I've identified a bad transistor in the power supply of an audio component,
circa 1981. It's a 2SB527 PNP transistor... I had a bit of a look around on
the net and didn't find any quick easy sources. This transistor's sole
function is to convert -26VDC coming off one side of a bridge rectifier
to -13 volts. It's wired up as follows, and I apologize for not being more
skilled in ascii art or I'd try to draw it.

The collector is the -26VDC input. It is connected to ground via a 100uF
cap.
The emitter is the -13VDC output. It is connected to ground via a 10uF cap.
The base is connected to a series 470-ohm resistor, then a parallel 10uF cap
(to ground), then a parallel zener diode (to ground), then a 5.6K-ohm
resistor, then to the collector.

My question is thus: if my downstream components can get by with -15VDC,
can I just substitute a 7915 15VDC negative voltage regulator? There are no
feedback connections from any other part of my circuit to this transistor,
it's output voltage should not vary under normal conditions. And, by freak
coincidence, the pinout of the regulator matches my circuit perfectly, it'd
be a straight swap and removing a couple of resistors. And perhaps most
importantly, I have one.

I'd think that any PNP power xistor with an adequate voltage rating would
do - this is just a pass xistor wired as an EF isn't it?

David

"Dave" wrote in message
news:%CVTf.6013$J43.2877@edtnps90...
I've identified a bad transistor in the power supply of an audio
component,
circa 1981. It's a 2SB527 PNP transistor... I had a bit of a look around
on
the net and didn't find any quick easy sources. This transistor's sole
function is to convert -26VDC coming off one side of a bridge rectifier
to -13 volts. [snip]

Dave wrote:
I've identified a bad transistor in the power supply of an audio
component, circa 1981. It's a 2SB527 PNP transistor... I had a bit
of a look around on the net and didn't find any quick easy sources.

Xref:
http://www.st.com/stonline/books/pdf/docs/4171.pdf

"David C. Partridge" wrote in message
...
I'd think that any PNP power xistor with an adequate voltage rating would
do - this is just a pass xistor wired as an EF isn't it?

David

I know very little of transistors other than their basic function, so I
don't know the answer to your question above.

As I noted, it's being used to (down)-regulate negative DC voltage. What
might the reason have been to opt for this transistor over a regulator?
There is a +5VDC regulator right next door in the same circuit.

Can I use the regulator in place of the transistor?

In article , "Travis Jordan" wrote:
Dave wrote:
I've identified a bad transistor in the power supply of an audio
component, circa 1981. It's a 2SB527 PNP transistor... I had a bit
of a look around on the net and didn't find any quick easy sources.

Xref:
http://www.st.com/stonline/books/pdf/docs/4171.pdf



2SB527 PS TO125 110 v 90v 5v 2A 10WT 50minHFE
Froms Towers Transistor Selector No freq. given.

There is also some crosses at
http://www.ee.washington.edu/circuit...rts/cross.html

Also my page.
http://www.pitt.edu/~szekeres/shopchip.htm

"Dave" wrote in message
news:EYVTf.6018$J43.3427@edtnps90...
"David C. Partridge" wrote in message
...
I'd think that any PNP power xistor with an adequate voltage rating would
do - this is just a pass xistor wired as an EF isn't it?

David

I know very little of transistors other than their basic function, so I
don't know the answer to your question above.

As I noted, it's being used to (down)-regulate negative DC voltage. What
might the reason have been to opt for this transistor over a regulator?
There is a +5VDC regulator right next door in the same circuit.

Can I use the regulator in place of the transistor?



Maybe, maybe not. The 2V difference probably isn't critical, but we don't
know how much current is being drawn. The 7815 is only good for around an
amp with a big heatsink, (some variants 1.5 A), the 2SB527 is good for 2A.
You could try one and measure the current, I doubt the current draw will be
anywhere near 2A. You'll probably want a decent heatsink though, and to get
closer to 13V you could bung 3 series diodes in the output of the regulator
output to give 15-2.1=12.9V. Take care to use diodes rated higher than the
current though, 1n400x might not be adequate. Again, they're only good for 1
Amp.

As for a replacement transistor, just about any power transistor of similar
(or better) rating and similar physical size will do, it isn't critical in
this application. You could use something in a TO220 package like a TIP42c
which is a popular transistor here in the UK.

http://www.fairchildsemi.com/ds/TI%2FTIP42C.pdf

Dave

If the base is being driven by a 13.6V zener and the collector has 26V, then
I'd expect a 13V output on the emitter.

---.--------.---------------------. -26V
| | |
| x |
| x 5k6 |
| x |
| | |/
= 100uF .-----.--xxxx--------|
| | | 470R |\
| V | |----- -13V
| ~ ZD = 10uF = 10uF
| | | |
---.--------.-----.----------------.----- 0V

If the above is about right then any PNP with a suitable rating should do,
and no you probably can't use the VR you have as -15V will probably be too
high for the following circuits.

Dave

"Dave" wrote in message
news:EYVTf.6018$J43.3427@edtnps90...
"David C. Partridge" wrote in message
...
I'd think that any PNP power xistor with an adequate voltage rating would
do - this is just a pass xistor wired as an EF isn't it?

David

I know very little of transistors other than their basic function, so I
don't know the answer to your question above.

As I noted, it's being used to (down)-regulate negative DC voltage. What
might the reason have been to opt for this transistor over a regulator?
There is a +5VDC regulator right next door in the same circuit.

Can I use the regulator in place of the transistor?

In article , (GregS) wrote:
In article , "Travis Jordan"
wrote:
Dave wrote:
I've identified a bad transistor in the power supply of an audio
component, circa 1981. It's a 2SB527 PNP transistor... I had a bit
of a look around on the net and didn't find any quick easy sources.

Xref:
http://www.st.com/stonline/books/pdf/docs/4171.pdf



2SB527 PS TO125 110 v 90v 5v 2A 10WT 50minHFE
Froms Towers Transistor Selector No freq. given.

There is also some crosses at
http://www.ee.washington.edu/circuit...rts/cross.html

Also my page.
http://www.pitt.edu/~szekeres/shopchip.htm

I forgot to list the USA/Euro equivalant, also in the Towers book.
2n5180 and Euro BD140


Type in BD140 in findchips.com

Most people would just use the NTEreplacement.
I found a distributor who claims to sell this Towers
International Transistor Selector from 1977 ??

greg

"GregS" wrote in message
...
In article , "Travis
Jordan" wrote:
Dave wrote:
I've identified a bad transistor in the power supply of an audio
component, circa 1981. It's a 2SB527 PNP transistor... I had a bit
of a look around on the net and didn't find any quick easy sources.

Xref:
http://www.st.com/stonline/books/pdf/docs/4171.pdf



2SB527 PS TO125 110 v 90v 5v 2A 10WT 50minHFE
Froms Towers Transistor Selector No freq. given.

That's odd... I am finding all over the place on the net:

2SB527 TO220 110V 100V 0A8 10W 50minHFE 300maxHFE

That's 800mA rated, not 2A. Where did you get 2A rating?


There is also some crosses at
http://www.ee.washington.edu/circuit...rts/cross.html

Also my page.
http://www.pitt.edu/~szekeres/shopchip.htm

In article ktYTf.7417$_Q.7383@edtnps89, "Dave" wrote:
"GregS" wrote in message
...
In article , "Travis
Jordan" wrote:
Dave wrote:
I've identified a bad transistor in the power supply of an audio
component, circa 1981. It's a 2SB527 PNP transistor... I had a bit
of a look around on the net and didn't find any quick easy sources.

Xref:
http://www.st.com/stonline/books/pdf/docs/4171.pdf



2SB527 PS TO125 110 v 90v 5v 2A 10WT 50minHFE
Froms Towers Transistor Selector No freq. given.

That's odd... I am finding all over the place on the net:

2SB527 TO220 110V 100V 0A8 10W 50minHFE 300maxHFE

That's 800mA rated, not 2A. Where did you get 2A rating?

Towers International Transistor Selector book.
2A max, 500ma hfe test.


There is also some crosses at
http://www.ee.washington.edu/circuit...rts/cross.html

Also my page.
http://www.pitt.edu/~szekeres/shopchip.htm


I read again with magnifiers, thats TO126 package. Perhaps the orginator
can identify which case?? TO220 or TO126 ??

"GregS" wrote in message
...
In article ,
(GregS) wrote:
In article , "Travis
Jordan"
wrote:

Most people would just use the NTEreplacement.
I found a distributor who claims to sell this Towers
International Transistor Selector from 1977 ??

greg

The more I read the responses, the more confused I get. There appears to be
literally hundreds of thousands of different transistors. They have various
ratings including, but not limited to:

ECO
EBO
BCO
Ic
Ib
hFE (min AND max)
Pd in Watts

Which ones need I concern myself with? The various "cross-reference" pages
all give different results when presented with search keywords. The most
confusing term I see is hFE... I consulted a catalog (digikey) to try to get
a handle on how these ratings correspond to each other, the various
packages, etc. The "hFE" rating may jump from 25 to 1000 between a "40V,
1A" and a "60V, 2A" transistor. ???

What I mean is, without getting into the meat of transistor theory and
operation (yeah, I know, I've got to go there sometime), is there a simple
way for me to pick an "equal or greater value" transistor to replace my bad
one? For example another poster suggested TIP42C as a replacement.

Here's how they stack up

Parameter 2SB527 TIP42C
V(CBO) 100 100
V(CEO) 110 100
Ic 0.8A 6A
Pd 10 10

I was all happy until I saw the hFE rating. This is a measure of
transistor's gain. There was no absolute maximum gain given for the TIP42C,
the value is "30" at 0.3A, so I'd imagine that might approach the value of
"55" given as the absolute max on the 2SB527 as Ic approaches zero on the
TIP42C.

Thanks a lot for your assistance so far, I think I'll rummage around a bit
and see if I can scare up ANY PNP power transformer rated at 100V and 1A.

"GregS" wrote in message
...
In article ktYTf.7417$_Q.7383@edtnps89, "Dave"
wrote:
I read again with magnifiers, thats TO126 package. Perhaps the orginator
can identify which case?? TO220 or TO126 ??

It's a TO-220 looking at it...

In article nbZTf.7431$_Q.1725@edtnps89, "Dave" wrote:
"GregS" wrote in message
...
In article ,
(GregS) wrote:
In article , "Travis
Jordan"
wrote:

Most people would just use the NTEreplacement.
I found a distributor who claims to sell this Towers
International Transistor Selector from 1977 ??

greg

The more I read the responses, the more confused I get. There appears to be
literally hundreds of thousands of different transistors. They have various
ratings including, but not limited to:

ECO
EBO
BCO
Ic
Ib
hFE (min AND max)
Pd in Watts

Which ones need I concern myself with? The various "cross-reference" pages
all give different results when presented with search keywords. The most
confusing term I see is hFE... I consulted a catalog (digikey) to try to get
a handle on how these ratings correspond to each other, the various
packages, etc. The "hFE" rating may jump from 25 to 1000 between a "40V,
1A" and a "60V, 2A" transistor. ???

What I mean is, without getting into the meat of transistor theory and
operation (yeah, I know, I've got to go there sometime), is there a simple
way for me to pick an "equal or greater value" transistor to replace my bad
one? For example another poster suggested TIP42C as a replacement.

Here's how they stack up

Parameter 2SB527 TIP42C
V(CBO) 100 100
V(CEO) 110 100
Ic 0.8A 6A
Pd 10 10

I was all happy until I saw the hFE rating. This is a measure of
transistor's gain. There was no absolute maximum gain given for the TIP42C,
the value is "30" at 0.3A, so I'd imagine that might approach the value of
"55" given as the absolute max on the 2SB527 as Ic approaches zero on the
TIP42C.

Thanks a lot for your assistance so far, I think I'll rummage around a bit
and see if I can scare up ANY PNP power transformer rated at 100V and 1A.

I'm still showing BD140 as a replacement for a 2SC527 TO126

Raising max current usually lowers HFE, so keep it near.
As long as the voltages are above, don't worry too much unless
your driving max current which stresses max voltage limits.
Keep HFE rating near. Changing parameters too much may
cause circuit opperation changes.Generally, higher voltage transistors
have less current gain. Darlington's have a magnitude greater
HFE's

greg

"GregS" wrote in message
...
In article nbZTf.7431$_Q.1725@edtnps89, "Dave"
wrote:
"GregS" wrote in message
...
In article ,
(GregS) wrote:
In article , "Travis
Jordan"
wrote:

Most people would just use the NTEreplacement.
I found a distributor who claims to sell this Towers
International Transistor Selector from 1977 ??

greg

The more I read the responses, the more confused I get. There appears to
be
literally hundreds of thousands of different transistors. They have
various
ratings including, but not limited to:

ECO
EBO
BCO
Ic
Ib
hFE (min AND max)
Pd in Watts

Which ones need I concern myself with? The various "cross-reference"
pages
all give different results when presented with search keywords. The most
confusing term I see is hFE... I consulted a catalog (digikey) to try to
get
a handle on how these ratings correspond to each other, the various
packages, etc. The "hFE" rating may jump from 25 to 1000 between a "40V,
1A" and a "60V, 2A" transistor. ???

What I mean is, without getting into the meat of transistor theory and
operation (yeah, I know, I've got to go there sometime), is there a
simple
way for me to pick an "equal or greater value" transistor to replace my
bad
one? For example another poster suggested TIP42C as a replacement.

Here's how they stack up

Parameter 2SB527 TIP42C
V(CBO) 100 100
V(CEO) 110 100
Ic 0.8A 6A
Pd 10 10

I was all happy until I saw the hFE rating. This is a measure of
transistor's gain. There was no absolute maximum gain given for the
TIP42C,
the value is "30" at 0.3A, so I'd imagine that might approach the value
of
"55" given as the absolute max on the 2SB527 as Ic approaches zero on the
TIP42C.

Thanks a lot for your assistance so far, I think I'll rummage around a
bit
and see if I can scare up ANY PNP power transformer rated at 100V and
1A.

I'm still showing BD140 as a replacement for a 2SC527 TO126


AHHHH, I am seeking replacement of 2S_B_527, not 2S_C_527 as you note,
above.

Raising max current usually lowers HFE, so keep it near.
As long as the voltages are above, don't worry too much unless
your driving max current which stresses max voltage limits.
Keep HFE rating near. Changing parameters too much may
cause circuit opperation changes.Generally, higher voltage transistors
have less current gain. Darlington's have a magnitude greater
HFE's


By "near", what do you mean. I looked at the hFE vs. DC amps for the TIP42C
and it appears to range from about 20 to 100, whereas the 2SB527 is spec'ed
at 55 to 300. Close enough? I can't find a curve for the 2SB527. The
NTE292 looks pretty good too with hfe of 15 to 150.

greg

Howdy Dave......I like your simple solution to use a 7915 from your junk
box and in the process, simplifying your circuitry a little! Of course
my first choice would have been something like a 7912 with a single gen
purpose diode (1N4001 etc) inserted in the leg to ground to bump the reg
voltage output up nearer to 13. With your 7915 you could likewise add a
couple of similar diodes in series with the output to lower the voltage
to your load.

Keep on tinkering.


Gord

"G" wrote in message
...
Howdy Dave......I like your simple solution to use a 7915 from your junk
box and in the process, simplifying your circuitry a little! Of course
my first choice would have been something like a 7912 with a single gen
purpose diode (1N4001 etc) inserted in the leg to ground to bump the reg
voltage output up nearer to 13. With your 7915 you could likewise add a
couple of similar diodes in series with the output to lower the voltage
to your load.

Keep on tinkering.

I'd like to go the diode route as they are more readily available than any
particular transistor. How would I wire them up as relates to my 7915 to
drop (actually raise) the voltage by 2V to -13VDC?

Each diode has a voltage drop and I just string 'em together to add up to
2VDC and tie them from the output of the 7915 to ground? I always figured a
diode was like a one-way resistor. Could I just use a resistor to ground to
get rid of some of my voltage? And, if so, how do I size it if I don't know
my current through the circuit? (I can't measure it, the transistor is
dead). Trial and error is a laborious process.

How can a diode RAISE the voltage of a 7912 (I'll dig around, might have one
somewhere)? Thanks a lot and pardon my ignorance.

Dave



Gord

Dave you wouldn't put the diodes from the 7915 output to ground but from
the output to your load in series......being a negative polarity output
you'd put the cathode towards the 7915 (and any additional diodes as well).

The trick to bumping up the voltage of a 3 terminal fixed regulator is
to insert a diode between the ground pin and ground (keep in mind to
insulate the tab if you do this!). The regulated voltage will now be
pushed up by the junction voltage of the diode or diodes (Diodes placed
as such in a 7912 would have their cathode face the ground pin.....anode
to ground).

clear as mud?

You mentioned not knowing the load current Dave.....(with the limits
that you could look up the max collector current and device dissipation
for the old device and deduce a ballpark figure). The beauty of using
the diodes is that they behave (when forward biased...within their
normal operating range) as a somewhat-constant voltage drop despite
current.....thus no big math for some quick trials.

Gord

On Tue, 21 Mar 2006 16:13:47 GMT, "Dave"
wrote:

I've identified a bad transistor in the power supply of an audio component,
circa 1981. It's a 2SB527 PNP transistor... I had a bit of a look around on
the net and didn't find any quick easy sources. This transistor's sole
function is to convert -26VDC coming off one side of a bridge rectifier
to -13 volts. It's wired up as follows, and I apologize for not being more
skilled in ascii art or I'd try to draw it.

The collector is the -26VDC input. It is connected to ground via a 100uF
cap.
The emitter is the -13VDC output. It is connected to ground via a 10uF cap.
The base is connected to a series 470-ohm resistor, then a parallel 10uF cap
(to ground), then a parallel zener diode (to ground), then a 5.6K-ohm
resistor, then to the collector.

My question is thus: if my downstream components can get by with -15VDC,
can I just substitute a 7915 15VDC negative voltage regulator? There are no
feedback connections from any other part of my circuit to this transistor,
it's output voltage should not vary under normal conditions. And, by freak
coincidence, the pinout of the regulator matches my circuit perfectly, it'd
be a straight swap and removing a couple of resistors. And perhaps most
importantly, I have one.



We used to sub a 2sb633 which cost about a U.S. dollar. Chuck

In article sgZTf.7433$_Q.4467@edtnps89, "Dave" wrote:

"GregS" wrote in message
...
In article ktYTf.7417$_Q.7383@edtnps89, "Dave"
wrote:
I read again with magnifiers, thats TO126 package. Perhaps the orginator
can identify which case?? TO220 or TO126 ??

It's a TO-220 looking at it...

If its a TO220 then its a TO220.
I found my Japanese cross reference book. Here goes. Still a TO126

2SB527 SAN 2SB631 TOS 2SA815 NEC 2SA985 MAT 2SA1110 ROHM 2SB1085

A trouble may reside in you transistor manufacturer. You would have to look
at the manufacturers spec sheet to get exact figures.

If you make a regulator with diodes, put some capacitance across
the diodes.

greg

"G" wrote in message
...
Dave you wouldn't put the diodes from the 7915 output to ground but from
the output to your load in series......being a negative polarity output
you'd put the cathode towards the 7915 (and any additional diodes as
well).

The trick to bumping up the voltage of a 3 terminal fixed regulator is
to insert a diode between the ground pin and ground (keep in mind to
insulate the tab if you do this!). The regulated voltage will now be
pushed up by the junction voltage of the diode or diodes (Diodes placed
as such in a 7912 would have their cathode face the ground pin.....anode
to ground).


Makes sense. One question: why do you say insulate the tab? If the tab is
already connected to ground, and you are just adding a diode, wouldn't you
only have the 1V of potential difference between ground and the pin with a
diode? Would I want to use a mica insulator between the tab and heatsink?

clear as mud?

"Dave" wrote in message
news:d3fUf.1230$K11.421@clgrps12...


Makes sense. One question: why do you say insulate the tab? If the tab
is
already connected to ground, and you are just adding a diode, wouldn't you
only have the 1V of potential difference between ground and the pin with a
diode?

Because the tab is connected to the ground pin internally. If you ground the
tab then the pin is also grounded, bypassing the diode.

Would I want to use a mica insulator between the tab and heatsink?


Yes. You'd need the whole heatsink 'kit', including the plastic insulating
collar which goes on the bolt, or a plastic bolt.

Dave

We have original 2SB527 in stock for US$1.99 each.

http://www.acme-sales.net

Regards,

Glen Goodwin
ACME Enterprises of Orlando
1-800-575-9833

Dave wrote:
I've identified a bad transistor in the power supply of an audio component,
circa 1981. It's a 2SB527 PNP transistor... I had a bit of a look around on
the net and didn't find any quick easy sources. This transistor's sole
function is to convert -26VDC coming off one side of a bridge rectifier
to -13 volts. It's wired up as follows, and I apologize for not being more
skilled in ascii art or I'd try to draw it.

The collector is the -26VDC input. It is connected to ground via a 100uF
cap.
The emitter is the -13VDC output. It is connected to ground via a 10uF cap.
The base is connected to a series 470-ohm resistor, then a parallel 10uF cap
(to ground), then a parallel zener diode (to ground), then a 5.6K-ohm
resistor, then to the collector.

My question is thus: if my downstream components can get by with -15VDC,
can I just substitute a 7915 15VDC negative voltage regulator? There are no
feedback connections from any other part of my circuit to this transistor,
it's output voltage should not vary under normal conditions. And, by freak
coincidence, the pinout of the regulator matches my circuit perfectly, it'd
be a straight swap and removing a couple of resistors. And perhaps most
importantly, I have one.

In article d3fUf.1230$K11.421@clgrps12, "Dave"
wrote:

"G" wrote in message
...
Dave you wouldn't put the diodes from the 7915 output to ground but from
the output to your load in series......being a negative polarity output
you'd put the cathode towards the 7915 (and any additional diodes as
well).

The trick to bumping up the voltage of a 3 terminal fixed regulator is
to insert a diode between the ground pin and ground (keep in mind to
insulate the tab if you do this!). The regulated voltage will now be
pushed up by the junction voltage of the diode or diodes (Diodes placed
as such in a 7912 would have their cathode face the ground pin.....anode
to ground).


Makes sense. One question: why do you say insulate the tab? If the tab is
already connected to ground, and you are just adding a diode, wouldn't you
only have the 1V of potential difference between ground and the pin with a
diode? Would I want to use a mica insulator between the tab and heatsink?

Dave-

I agree with G for the most part. I prefer the 7912 approach rather then
using the 7915. As someone else suggested, a capacitor from the output to
ground would be a good idea. I think you mentioned having one in the
original circuit.

Another alternative to the 7912 approach would be to use the negative
version of an LM317 with pair of resistors instead of the one diode. One
resistor would be connected from the regulator's output to its common
("adj") terminal. The other would be connected from the common terminal
to ground. Values would be chosen to produce the required output
voltage. The LM317 regulator actually has about 1.2 volts output plus the
voltage dropped by the resistor to ground. I assume there is a negative
version of the LM317, if you wanted to look further.

Of course an exact replacement transistor is the most sure-fire solution.
If you were to use an alternative part, I suggest using one rated for at
least the minimum hfe of the original part, or at least one having an
actual (measured) hfe of that value or higher.

Fred

"Glen in Orlando" wrote in message
...
We have original 2SB527 in stock for US$1.99 each.

http://www.acme-sales.net

Holy sh#t, this site is a GOLDMINE! You sell transistors that haven't been
made since 1975! Tons of them!

Thanks, it's in my bookmark file. I already bought a TIP42C (over-rated,
but at $1.99 the price was right) at my local electronics store. BTW, how
much is shipping to Canada?

Looks like you're getting lots of help Dave.
The comment about insulating the tab is so that you DON'T negate the
effect of adding the diode. The tab is common with the ground pin so
you'd be bypassing what you'd be trying to accomplish

Gord

On Wed, 22 Mar 2006 00:42:29 GMT, G wrote:

(snip)

The trick to bumping up the voltage of a 3 terminal fixed regulator is
to insert a diode between the ground pin and ground (keep in mind to
insulate the tab if you do this!).

Sorry to be a spolier, but according to my data sheets the tab is connected to
pin 2 (whic is INPUT on a 7912 and presumably on other 79XX regulators). So the
O/P is going to have to go the insulated mounting route regardless of the diode.

Howdy Budgie....right you are.....thats not being a spoiler but
just being helpful . Must admit I based my experience has been with
the positive VR's (obvious eh!). Having said that......the tab of a
79xx wouldn't necessarily need to be insulated but it has to be kept in
mind for sure. (anyone here ever tried building their regulator into a
grounded side of a rectifier heheh......it works just fine - just looks
disconcerting when you look at the diagram).

"Dave" wrote in message
news:%CVTf.6013$J43.2877@edtnps90...
I've identified a bad transistor in the power supply of an audio
component,
circa 1981.

Well I went with a TIP42C, over-rated (6A vs. the 0.8A I am replacing AND
that's probably over-engineered) but available locally. I don't have any
mica insulators or plastic screws and they are an hour drive (or $15
shipping) away.

Thanks for everyone's help, I learned a great deal. BTW, I threw the new
PNP into my DMM's transistor testor and it came up with an hFE of 390. I am
thinking that this is a fairly useless number other than to show that the
transistor is functional as the hFE measurement will vary greatly with input
current. Wonder what the old one would weigh in at? Interestingly checking
the old transistor with a multimeter showed perfectly normal behavior, B-E
conducted one way only, B-C conducted one way only, C-E did not conduct.
But it didn't work in my transistor tester, came up 000 for hFE.

Again, thanks for the assistance.

Dave

In article d%AUf.955$B_1.194@edtnps89, "Dave" wrote:

"Dave" wrote in message
news:%CVTf.6013$J43.2877@edtnps90...
I've identified a bad transistor in the power supply of an audio
component,
circa 1981.

Well I went with a TIP42C, over-rated (6A vs. the 0.8A I am replacing AND
that's probably over-engineered) but available locally. I don't have any
mica insulators or plastic screws and they are an hour drive (or $15
shipping) away.

I still don't know where you got that spec. What was the manufacturer of that
obsolete unit.

Thanks for everyone's help, I learned a great deal. BTW, I threw the new
PNP into my DMM's transistor testor and it came up with an hFE of 390. I am
thinking that this is a fairly useless number other than to show that the
transistor is functional as the hFE measurement will vary greatly with input
current. Wonder what the old one would weigh in at? Interestingly checking
the old transistor with a multimeter showed perfectly normal behavior, B-E
conducted one way only, B-C conducted one way only, C-E did not conduct.
But it didn't work in my transistor tester, came up 000 for hFE.

Again, thanks for the assistance.

You really need sets of curves to get a real indication of things.
I have mostly tested them out with an analog ohmeter, my favorite.
Sometimes you will see extra leakage on CE or other terminals
when they are bad. I have not tested a bad unit with the diode
test function, which should indicate some voltage drop across CE.
greg

Dave wrote:
"Glen in Orlando" wrote in message
...

We have original 2SB527 in stock for US$1.99 each.

http://www.acme-sales.net


Holy sh#t, this site is a GOLDMINE! You sell transistors that haven't been
made since 1975! Tons of them!

Thanks, it's in my bookmark file. I already bought a TIP42C (over-rated,
but at $1.99 the price was right) at my local electronics store. BTW, how
much is shipping to Canada?

Glad you like it, Dave! We carry a lot of "new old stock"
items, as well as the "latest and greatest."

Shipping to Canada is the same as anywhere else, and
shows up in the shopping cart as you add items. (BTW we ship
to Canada every day).

Orders over US$50.00 - FREE shipping and handling
Orders US$20.01 to US$50.00 - S & H = US$6.99
Orders US$10.00 to US$20.00 - S & H = US$8.49
Orders unders US$10.00 - S & H = US$11.99

For orders under US$50.00 a small additional charge
will be added for flybacks.

Typically we use US Postal Service Global Priority Mail
to Canada, which arrives in about 4-7 days.

If you need more information please call us toll-free at
1-800-575-9833 (USA and Canada) or 1-407-296-2333.

Glen Goodwin
ACME Enterprises of Orlando
http://www.acme-sales.net

"GregS" wrote in message
...
In article d%AUf.955$B_1.194@edtnps89, "Dave"
wrote:

"Dave" wrote in message
news:%CVTf.6013$J43.2877@edtnps90...
I've identified a bad transistor in the power supply of an audio
component,
circa 1981.

Well I went with a TIP42C, over-rated (6A vs. the 0.8A I am replacing AND
that's probably over-engineered) but available locally. I don't have any
mica insulators or plastic screws and they are an hour drive (or $15
shipping) away.

I still don't know where you got that spec. What was the manufacturer of
that
obsolete unit.

http://www.geocities.com/saphanlex/p/tr.htm
http://www.datasheets.org.uk/specsheet.php?part=2SB527
http://www.datasheets.org.uk/databoo...book.php?q=100
translated directly from Japanese:
http://translate.google.com/translat...en-US:official

I'll have a look at the part and get the manufacturer.

Thanks for everyone's help, I learned a great deal. BTW, I threw the new
PNP into my DMM's transistor testor and it came up with an hFE of 390. I
am
thinking that this is a fairly useless number other than to show that the
transistor is functional as the hFE measurement will vary greatly with
input
current. Wonder what the old one would weigh in at? Interestingly
checking
the old transistor with a multimeter showed perfectly normal behavior,
B-E
conducted one way only, B-C conducted one way only, C-E did not conduct.
But it didn't work in my transistor tester, came up 000 for hFE.

Again, thanks for the assistance.

You really need sets of curves to get a real indication of things.
I have mostly tested them out with an analog ohmeter, my favorite.
Sometimes you will see extra leakage on CE or other terminals
when they are bad. I have not tested a bad unit with the diode
test function, which should indicate some voltage drop across CE.
greg

In article 0kDUf.1295$B_1.651@edtnps89, "Dave" wrote:

"GregS" wrote in message
...
In article d%AUf.955$B_1.194@edtnps89, "Dave"
wrote:

"Dave" wrote in message
news:%CVTf.6013$J43.2877@edtnps90...
I've identified a bad transistor in the power supply of an audio
component,
circa 1981.

Well I went with a TIP42C, over-rated (6A vs. the 0.8A I am replacing AND
that's probably over-engineered) but available locally. I don't have any
mica insulators or plastic screws and they are an hour drive (or $15
shipping) away.

I still don't know where you got that spec. What was the manufacturer of
that
obsolete unit.

http://www.geocities.com/saphanlex/p/tr.htm
http://www.datasheets.org.uk/specsheet.php?part=2SB527
http://www.datasheets.org.uk/databoo...book.php?q=100
translated directly from Japanese:
http://translate.google.com/translat...ge3.nifty.com/
ebina2540/data/2SB/2SB0501-0600.htm&prev=/search%3Fq%3D2sb527%2Brating%26hl%3De
n%26hs%3DQfp%26lr%3D%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-USfficial

I'll have a look at the part and get the manufacturer.

Taken from my Towers 1980 edition databook, the main
difference is the packge type, clearly a TO126 as
the replacement shows2sb631
http://www.ortodoxism.ro/datasheets/..._e/2SB631K.pdf
The max current spec does vary among the bunch.

I have about 8 different replacement numbers as I have gone through all this.

greg

Thanks for everyone's help, I learned a great deal. BTW, I threw the new
PNP into my DMM's transistor testor and it came up with an hFE of 390. I
am
thinking that this is a fairly useless number other than to show that the
transistor is functional as the hFE measurement will vary greatly with
input
current. Wonder what the old one would weigh in at? Interestingly
checking
the old transistor with a multimeter showed perfectly normal behavior,
B-E
conducted one way only, B-C conducted one way only, C-E did not conduct.
But it didn't work in my transistor tester, came up 000 for hFE.

Again, thanks for the assistance.

You really need sets of curves to get a real indication of things.
I have mostly tested them out with an analog ohmeter, my favorite.
Sometimes you will see extra leakage on CE or other terminals
when they are bad. I have not tested a bad unit with the diode
test function, which should indicate some voltage drop across CE.
greg