EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: sr77 on January 27, 2020, 04:55:21 am
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Hello everybody, I’m trying to figure out what transistor i have so that i can find a datasheet and a replacement. The writing on it says:
M176
023
Any ideas? I appreciate the help.
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You've left out too much that you can see, but we can't. We've no clue if you're looking at a big quarter-sized power transistor, a tiny smd device the size of a gnat, or anything in-between. And for that matter, are you even sure it's a transistor? Is there any labeling on the circuit board? What's the nature of the device it's in? Approximately how old is it? (That tells us what vintage the components are.)
I'd suggest a picture might be the easiest way to convey that information.
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It’s a b&k precision 290 multimeter. I’m guessing it’s from the 70s.
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Looks like "Motorola" - so that "M" is not a part number.
Here is a look at the schematics (at 25:30):
https://youtu.be/A0PDHj1O02I (https://youtu.be/A0PDHj1O02I)
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https://elektrotanya.com/bk-precision_290_sollid_state_electronic_multimeter_instr._sm.zip/download.html
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Haven't looked at the schematic, would MPSA76 fit?
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I identified Q1 as SPS2306. (Found because of number 176-023-9-001)
Q2 is ddescribed as "blue dot", don´t know what that means.
Which is is Q1 or Q2 ?
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In the ‘good old days’ I saw different colour dots on transistors indicating gain ranges. So you sometimes needed to fit a transistor with the same gain range when looking for a replacement. In some cases you had to ‘select on test’ and actually test a whole bunch of the same part number to find one that had the correct gain value ! Oh those were the days ;D
Fraser
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Looks like "Motorola" - so that "M" is not a part number.
Here is a look at the schematics (at 25:30):
https://youtu.be/A0PDHj1O02I (https://youtu.be/A0PDHj1O02I)
According to that video, if the meter isn't working then be sure to check the bulb since it is wired in series with the the rest of the circuit. Apparently they are using the bulb as a current limiter.
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I identified Q1 as SPS2306. (Found because of number 176-023-9-001)
Q2 is ddescribed as "blue dot", don´t know what that means.
Which is is Q1 or Q2 ?
It's Q1.
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Haven't looked at the schematic, would MPSA76 fit?
The manual says "transistor silicon signal, NPN" followed by B&K part number 176-023-9-001.
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I identified Q1 as SPS2306. (Found because of number 176-023-9-001)
Q2 is ddescribed as "blue dot", don´t know what that means.
Which is is Q1 or Q2 ?
This is correct. See page 5 of this pdf: http://bee.mif.pg.gda.pl/ciasteczkowypotwor/B&K/501a.pdf (http://bee.mif.pg.gda.pl/ciasteczkowypotwor/B&K/501a.pdf)
This site (https://www.weisd.com/products/678370-sps2306-nte-equivalent-nte123ap-npn-audio-transisto (https://www.weisd.com/products/678370-sps2306-nte-equivalent-nte123ap-npn-audio-transisto)) lists it as equivalet to NTE123AP
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I just wanted to thank everyone for taking the time to help. Thanks and see you next time!