Author Topic: Help identify glass encapsulated diodes  (Read 2364 times)

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Offline fzabkar

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Re: Help identify glass encapsulated diodes
« Reply #25 on: August 26, 2024, 06:19:27 pm »
You can have some confidence in your decoding of the part markings if the datasheets for Q23 and Q24 indicate that they are complementary PNP and NPN BJTs.
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #26 on: August 26, 2024, 06:20:30 pm »
That's the problem with surface mount components. XL can mean many things.
(I'm sorry that the code Q23 misled you, and I sincerely apologize again!) Yes, it's strange that when I removed XL from the circuit board, the diode characteristics between pins 1 and 2 still fluctuated like 0.06-0.08. But when I measured them again after a while, they changed to 0.300-0.500 occasionally, which is a strange phenomenon. I searched everywhere, and only 2SD2704K meets the criteria. I have already ordered it, and I will not rashly install them on the circuit board until I am completely sure that 2SD2704K is the correct model. Acting rashly will only lead to the expansion of the malfunction, which is not what I want to see!
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #27 on: August 26, 2024, 06:24:58 pm »
You can have some confidence in your decoding of the part markings if the datasheets for Q23 and Q24 indicate that they are complementary PNP and NPN BJTs.
You can take a look at my other latest reply messages. I am very sorry for the inconvenience caused by the code Q23. The component of the silk screen XL is not included in the circuit diagram I provided, it is located elsewhere. I haven't found any problems with the circuit around LT1007 so far. I won't find any problems here for the time being. I will go to other places to seek the fault phenomenon, such as this XL screen printed switch transistor calibrated with Q!
 

Offline Kim Christensen

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Re: Help identify glass encapsulated diodes
« Reply #28 on: August 26, 2024, 06:29:24 pm »
Hmmm... It could be a MOSFET. If you leave the gate floating and do a diode check between drain and source, you will get readings that drift. Shorting the gate to the source will make the drain-source measure open, or as a diode if measured in reverse.
« Last Edit: August 26, 2024, 06:31:07 pm by Kim Christensen »
 

Offline fzabkar

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Re: Help identify glass encapsulated diodes
« Reply #29 on: August 26, 2024, 06:40:20 pm »
The mark might be "KL" ...
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #30 on: August 26, 2024, 06:44:35 pm »
The mark might be "KL" ...
There are many components in the circuit that are silk screened as XL. Based on most of the others, I prefer XL. What do you think?
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #31 on: August 26, 2024, 06:59:01 pm »
Hmmm... It could be a MOSFET. If you leave the gate floating and do a diode check between drain and source, you will get readings that drift. Shorting the gate to the source will make the drain-source measure open, or as a diode if measured in reverse.
Because I am currently unable to determine the specific pin situation, and I am also unsure if it is functioning properly. Assuming the pin arrangement is as shown in the attached diagram, it will help me explain. When I put the red pen on foot 3 and the black pen on foot 1 or 2, both display a pressure drop of 0.698. Placing the probe in reverse is OL. Another type of measurement is the black probe 1 or 2 and the red probe 1 or 2. The multimeter gave me feedback on a very strange state, constantly flashing, and I couldn't even see its changes, probably flashing back and forth between 2.000-1.9-1.8 and gradually decreasing open.
 

Offline fzabkar

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Re: Help identify glass encapsulated diodes
« Reply #32 on: August 26, 2024, 07:10:16 pm »
The stylised "C3" marking appears to be Toshiba's, if this supplier is to be believed:

https://www.mscnelectronics.com/home/produto/codigo:12213/smd-di-1ss226-100ma-80v-ultra-high-speed-switching-diodes-diodo-smt

https://www.mscnelectronics.com/upload/Produto12213.grande.71aef49d58c5126b7c1e49ac865f47b1.jpg

Therefore, I would look for an "XL" or "KL" part by Toshiba.

My advice is to try to view the circuit as functional blocks instead of testing each individual component.

For example, the previous circuit could be seen as the following:

https://handwiki.org/wiki/images/7/7f/Pushpull_%28English%29.png

All you would need to do to verify that circuit would be to vary the input to the op-amp above and below ground (by operating the appliance/device), and then observe the output at the junction of the two current sense resistors.
« Last Edit: August 26, 2024, 07:14:20 pm by fzabkar »
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #33 on: August 26, 2024, 07:18:57 pm »
The stylised "C3" marking appears to be Toshiba's, if this supplier is to be believed:

https://www.mscnelectronics.com/home/produto/codigo:12213/smd-di-1ss226-100ma-80v-ultra-high-speed-switching-diodes-diodo-smt

https://www.mscnelectronics.com/upload/Produto12213.grande.71aef49d58c5126b7c1e49ac865f47b1.jpg

Therefore, I would look for an "XL" or "KL" part by Toshiba.

My advice is to try to view the circuit as functional blocks instead of testing each individual component.

For example, the previous circuit could be seen as the following:

https://handwiki.org/wiki/images/7/7f/Pushpull_%28English%29.png

All you would need to do to verify that circuit would be to vary the input to the op-amp above and below ground (by operating the appliance/device), and then observe the output at the junction of the two current sense resistors.
You are simply a genius. Based on your ideas, I have retrieved its true model. 2SK209-BL, I will carefully inspect its quality next! Thank you.
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #34 on: August 26, 2024, 07:33:56 pm »

My advice is to try to view the circuit as functional blocks instead of testing each individual component.

For example, the previous circuit could be seen as the following:

https://handwiki.org/wiki/images/7/7f/Pushpull_%28English%29.png

All you would need to do to verify that circuit would be to vary the input to the op-amp above and below ground (by operating the appliance/device), and then observe the output at the junction of the two current sense resistors.
[/quote]I cannot distinguish where the frequency comes from with my ability, so I can only search aimlessly. In fact, I found some useful things. The arrow above the figure points to the signal generated by the frequency from the muc, which is exactly the same as the frequency I set. I found the HC4053BF on the back of the line, and it finally went to its 10 legs, but there is only a 0/1 high and low level. I don't know what this means. After entering pin 10 of HC4053BF, the frequency never came out again
 

Offline fzabkar

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Re: Help identify glass encapsulated diodes
« Reply #35 on: August 26, 2024, 07:46:55 pm »
U18 consists of 3 SPDT analogue switches. Pin #10 is a control input. A high or low on this pin connects pin #15 to either of pin #1 or pin #2.

https://www.mouser.com/datasheet/2/916/74HC_HCT4053-1541743.pdf
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #36 on: August 26, 2024, 07:55:35 pm »
U18 consists of 3 SPDT analogue switches. Pin #10 is a control input. A high or low on this pin connects pin #15 to either of pin #1 or pin #2.

https://www.mouser.com/datasheet/2/916/74HC_HCT4053-1541743.pdf
I understand this, but what I don't understand is that the set frequency is generated by the MCU. Why did it end up here instead of going to the output terminal? If I set the frequency to 100Hz, then this 10 pin will display 100Hz very stably. I am very puzzled about this... and assuming XL is a field effect transistor model 2sk209 bl, what is the purpose of directly short circuiting the source and drain of pin 1 and pin 2?
 

Offline Kim Christensen

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Re: Help identify glass encapsulated diodes
« Reply #37 on: August 26, 2024, 08:18:06 pm »
Perhaps they are using it as some sort of crude, or ingenious, DAC.

Just a guess and probably not how it's designed:
If you wanted to generate a square-wave that swung between 1V and 3.5V you could feed these two DC voltages into pins 1 & 2, and get a square-wave out on pin 15 that toggles between 1V and 3.5V at the same frequency as the logic level signal on pin 10.
If the 1V and 4.5V were missing (at zero V) then that would explain why the "signal" at pin 10 seems to go nowhere. Or, if pin 6 (INHibit) is at logic high, then all analog switches would be disabled with the same result.
 

Offline fzabkar

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Re: Help identify glass encapsulated diodes
« Reply #38 on: August 26, 2024, 08:28:13 pm »
U15 and U16 (?) appear to be 4053BF ICs. U18 looks different. :-?

https://docs.rs-online.com/8004/0900766b8082f4fe.pdf (Toshiba TC4053BP / BF / BFT)
« Last Edit: August 26, 2024, 08:33:38 pm by fzabkar »
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #39 on: August 26, 2024, 08:30:55 pm »
Perhaps they are using it as some sort of crude, or ingenious, DAC.

Just a guess and probably not how it's designed:
If you wanted to generate a square-wave that swung between 1V and 3.5V you could feed these two DC voltages into pins 1 & 2, and get a square-wave out on pin 15 that toggles between 1V and 3.5V at the same frequency as the logic level signal on pin 10.
If the 1V and 4.5V were missing (at zero V) then that would explain why the "signal" at pin 10 seems to go nowhere. Or, if pin 6 (INHibit) is at logic high, then all analog switches would be disabled with the same result.
I have been thinking about whether pin10 can output the correct frequency from pin15, because this signal has no way out unless it encounters an unfortunate disconnection. After listening to your answer, I realized that pin1 and pin2 still need to cooperate, so I will follow them. Don't worry, pin6 is always in a low level state. I vaguely remember testing pin1 and pin2 with a multimeter before, and they both had no voltage, only a weak mv. Also, I just discovered an interesting phenomenon. If I touch both pin1 and pin2 of the LT1012 operational amplifier at the same time, the output port will display the frequency value I set correctly! And both LT1012 can
 

Offline 晓看风云Topic starter

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Re: Help identify glass encapsulated diodes
« Reply #40 on: August 26, 2024, 08:35:10 pm »
U15 and U16 (?) appear to be 4053BF ICs. U18 looks different. :-?
U18 is CD4052G, analog multiplexer. Please follow my latest reply. An interesting phenomenon... I have already put XL back on the circuit board because I tried another XL and they performed the same. I am a bit reluctant to believe that there may be as many as 8 faults on the circuit board at the same time.
 


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