Out of spec transistor? Help with ID? (0/1)

M

Michael Kers

Guest
Hi,

Preamble
=====
A little project of mine is to fix an older HP 6284A power supply. I
have the schematics for it, and am working through part-by-part
looking for anything defective. I came across something that has me
stumped. The power supply was used surplus, and did not work (since
I've had it)

Questions:
======
1) For a transistor BE 0.812V seems out of spec, could this be
something other than a bipolar junction silicon device?
2) What manufacturer might have made this device?

Background
=======
This power supply has a display, and in the display driver circuit
there is a dual-transistor to-78 package device (metal can, 6 leads, 2
matched transistors).

According to the schematics, there should be an Agilent 1854-0229
(Analog Devices MAT02FH, dual BJT, silicon, NPN, diff amp). I have 2
of these agilent parts (the mystery meat should be the third part,
identical to the other two, but its not), and the BE breakdown voltage
is around 0.65V for both sides of both known devices. This oddball
device has a breakdown of 0.812V or so.

I'm measuring the 0.812V with a fluke multimeter that has a diode
testing tool on it.

The oddball has the markings K8721 4-221 on it, and 2 symbols: an
lower case "i" (clear) in box of black background, and a delta symbol
(see attachment). I've tried every cross-reference I can (NEC, NTE,
ECG, Fairchild, intersil, google) but this part doesn't seem to exist
(?!?).



Thanks,
Mike
 
"Michael Kers" <majikdude@ab.telus.net> wrote in message
news:0i44f0lopiu01kb48vk26h9158kt1o1aug@4ax.com...
Hi,

Preamble
=====
A little project of mine is to fix an older HP 6284A power supply. I
have the schematics for it, and am working through part-by-part
looking for anything defective. I came across something that has me
stumped. The power supply was used surplus, and did not work (since
I've had it)

Questions:
======
1) For a transistor BE 0.812V seems out of spec, could this be
something other than a bipolar junction silicon device?
2) What manufacturer might have made this device?

Background
=======
This power supply has a display, and in the display driver circuit
there is a dual-transistor to-78 package device (metal can, 6 leads, 2
matched transistors).

According to the schematics, there should be an Agilent 1854-0229
(Analog Devices MAT02FH, dual BJT, silicon, NPN, diff amp). I have 2
of these agilent parts (the mystery meat should be the third part,
identical to the other two, but its not), and the BE breakdown voltage
is around 0.65V for both sides of both known devices. This oddball
device has a breakdown of 0.812V or so.

I'm measuring the 0.812V with a fluke multimeter that has a diode
testing tool on it.

The oddball has the markings K8721 4-221 on it, and 2 symbols: an
lower case "i" (clear) in box of black background, and a delta symbol
(see attachment). I've tried every cross-reference I can (NEC, NTE,
ECG, Fairchild, intersil, google) but this part doesn't seem to exist
(?!?).
Click to expand...
I've read and reread your multiple posts and I'm still not sure what
you're asking. Is this part bad? If not, then what's the problem?
There are HP parts references online.


Thanks,
Mike
Click to expand...
 
I've read and reread your multiple posts and I'm still not sure what
you're asking. Is this part bad? If not, then what's the problem?
There are HP parts references online.
Click to expand...
I apologize for the multiple posts. I should know better. I just got
a message post failed, so I erroneously retried before checking if it
actually made it. Won't happen again.

I'm asking for experience of others: Is a SI type transistor out of
spec around 0.8V? I know of ones that go as low as 0.5V on the BE and
are still fine, can it go the other way also? I can't say myself,
because I've never seen one past 0.7V on the BE, so my experience
(limited) says its toast.

Since I don't know what this part is (I have not been able to find any
reference sheets ANYWHERE) I'm not sure if its in spec or not. Hence
the query about experience of others. When I run out of hard cold
facts, I head for heuristics.

Mike

On Sun, 11 Jul 2004 21:48:40 -0700, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

"Michael Kers" <majikdude@ab.telus.net> wrote in message
news:0i44f0lopiu01kb48vk26h9158kt1o1aug@4ax.com...
Hi,

Preamble
=====
A little project of mine is to fix an older HP 6284A power supply. I
have the schematics for it, and am working through part-by-part
looking for anything defective. I came across something that has me
stumped. The power supply was used surplus, and did not work (since
I've had it)

Questions:
======
1) For a transistor BE 0.812V seems out of spec, could this be
something other than a bipolar junction silicon device?
2) What manufacturer might have made this device?

Background
=======
This power supply has a display, and in the display driver circuit
there is a dual-transistor to-78 package device (metal can, 6 leads, 2
matched transistors).

According to the schematics, there should be an Agilent 1854-0229
(Analog Devices MAT02FH, dual BJT, silicon, NPN, diff amp). I have 2
of these agilent parts (the mystery meat should be the third part,
identical to the other two, but its not), and the BE breakdown voltage
is around 0.65V for both sides of both known devices. This oddball
device has a breakdown of 0.812V or so.

I'm measuring the 0.812V with a fluke multimeter that has a diode
testing tool on it.

The oddball has the markings K8721 4-221 on it, and 2 symbols: an
lower case "i" (clear) in box of black background, and a delta symbol
(see attachment). I've tried every cross-reference I can (NEC, NTE,
ECG, Fairchild, intersil, google) but this part doesn't seem to exist
(?!?).



Thanks,
Mike
Click to expand...
 
I've read and reread your multiple posts and I'm still not sure what
Click to expand...
Hey, at least I didn't cross-post. I know enough not to do that.




On Sun, 11 Jul 2004 21:48:40 -0700, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:

"Michael Kers" <majikdude@ab.telus.net> wrote in message
news:0i44f0lopiu01kb48vk26h9158kt1o1aug@4ax.com...
Hi,

Preamble
=====
A little project of mine is to fix an older HP 6284A power supply. I
have the schematics for it, and am working through part-by-part
looking for anything defective. I came across something that has me
stumped. The power supply was used surplus, and did not work (since
I've had it)

Questions:
======
1) For a transistor BE 0.812V seems out of spec, could this be
something other than a bipolar junction silicon device?
2) What manufacturer might have made this device?

Background
=======
This power supply has a display, and in the display driver circuit
there is a dual-transistor to-78 package device (metal can, 6 leads, 2
matched transistors).

According to the schematics, there should be an Agilent 1854-0229
(Analog Devices MAT02FH, dual BJT, silicon, NPN, diff amp). I have 2
of these agilent parts (the mystery meat should be the third part,
identical to the other two, but its not), and the BE breakdown voltage
is around 0.65V for both sides of both known devices. This oddball
device has a breakdown of 0.812V or so.

I'm measuring the 0.812V with a fluke multimeter that has a diode
testing tool on it.

The oddball has the markings K8721 4-221 on it, and 2 symbols: an
lower case "i" (clear) in box of black background, and a delta symbol
(see attachment). I've tried every cross-reference I can (NEC, NTE,
ECG, Fairchild, intersil, google) but this part doesn't seem to exist
(?!?).

I've read and reread your multiple posts and I'm still not sure what
you're asking. Is this part bad? If not, then what's the problem?
There are HP parts references online.


Thanks,
Mike
Click to expand...
 
"Michael Kers" <majikdude@ab.telus.net> wrote in message
news:emk9f0hhqtsncrm6c6g07a7k5kjojge832@4ax.com...
I've read and reread your multiple posts and I'm still not sure what
you're asking. Is this part bad? If not, then what's the problem?
There are HP parts references online.

I apologize for the multiple posts. I should know better. I just got
a message post failed, so I erroneously retried before checking if it
actually made it. Won't happen again.

I'm asking for experience of others: Is a SI type transistor out of
spec around 0.8V? I know of ones that go as low as 0.5V on the BE and
are still fine, can it go the other way also? I can't say myself,
because I've never seen one past 0.7V on the BE, so my experience
(limited) says its toast.

Since I don't know what this part is (I have not been able to find any
reference sheets ANYWHERE) I'm not sure if its in spec or not. Hence
the query about experience of others. When I run out of hard cold
facts, I head for heuristics.
Click to expand...
Depends on how much current is going thru the transistor. If the
current is high, there needs to be a lot of base current to turn the
transistor fully on. The B-E voltage may go above 1 volt when the
transistor is saturated. Read the specs and it will tell you what the
Vbe(sat) is.


Mike

On Sun, 11 Jul 2004 21:48:40 -0700, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:


"Michael Kers" <majikdude@ab.telus.net> wrote in message
news:0i44f0lopiu01kb48vk26h9158kt1o1aug@4ax.com...
Hi,

Preamble
=====
A little project of mine is to fix an older HP 6284A power supply.
I
have the schematics for it, and am working through part-by-part
looking for anything defective. I came across something that has
me
stumped. The power supply was used surplus, and did not work (since
I've had it)

Questions:
======
1) For a transistor BE 0.812V seems out of spec, could this be
something other than a bipolar junction silicon device?
2) What manufacturer might have made this device?

Background
=======
This power supply has a display, and in the display driver circuit
there is a dual-transistor to-78 package device (metal can, 6
leads, 2
matched transistors).

According to the schematics, there should be an Agilent 1854-0229
(Analog Devices MAT02FH, dual BJT, silicon, NPN, diff amp). I have
2
of these agilent parts (the mystery meat should be the third part,
identical to the other two, but its not), and the BE breakdown
voltage
is around 0.65V for both sides of both known devices. This oddball
device has a breakdown of 0.812V or so.

I'm measuring the 0.812V with a fluke multimeter that has a diode
testing tool on it.

The oddball has the markings K8721 4-221 on it, and 2 symbols: an
lower case "i" (clear) in box of black background, and a delta
symbol
(see attachment). I've tried every cross-reference I can (NEC, NTE,
ECG, Fairchild, intersil, google) but this part doesn't seem to
exist
(?!?).



Thanks,
Mike
Click to expand...
 
"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com>
wrote in message news:10fcs0eosrspc26@corp.supernews.com...
"Michael Kers" <majikdude@ab.telus.net> wrote in message
news:emk9f0hhqtsncrm6c6g07a7k5kjojge832@4ax.com...
I've read and reread your multiple posts and I'm still not sure
what
you're asking. Is this part bad? If not, then what's the problem?
There are HP parts references online.

I apologize for the multiple posts. I should know better. I just
got
a message post failed, so I erroneously retried before checking if
it
actually made it. Won't happen again.

I'm asking for experience of others: Is a SI type transistor out of
spec around 0.8V? I know of ones that go as low as 0.5V on the BE
and
are still fine, can it go the other way also? I can't say myself,
because I've never seen one past 0.7V on the BE, so my experience
(limited) says its toast.

Since I don't know what this part is (I have not been able to find
any
reference sheets ANYWHERE) I'm not sure if its in spec or not.
Hence
the query about experience of others. When I run out of hard cold
facts, I head for heuristics.

Depends on how much current is going thru the transistor. If the
current is high, there needs to be a lot of base current to turn the
transistor fully on. The B-E voltage may go above 1 volt when the
transistor is saturated. Read the specs and it will tell you what the
Vbe(sat) is.
Click to expand...
I forgot to mention that the guys in sci.electronics.repair have a good
feel for this kind of thing, so ask this question there.


Mike

On Sun, 11 Jul 2004 21:48:40 -0700, "Watson A.Name - \"Watt Sun, the
Dark Remover\"" <NOSPAM@dslextreme.com> wrote:


"Michael Kers" <majikdude@ab.telus.net> wrote in message
news:0i44f0lopiu01kb48vk26h9158kt1o1aug@4ax.com...
Hi,

Preamble
=====
A little project of mine is to fix an older HP 6284A power
supply.
I
have the schematics for it, and am working through part-by-part
looking for anything defective. I came across something that has
me
stumped. The power supply was used surplus, and did not work
(since
I've had it)

Questions:
======
1) For a transistor BE 0.812V seems out of spec, could this be
something other than a bipolar junction silicon device?
2) What manufacturer might have made this device?

Background
=======
This power supply has a display, and in the display driver
circuit
there is a dual-transistor to-78 package device (metal can, 6
leads, 2
matched transistors).

According to the schematics, there should be an Agilent 1854-0229
(Analog Devices MAT02FH, dual BJT, silicon, NPN, diff amp). I
have
2
of these agilent parts (the mystery meat should be the third
part,
identical to the other two, but its not), and the BE breakdown
voltage
is around 0.65V for both sides of both known devices. This
oddball
device has a breakdown of 0.812V or so.

I'm measuring the 0.812V with a fluke multimeter that has a diode
testing tool on it.

The oddball has the markings K8721 4-221 on it, and 2 symbols: an
lower case "i" (clear) in box of black background, and a delta
symbol
(see attachment). I've tried every cross-reference I can (NEC,
NTE,
ECG, Fairchild, intersil, google) but this part doesn't seem to
exist
(?!?).



Thanks,
Mike
Click to expand...
 
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