Transistors

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Hi Folks

Having some trouble finding some transistors.  

I am repairing a switch mode power supply and have a number of transistors that need replacing. The issue is I can't seem to find them online....maybe my google fu is out of whack or I have forgotten something obvious.

Any way there are 3 different types of transistors

first is marked as follows

2001
-2J

Second

2005
-2I

third
P4M
 25

if anyone can help me out or point me in the right direction that would be greatly appreciated.

Regards

Richard  

Re: Transistors
Richard,

     It would be helpful to know the make and model of the power supply (or  
the device it is part of), and the physical package of the transistors.  
If you know the schematic reference (ie Q25) that would be good too.

Regards,
Tim


On 7/13/2019 6:53 AM, snipped-for-privacy@fastmail.fm wrote:
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Re: Transistors
Hi Tim

So it is a power supply out of a Sun Microsystems SPARC Classic computer.

the PowerSupply is marked as follows on the outside
Sun P/N 300-1101-01 Rev A
Model: PEX643-30
Made by FDK Fuji Electrochemcical Co Ltd

The circuit board is marked with the following
PCB1750 A06-119271D

Not easy or not marked as to the parts

the transistors in questions are TO-92 and are all on the low voltage side of the switcher.

hope that provides more detail.

Cheers

Richard
  
On Saturday, July 13, 2019 at 9:26:55 PM UTC+10, Tim Schwartz wrote:
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Re: Transistors
On Saturday, July 13, 2019 at 4:48:23 AM UTC-7, snipped-for-privacy@fastmail.fm wrote:
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Good info; the date might be 2000 or earlier, so
there's a good chance old-line part-number xrefs will help
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Lots of Japanese transistors have different pinout from US types; for TO-92,
US normal is (facing flat, with wires DOWN, left to right) E-B-C
Japan normal is E-C-B
You can usually distinguish the two by a multimeter's diode-check function (assuming a working
transistor) without desoldering.

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If it helps, NTE crossreferences for (P4M) include NTE159, a general-purpose PNP
(see <https://www.nteinc.com and use the crossreference search)

It is usual for one TO-92 item on the low voltage side to be a TL431 voltage reference...

Re: Transistors
Richard,

     It would be helpful to know the make and model of the power supply (or  
the device it is part of), and the physical package of the transistors.  
If you know the schematic reference (ie Q25) that would be good too.

Regards,
Tim


On 7/13/2019 6:53 AM, snipped-for-privacy@fastmail.fm wrote:
Quoted text here. Click to load it


Re: Transistors
Am 13.07.19 um 12:53 schrieb snipped-for-privacy@fastmail.fm:
Quoted text here. Click to load it

Try to get the schematic, and then you should be able to figure out,
what for a kind of transistor you are looking for. Second bet is, you
have to add strings like "2SB" oder "2SA" for "2SA2005" or something
similar. Search for the appropriate datasheets, good luck.

Holger

Re: Transistors
Take some detailed pictures of the board top and bottom. If I can figure ou
t how it is designed I can figure out a replacement fairly fast.  

Either upload them somewhere or just send them to me. Hosting is nice, I us
ed to have hosting until Dropbox stuck it up my ass and I don't want them a
t all anyway because they won't do what I want done. This year I am just go
ing to dig in the old pocket and pay for some decent hosting. Are you in an
y forums that accept pictures in posts ? If so I can tell you how to hotlin
k.  

Now I need high definition well lit pictures, this is reverse engineering.  
It's not much fun anymore actually.

Re: Transistors
I have found this site quite useful on several occasions finding equivalents for vintage transistors:

https://alltransistors.com/crsearch.php?mat=Si&struct=NPN&pc20%0&ucb12%0&uce12%0&ueb=7&ic20%&tj20%0&ft=1&cc50%0&hfe20%&caps=TO3

Mostly, "better" devices are available these days as drop-in replacements for whatever it was from those days.  


Peter Wieck  
Melrose Park, PA  

Re: Transistors
On Saturday, 13 July 2019 11:53:53 UTC+1, snipped-for-privacy@fastmail.fm  wrote:
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If you can't find equivalents, work out what specs are needed from the circuit diag & get something that'll do that. People often get too hung up on equivalents imho.


NT

Re: Transistors
On Saturday, July 13, 2019 at 12:53:53 PM UTC+2, snipped-for-privacy@fastmail.fm wrote:
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Hi,  
you might want to post a question on vcfed's forum:

http://www.vcfed.org/forum/forumdisplay.php?26-Unix-Xenix-Linux-Workstations

Someone there could have a (even partial) schematic of that PSU and help you getting the right replacements.
The closest SUN workstation that I have at home is a SS10 so I don't think there're chances that it uses the same PSU as the Classic.
By the way, what's wrong with the original parts?


Re: Transistors
On 2019/07/16 7:24 a.m., snipped-for-privacy@gmail.com wrote:
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...

The top was blown off of one of them...might have let the magic smoke out!

John :-#)#

--  
(Please post followups or tech inquiries to the USENET newsgroup)
                      John's Jukes Ltd.
We've slightly trimmed the long signature. Click to see the full one.
Re: Transistors
On Saturday, July 13, 2019 at 8:53:53 PM UTC+10, Richard Edwards wrote:
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Thanks to everyone for the responses and offers. I think I have enough to go on. Will update once/if i resolve...

Re: Transistors
On Friday, July 19, 2019 at 10:55:12 AM UTC+10, Richard Edwards wrote:
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So just to round this out the replacements were
2n2001
2n2005
P4M
Also had to replace a B688

PSU now working.

Thanks to all who offered assistance and ideas.  

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