3x alkaline batteries). The voltage of the light bulb is unknown to me, but it withstands 4.5, I tested it. I don't know of this makes any sense?

But the light of the lamp is now so faint, and isn't working most of the time, that I'm wondering if this is the purpose?

This little PCB is the first one you encounter, btw, it is placed after the battery, so to speak.

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@chris_ifix that is an interesting one. I have tore apart same pretty vintage equipment and have not come across this type of marking. The paint markings was pre WWII and even that was different than the component you have here. I am starting to wonder if this could be non-US non-European component. I have a nixie clock from the former USSR that had similar components but not that type of marking. It is not a prior to current marking code, which was Body, Tip, Spot. Even on those the colours themselves represent the same values as in the modern code. On the one you have as well as the others I linked to, they seem to be indifferent positions i.e. top,middle, and bottom of the component. Some older molded resistors look like small, narrow, mica capacitors instead of the dog_bone style. But those are color-coded by three colored dots. It appears as if even that spotmeter had different version of that component. Take a look on here image 2 bottom right and on on here as well. Image 5 shows yet another version. Personally I would recommend taking another really clear picture and posting it at forums that really deal deep with this stuff. These https://www.antiqueradios.com/forums/ind... or https://www.dtvusaforum.com/forums/vinta... are the ones I frequent.

Yes, the components are a mystery, thank you for the hint. I've just noticed by the way that on the site of Mike Butkus, he made a personal accompanying circuit drawing /redesign of the older Pentax 1/21 model because there seems to have been a frequent problem with the batteries and some design. https://www.cameramanuals.org/flashes_me...

I wonder in how far there are similar issues with the Pentax V spotmeter (although like I said, there are different batteries in it, and a difference in circuit).

@oldturkey03 - These ultra small resistors are used in the camera industry. They predate SMT devices by a few years. I still have a few 1/16 & 1/32 watt when I was fixing cameras when I was in school (70's).

They are hard to find as I think they only where available in Japan (not imported in quantity). I got mine from the camera makers. The markings are difficult to ID as they often didn't follow the standards (no room).

@chris_ifix now I am definitely confused on here. It looks like your questions got merged. Reading through the comments you left on that it appears you already knew all of this. Let me know if there is anything new for you what I left in Answers. That way I can delete it after since this is not an answer and I cannot add images to comments.

@oldturkey03 Hello, yes, I think the answers got mixed up. And Dan is replying to you as well concerning the components from Japan.

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Here’s the repair manual for your meter Pentax Spotmeter V service manual

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Hello,

I’m afraid this is for the much older model, the Pentax Honeywell 1°/21°. This model has still two batteries and a different circuit for each of the readings, being low or bright light and the circuit is also different from the Spotmeter V (as far as I can tell after I opened it). I have already this manual, it could be found on internet, but I’m wondering if it is complete, because no specifications of electronic components are present (if this is standard practice in repair manuals, I don’t know).

Anyway, I appreciate your willingness to help me out, thank you.

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Before we had SMT devices we had small wired devices which someone would hand solder to a board. This is a micro resistor used in cameras and photography meters.

Pentax never offered a full schematic for the meter. But they did offer the analog side which you’ll find in the manual I posted in your other question.

Be careful! The wire legs are easy to snap off. The resistor is part of a voltage divider used to adjust the voltage of the sensor.

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It is possible it is a voltage divider, but it is also placed before the sub-circuit of the lamp, so I'm not sure this adjusts the voltage of the sensor. Probably the voltage to the lamp then?

@chris_ifix The V model is digital with a Red LED display within the viewfinder. By chance do you have the meter version with a needle? Spotmeter 1-21 degrees. It has a tan handle vs the V model which is black. Pentax Spotmeter 1-21 degree

@danj No it is not digital. It is the analog version with needle. Not much different from the 1-21 , except for the fact that 1-21 uses 2 batteries: 9V for low light measuring and 1.3 V mercury for bright light.(or vice versa perhaps).So the circuitry is also different. Spotmeter V uses only 3x 1.5 alkaline batteries (4.5V). I think the digital spotmeter is just called 'digital spotmeter'.The Spotmeter V has a grey casing.https://bwfilmdiaries.files.wordpress.co...

@danj And indeed, there seem to be a black version as well, but mine is analog with needle.

@danj And the bulb is incandescent, not led for certain. Because I'm looking for more information about it and a possible replacement, but it seems to be OEM.

@danj My guess is that is comes perhaps from Honeywell as well, because Spotmeter 1/21 was made for Pentax by Honeywell in America, and perhaps my version also. Although this is pure speculation on my part.

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