EEVblog Electronics Community Forum
Electronics => Repair => Topic started by: hyteqsolutions on May 23, 2015, 04:19:43 am
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Good Afternoon EEVBlog,
A tad stuck on this one.
B1560 51Y (pnp) Epitaxial Transistor (7 of them)
&
D2390 51Y (npn) triple diffused planar transistor (7 of them)
Used in a Denon AVR-1905 amp.
I have tested both transistors the usual way with my auto-range multimeter. Black to middle or Red to middle etc... I get flow as per usual, but when I swap leads and test the outside only with leads reversed again, I get flow, on all of them. I am assuming that this means bad.
The Denon unit will fire up (Green LED will blink 5 times, then Red thereafter) the moment the start up cycle hits 'receiver' bang, red LED thereafter. Tested the hell out of this board and replaced some blown caps. Same issue, tested these guys and cannot make headway with them.
Datasheet: http://www.slideshare.net/tedyshinoda/data-sheet-power-transistors-sanken (http://www.slideshare.net/tedyshinoda/data-sheet-power-transistors-sanken)
Thoughts?
Thank You,
- HyTeQ-Solutions.
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On darlingtons there can be a protection diode across the E and C pins, if it shorts the component is faulty and you will see continuity in either direction. If unsure remove the transistor from circuit and perform both a separate diode (if possible) and resistance test and record your results for each test EC CE BE EB BC CB and then it's a little easier to deduce whats happened.
Don't expect the base to be the middle pin either, look closely at the data sheet pinout and equivalent circuit so you know exactly which way your testing.
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Do you measure them in circuit? Also 2SB1560 and 2SD2390 base is a first pin, not in the middle. They are darlingtons too.