SKA6516: Difference between revisions

Jump to navigation Jump to search
no edit summary
(Added some curve traces for the 151-0367-00 showcasing the parasitic reverse diode junction.)
No edit summary
Line 10: Line 10:
{{MissingSpecs}}
{{MissingSpecs}}


[[User:Zenwizard|Zenwizard Studios]] found thirteen of these in a [[475]] and thirteen of those tested as having a parasitic reverse diode junction; a curve trace of the 151-0367-00 exhibiting a low reverse breakdown voltage can be seen in the images.
[[User:Zenwizard|Zenwizard Studios]] found thirteen of these in a [[475]] and showed that thirteen of those tested as "having a parasitic reverse diode junction" on a cheap component tester.
''There is no such diode, parasitic or not'' – the cheap tester displays this symbol when the DUT has a low reverse breakdown voltage as seen in the traces below.
See the thread at https://groups.io/g/TekScopes/topic/101335545#201002''.


A list of eighteen has been extracted from the [[Media:Tektronix_475_Oscilloscope_Service_Manual.pdf|Service Manual]] and is shared on the [[475/Repairs#Problematic Transistors|475 Repairs]] page.
Since reverse breakdown can damage the DUT, small-signal RF transistors should not be tested on component testers that may trigger that breakdown. They should be checked only on a curve tracer.


'''Suitable Modern Replacement'''
'''Suitable Modern Replacement'''


The 475 Service manual lists some of the transistors with alternatives, and some without - so I'd be careful to check that some need to be closer in spec than others.
The 475 Service manual lists some of the transistors with alternatives, and some without, i.e. some may need to be closer in spec than others.
A list of eighteen has been extracted from the [[Media:Tektronix_475_Oscilloscope_Service_Manual.pdf|Service Manual]] and is shared on the [[475/Repairs#Problematic Transistors|475 Repairs]] page.


In his [https://www.youtube.com/watch?v=gEXYRPNohyA video], Mr [[User:Zenwizard|ZenWizard Studios]] used [[Media:KSP10.pdf |Fairchild/On Semi KSP10BU]] from [https://eu.mouser.com/ProductDetail/onsemi-Fairchild/KSP10BU Mouser]. [https://uk.farnell.com/c/semiconductors-discretes/transistors/bipolar-transistors?st=ksp10&showResults=true Farnell] has them, too.
In his [https://www.youtube.com/watch?v=gEXYRPNohyA video], Mr [[User:Zenwizard|ZenWizard Studios]] used [[Media:KSP10.pdf |Fairchild/On Semi KSP10BU]] from [https://eu.mouser.com/ProductDetail/onsemi-Fairchild/KSP10BU Mouser]. [https://uk.farnell.com/c/semiconductors-discretes/transistors/bipolar-transistors?st=ksp10&showResults=true Farnell] has them, too.
Line 33: Line 36:
151-0367-00 Back.jpg
151-0367-00 Back.jpg
151-0367-00 Pile.jpg
151-0367-00 Pile.jpg
151-0367-00_curvetrace.jpg | Typical curve trace of 151-0367-00 in positive direction
151-0367-00_curvetrace.jpg       | Typical curve trace of 151-0367-00 in positive direction ''(Uploader - please add annotation of axes)''
151-0367-00_curvetrace_fault.jpg | Typical curve trace of 151-0367-00 in negative direction; the transistor has a low reverse bias breakdown voltage
151-0367-00_curvetrace_fault.jpg | Typical curve trace of 151-0367-00 in negative direction; the transistor has a low reverse bias breakdown voltage ''(Uploader - please add annotation of axes)''
2N3053_curvetrace.jpg | Typical reverse bias curve trace of a good 2N3053 transistor
2N3053_curvetrace.jpg           | Typical reverse bias curve trace of a good 2N3053 transistor (note this is a low-frequency power device with large junctions so it is not comparable to the 151-0367-00)
</gallery>
</gallery>


Navigation menu