This year, KP EXR something Sony with the PS under the HV board. You
know the one, they continued the chassis line in the XBR line a bit
longer. I believe they are 2SC4582s, and they both checked good on the
ohmmeter. Of course a bipolar transistor is a three layer device, and
did check good as such. It just did not amplify.

A couple years ago I had a Hitachi or Toshiba HDTV that had never had
anything plugged into the "colorstream". The symptom was that there was
no red on component inputs. It was a bitch to troubleshoot even with
the print. I traced it to a regular bipolar transistor that also
checked just fine as a three layer device yet did not transist. In
fact, I didn't lift the base because it was an SMD and I erroneously
changed the IC that fed it !

These are times when a meter just won't work, you need to see the
difference between the B and E waveforms, look at that and the load and
know what the collector waveform should be. But even that wouldn't find
this.

So how many have run across this "It does not transist" ?.

JURB

wrote:

This year, KP EXR something Sony with the PS under the HV board. You
know the one, they continued the chassis line in the XBR line a bit
longer. I believe they are 2SC4582s, and they both checked good on the
ohmmeter. Of course a bipolar transistor is a three layer device, and
did check good as such. It just did not amplify.

A couple years ago I had a Hitachi or Toshiba HDTV that had never had
anything plugged into the "colorstream". The symptom was that there was
no red on component inputs. It was a bitch to troubleshoot even with
the print. I traced it to a regular bipolar transistor that also
checked just fine as a three layer device yet did not transist. In
fact, I didn't lift the base because it was an SMD and I erroneously
changed the IC that fed it !

These are times when a meter just won't work, you need to see the
difference between the B and E waveforms, look at that and the load and
know what the collector waveform should be. But even that wouldn't find
this.

So how many have run across this "It does not transist" ?.

JURB

I expect most of us have. This is handled simply by using ac and a
logic gate to test trs with instead of or as well as a dc test. You
should see switched current waveform on the collector, the idea of the
logic is if i flows when it shouldnt, you get a fail reading. The logic
only passes the tr when i b gives i c and no i b gives no i c.


NT