identification of two other components - Page 1
Forum section: electronics / beginners

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 10:19:28 am
content: I'm looking for the identification of two other components (hopefully the last).I think the left one in the image is a diode? A plastic like rounded barrel like item divided in two colors, red/white (upper/lower).The second one on the right of the picture should be a resistor, but I'm wondering from which company?Is says CM (with the M embedded in the C) and then U(?)332Thanks!

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 03, 2021, 10:24:08 am
content: Seems a led and a 3.3nF ceramic capacitor.

author: Zero999
author_rank: Super Contributor
timestamp: November 03, 2021, 10:35:25 am
content: Capacitors are normally specified in picofarads, 0.001nF, or 0.000 001µF. The first two digits give the value and the last the number of zeros, so 332 is 3300pF, which is the same as 3.3nF, or 0.0033µF.If there are two digits, they both represent the capacitor value in pF, so 10, 4.7 are 10pF and 4.7pF.I don't know about the red and white component. How many leads does it have? My guess would be an LED, or photo-diode/transistor, with low confidence.

author: vk6zgo
author_rank: Super Contributor
timestamp: November 03, 2021, 11:36:26 am
content: Quote from: Zero999 on November 03, 2021, 10:35:25 amThe packaging of the right hand component screams "capacitor", but I have run into a resistor in that package.Resistance measurements across it looked like a nearly shorted cap, but "drilling down" in the rather small schematic disclosed it was really a resistor.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 11:47:17 am
content: It is underneath the PCB as a bridge over the in and out of a trimpot, difficult to explain.And the out of the trimpot finally goes to a board ground. And also to the minus voltage pin of an op amp, if I'm not mistaken. So it looks like connecting the positive side of the circuit to the negative side. I thought it had something to do with reflow of current like a diode but I don't know. But I'm pretty sure it isn't a led, it doesn't glow nor are there leds in the circuit.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 11:48:59 am
content: Capacitor? I see.The fact is that there is a marking on the PCB saying 'R9', so I supposed this was a resistor. I will measure it.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 11:50:40 am
content: On the PCB it says R9 so I thought it was a resistor. The only marking on the entire PCB by the way.I will try to measure it.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 12:24:26 pm
content: Quote from: Zero999 on November 03, 2021, 10:35:25 amRegarding the brown one: it gives a multimeter reading of approx.584 ohm. So probably a resistor after all?Considering the fact that I only have a basic multimeter and the component is still in the circuit.

author: Zero999
author_rank: Super Contributor
timestamp: November 03, 2021, 12:29:47 pm
content: Quote from: Chris_D on November 03, 2021, 12:24:26 pmNo, it's a capacitor. It should measure open circuit, but doesn't, because it's still in the circuit so there are other components interfering with the measurement.

author: DavidAlfa
author_rank: Super Contributor
timestamp: November 03, 2021, 12:30:13 pm
content: You shouldn't measure a component in-circuit. Everything connected to it will affect the reading.Desolder it and measure again.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 12:30:53 pm
content: Quote from: Zero999 on November 03, 2021, 10:35:25 amTwo leads by the way. It forms like a bridge underneath the PCB. I was thinking of rectifier diode, because I think it maybe has something to do with the polarities: it starts on a positive pad and then going to a pad connected to minus voltage of opamp and also board ground.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 12:32:52 pm
content: Ok, then I will leave it for the time being, because it is rather difficult to unsolder it. If it is a cap then I believe you.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 12:54:02 pm
content: Actually there is one last thing I wanted to ask: There are tiny white elements in this circuit on the pads, are these like PCB bridges, I don't know how it is called: 'jumper' perhaps?

author: Fraser
author_rank: Super Contributor
timestamp: November 03, 2021, 01:21:22 pm
content: For information…. The original picture shows a red LED commonly found in consumer equipment of a certain age. The component on the right is made by Murata and has the ‘M’ surrounded by a ‘C’ logo. I will need to see if I can identify the exact component though.Your last picture appears to show an early version of a thick film precision resistor.What is this equipment please ? A vintage multimeter ?Fraser

author: Zero999
author_rank: Super Contributor
timestamp: November 03, 2021, 01:38:43 pm
content: Quote from: Chris_D on November 03, 2021, 12:32:52 pmDon't take my word for it. Do an image search for ceramic capacitor and note that some of the parts look similar the part in your photograph.Quote from: Chris_D on November 03, 2021, 12:54:02 pmIt would be easier if you posted complete pictures of the board, with the components you need help identifying annotated.

author: TimFox
author_rank: Super Contributor
timestamp: November 03, 2021, 02:03:15 pm
content: The "CM" trademark is for "Ceramite", a ceramic capacitor manufacturer formerly part of Sprague. Vishay bought the company and moved production from Wisconsin to the Czech Republic.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 02:05:18 pm
content: Quote from: Fraser on November 03, 2021, 01:21:22 pmAlmost, it is a photographic light meter by Pentax. the Spotmeter V, and according to the date on the opamp in it, made by Intersil, and identified by somebody here on the forum, for which I'm very grateful, it is made in 1984, although I thought it was made earlier. The first models of spotmeters dating back already from the 1960's.It is much like an ampmeter I guess, which is in it, but the current comes from the light measured by a light cell, probably already silicone, not Cds, but I should verify that.BTW,by thick film precision resistor: are you referring to the tiny white elements?

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 03:46:41 pm
content: Quote from: TimFox on November 03, 2021, 02:03:15 pmThanks Tim.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 03:53:43 pm
content: Quote from: Fraser on November 03, 2021, 01:21:22 pmI think that the tiny white elements are indeed film resistors of zero ohm, so jumpers. Probably to fix or reinforce the solder pad.https://nl.farnell.com/yageo/rc0402jr-070rl/res-0r0-5-0-0625w-0402-thick-film/dp/9232516There is a black one as well.You can see it in the picture (more or less) in vertical position (as seen on the photo) in the middle, beneath the black wire, coming from the bottom, with an indication 'M6' (not visible on the image due to reflection) .Not sure what to make of that.

author: Fraser
author_rank: Super Contributor
timestamp: November 03, 2021, 04:40:57 pm
content: In the first image, the reason I thought it was Murata is becasue the logo looks very similar. See attached.Ceramite tend to use a straight forward "CM" or "Cera Mite" marking.

author: TimFox
author_rank: Super Contributor
timestamp: November 03, 2021, 05:17:48 pm
content: I stand corrected: I checked my stash of Ceramite leaded disc ceramic capacitors, and they have the straight "CM" marking shown in your photos.I didn't have any Murata parts handy to compare the logos.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 05:26:38 pm
content: Quote from: Fraser on November 03, 2021, 04:40:57 pmYes, I looked it up, and you're right, they are confusingly similar in logo.Concerning the white and black elements on my PCB, they could be film resistors, the white probably zero ohm, probably but not sure, and the black M6 or 6M, probably a 'shunt'. I have the impression, with the opamp and all, that this is some kind of 'current sensing' circuit. That could correspond with the fact of the light reading and ampmeter.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 05:31:18 pm
content: Quote from: TimFox on November 03, 2021, 05:17:48 pmYes, the logos are deceivingly alike. If Murata is Japanese that would make sense with Pentax of course.And they have all sorts of electronic components, not only capacitors. So maybe all the components in this device, but the opamp (from Intersil) are from Murata?

author: Chris_D
author_rank: Regular Contributor
timestamp: November 03, 2021, 05:45:03 pm
content: Quote from: Fraser on November 03, 2021, 04:40:57 pmAbout the calibration of the spotmeter and the diagram:I believe the diagram is from the earlier model, the 1°/21°.I know it, but this model is rather different from the later Pentax Spotmeter V (which was the last 'analog' model before the digital spotmeter.)For instance, it has two power sources (a 9V and a 1.3 V battery) instead of one (4.5V) , and the light reading has different circuits for low light and bright light reading, depending on the two batteries (I forgot for the moment which one powers the low and the bright light).Also the light meter scale that you see in the lens is not unified (the values of the low lights are below the scale, the values of the bright lights above).The Pentax spotmeter V has an unified scale, all the values are one the same level on the scale.And it is clear that the Spotmeter V is also more sophiscated in circuit design, with the opamp and the transistors, clearly missing from the earlier versions.

author: Fraser
author_rank: Super Contributor
timestamp: November 03, 2021, 10:34:14 pm
content: Chris_D,Yes I realised this after I posted the schematics and so deleted that post as it was just confusing mattersFraser

author: Chris_D
author_rank: Regular Contributor
timestamp: November 04, 2021, 04:50:02 am
content: Quote from: Fraser on November 03, 2021, 10:34:14 pmNo problem, I deeply appreciate it that you want to help me out.And of course, the basic principle is the same of both circuits, the ammeter and the switches are the same.I also lack the knowledge so I can't figure it out for myself that is also the problem here.But I learn every day something new thanks to this forum and its nice members.

author: vk6zgo
author_rank: Super Contributor
timestamp: November 04, 2021, 10:29:34 am
content: Quote from: Zero999 on November 03, 2021, 12:29:47 pmDon't be so sure-------- the resistor in a similar package that I mentioned was, from memory, in early 1980s equipment made by Sony.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 04, 2021, 11:02:35 am
content: Hello, thank you for the remark.Although I first thought as well that is was a resistor, it is very likely, according to the text on it, a capacitor, made by Murata.I'm checking it out with Murata itself for the moment, but it seems very likely.However, I have in the same device, something that looks like a capacitor and is very likely a resistor, so you remark is interesting in this respect.And perhaps this element I could unsolder and measure, it doesn't affect to much in the circuit I suppose (in the case it shouldn't survive the unsoldering)

author: Fraser
author_rank: Super Contributor
timestamp: November 04, 2021, 12:38:46 pm
content: Chris_D,Please will you upload some pictures of the whole PCB so that I may see the context of the components used in the design. Clear pictures of both sides of the PCB may help me in assisting you. If you can also state which wires from the PCB go to which ‘off board’ components such as the battery, meter, switches etc. In PCB reverse engineering I often come across components that are not easily identified by their part number. It is then Ca case of looking at the reverse engineered schematic to determine the components function and assess it’s likely effect if failed.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: November 04, 2021, 12:47:38 pm
content: I just saw your other thread relating to the ICL op-amp.If you upload your schematic diagram, no matter how rough it currently is, we can gain a lot of information from it. Just mark your mystery components with a question mark.In cases such as this, forum members need as much information as possible about the ‘patient’ as it is challenging to assist others remotely.Fraser

author: Chris_D
author_rank: Regular Contributor
timestamp: November 04, 2021, 02:59:55 pm
content: Hello,That is very kind.My drawing is more copying the PCB's than a real schematic diagram*, so I don't know if this can help as well but anyhow, I will post it as soon as I've finished ,I will accompany it with some pictures and comment.I'm currently looking into the last PCB (there are 3 PCB's interacting with each other) and I also need to figure out the right route of the wires to the PCB's and the switches.It can still take a couple of days if that's ok.*Concerning the 'largest' PCB (in reality quite small), it is difficult to photograph it in a whole, because it is still attached and beneath the lens in an difficult angle. Also the reason why I resorted to drawing it.

author: Chris_D
author_rank: Regular Contributor
timestamp: November 04, 2021, 03:02:03 pm
content: Quote from: Fraser on November 04, 2021, 12:38:46 pmOk, see my other (previous, in case my replies got mixed up) reply as well. Thanks a lot!