"John Clayton" wrote in message
...
This TV came with a set of mini-manual schematics.
I troubleshot a +130 V problem to the horizontal output transister.
Flameproof resisters R1706 & R1707 kept frying. When Q1702 was removed
from
the circuit, everything was fine and the 130v fuse would not blow anymore.

My problem is that the Horiz. Output xsister has "Japan 1881" stamped on
it.
The parts list shows a GE part number but I can not get that anymore.
Their
part number (EP15X127) does not cross to an NTE number.

It is Japanese, so I figured the real number must be 2SD1881, sine it is
an
AF application transister and NPN.
2SD1881 does cross to an NTE2353 and the NTE device is a Horizontal output
transister. it Collector-emitter voltage is rated at 1500volts which is
the
same rating as the capacitor (C1702) that is in parallel with c-e of
Q1702.

However, the NTE device has an internal damping diode that does not show
up
on the schematic (they may have just not shown it, I know) and it is the
wrong case style of the transister I am replacing. I forget case style
naming conventions but the faulty transister is a teardrop shape with only
the emitter and base leads protruding from the bottom, the case being the
collector and has a flat mica insulator between it and the chassis of the
TV/circuit board.

My question, How can I be sure that, even if I can find an NTE device with
the correct case style and specs, that I need the internal diode or not?

Also, from searching on the internet, it seems that a 2SD1881 is a very
common transister for this application. Does anyone know of a part number
I
can readily find that is a suitable substitute and the same case style as
I
have now?

I suppose I can use the NTE2353 in it's case style configuration, but to
ensure proper heat dissipation it would require a bit of modification and
I
am concerned about high-voltage arcing.

Any help would be greatly appreciated.

Here is the schematic:


That transistor is a T03 case style. There is one NTE,
NTE89 which is a T03 horizontal output transistor, max. collector curent 6
amps, collector to base volts 1500, collector to emitter 600 volts,emitter
to base 5 volts, typical hFE 400 min., power dissipation 50 watts. This
would probably replace the EP15X127, but it does have an internal damper
diode. If the one in the GE does not have an internal damper, there will be
an external one, from collector to ground or to emitter. Just remove that
one if you use the NTE89.

"Malcolm Blackard" bravely wrote to "All" (24 May 04 15:58:45)
--- on the heady topic of " GE 40PW3000K TV Horiz. Output xsister question"

MB From: "Malcolm Blackard"

MB "John Clayton" wrote in message
MB ...
This TV came with a set of mini-manual schematics.
I troubleshot a +130 V problem to the horizontal output transister.
Flameproof resisters R1706 & R1707 kept frying. When Q1702 was removed
from
the circuit, everything was fine and the 130v fuse would not blow anymore.

My problem is that the Horiz. Output xsister has "Japan 1881" stamped on
it.
The parts list shows a GE part number but I can not get that anymore.
MB Their
part number (EP15X127) does not cross to an NTE number.

It is Japanese, so I figured the real number must be 2SD1881, sine it is
an
AF application transister and NPN.
2SD1881 does cross to an NTE2353 and the NTE device is a Horizontal output
transister. it Collector-emitter voltage is rated at 1500volts which is
the
same rating as the capacitor (C1702) that is in parallel with c-e of
MB Q1702.

However, the NTE device has an internal damping diode that does not show
up
on the schematic (they may have just not shown it, I know) and it is the
wrong case style of the transister I am replacing. I forget case style
naming conventions but the faulty transister is a teardrop shape with only
the emitter and base leads protruding from the bottom, the case being the
collector and has a flat mica insulator between it and the chassis of the
TV/circuit board.

My question, How can I be sure that, even if I can find an NTE device with
the correct case style and specs, that I need the internal diode or not?

Also, from searching on the internet, it seems that a 2SD1881 is a very
common transister for this application. Does anyone know of a part number
I
can readily find that is a suitable substitute and the same case style as
I
have now?

I suppose I can use the NTE2353 in it's case style configuration, but to
ensure proper heat dissipation it would require a bit of modification and
I
am concerned about high-voltage arcing.

Any help would be greatly appreciated.

Here is the schematic:


That transistor is a T03 case style. There is one NTE,
MB NTE89 which is a T03 horizontal output transistor, max. collector
MB curent 6 amps, collector to base volts 1500, collector to emitter 600
MB volts,emitter to base 5 volts, typical hFE 400 min., power dissipation
MB 50 watts. This would probably replace the EP15X127, but it does have an
MB internal damper diode. If the one in the GE does not have an internal
MB damper, there will be an external one, from collector to ground or to
MB emitter. Just remove that one if you use the NTE89.


It usually doesn't matter if there are 2 damper diodes in parallel.
The main difference is if there exists a Ferrite Bead in the emitter
leg. For a transistor without diode this means the FB will stop RFI
from the transistor only. However the external diode will often have
its own. For a transistor with a diode the FB will stop RFI from both.

However, an exception is if the external damper is used to generate a
deflection circuit offset. In this less common case an internal damper
will definitely cause a problem by disabling this function.

Asimov
******

.... Of course it's grounded! ...watch, ...YEEEEEAAAAAAAAHHHHHHHH!!!!