Hey, learning as I go here. Can all transistors be tested the same. When I am looking at the bias stabilizer transistors (2sc1384) I get a reading of 592 from B to E and 770 from E to B. All the other transistors in main board test open and 600 roughly.
Using your digital meter and measuring a 2SC1384 --when OUT of circuit in relation to the base when testing =base to emitter + emitter to base when you REVERSE the probes -IE a reading in BOTH direction relevant to the base then that BJT is faulty .
I have a feeling you haven't done this ?
One direction should give a reading and the other open circuit when you reverse the leads in relation to the base.
Of course an analogue multimeter is the opposite way around to a digital one when testing transistors (BJT ) .
I have a feeling you haven't done this ?
One direction should give a reading and the other open circuit when you reverse the leads in relation to the base.
Of course an analogue multimeter is the opposite way around to a digital one when testing transistors (BJT ) .
It is still in circuit, all the other transistors I checked in circuit gave positive reading, these two have not.
Best check is out of circuit with DMM transistor Hfe tester.
I have seen a transistor test ok with diode check but only have Hfe of 1 !
I have seen a transistor test ok with diode check but only have Hfe of 1 !
Rather than buy a hfe tester, I do a Iceo test, particularly on suspect output transistors & drivers. Bad transistors may resist 2 v of a meter diode test. 12 v supply or greater, a wall transformer is fine, 47 k resistor, series, series a DVM ma scale. Plus to collector of npn, minus to emitter. Opposite for pnp. Base open. current =12 v/47k (or 18 v or whatever low current voltage of transformer is) transistor is bad. Current 2 or 3 microamps, transistor is good to that open circuit voltage. My 250 vceo MJ15024 were testing bad @ 12 v, no need to kill yourself with 250 VDC.
Counterfeit transistors that might be good to 60 or 100 v, you may have to test that high. Don't use 2 hands on voltage that high, one hand at a time.
Counterfeit transistors that might be good to 60 or 100 v, you may have to test that high. Don't use 2 hands on voltage that high, one hand at a time.
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The $1 meter my coworker bought from Harbor Freight, which has a hfe socket, caused us to spend 2 hours disassembling a pipe (organ) chamber to check a solenoid, and 2 hours reassembling it when it was good. It wasn't the battery. He'd owned the meter for years. He was the senior worker.
No more $6 meters for me.
I bought my most recent $30 DVM meters from farnell, & Klein. Neither has hfe. The $10 more autorange models have, which waste a **** lot of time switching ranges when I'm trying to measure 3 to 50 volt test points. **** dancing numbers! I could care less for the 200 mv scale, which always comes first, followed by the 2 v scale. My reaction time is 56 ms, why wait for this 800 ms junk to decide what to do?
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Mine works fine.
I tested it against a transistor matcher/curve tracer I designed and they were both spot on the same.
I tested it against a transistor matcher/curve tracer I designed and they were both spot on the same.
"Dancing numbers " ?
Yes I recognize that when I worked for BT ,while Digital meters have their points the ones I used courtesy of BT were useless for testing long lines as the RF pick up made the digital display look as if it was playing a tune.
I reverted back to an old school designed for BT analog AVO and that provided accurate testing .
Too dear for them nowadays but I still have my old AVO 8 MKV bought very cheaply from BT due to them "binning them " while switching over to digital testing from a central control.
Yes I recognize that when I worked for BT ,while Digital meters have their points the ones I used courtesy of BT were useless for testing long lines as the RF pick up made the digital display look as if it was playing a tune.
I reverted back to an old school designed for BT analog AVO and that provided accurate testing .
Too dear for them nowadays but I still have my old AVO 8 MKV bought very cheaply from BT due to them "binning them " while switching over to digital testing from a central control.