Jens Sch�nfeld wrote:
Hi list,
I know this is not a chip-related question, but it's semiconductors, so it's at least half on-topic.
I'm repairing my Hameg HM604 oscilloscope, it's not switching off the beam on backtrace and during wait-for-trigger. I checked transistors in the intensity control area (I have no schematics), and found one transistor with funny behaviour - I can measure three diodes, so I'm pretty sure this one is in silicon Nirwana.
The question I have is about the pinuot of this type, and how they marked the parts back then:
http://think42.com/bf311.jpg
Both these transistors come out of the oscilloscope. The right one behaves correctly, assuming that the base is the right pin (I can measure two diodes to that pin, and the other two have no connection in either direction, which is correct for TO92Z package). The left one has diodes between all pins (not shorts!), so I assume it's dead. The question is: Why has the TFK one (left on the picture) blue paint on top? Why did Hameg use different manufacturers for same-type transistors? There is no other transistor with blue marking on top, and it did not look like this one has been exchanged before (except someone did a *very* clean repair job). Is it some marking to distinguish between TO92 (CBE pinout) and TO92Z (ECB pinout)??
I did not find any reliable data using Google, only some places that say this type is obsolete. Any help in finding the right replacement is appreciated.
ciao,
According to my databook, the pinout is C E B reading from left to right in your photo.
Very unusual to find the centre pin as emitter!
25V Vce, 40 mA, Frequency when gain =1 = 375Mhz - That's high
Base capacitance 0R7 - very low.
As for blue paint, it could be the divice was tested, the device was selected, the board
was tested, the board was repaired, or some lady was messy with her nail varnish :-)
I wisah you well with it,
Declan Moriarty
-- Author: Declan Moriarty INET: [EMAIL PROTECTED]
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