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

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

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 > Richard,

Good info; the date might be 2000 or earlier, so there's a good chance old-line part-number xrefs will help

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.

If it helps, NTE crossreferences for (P4M) include NTE159, a general-purpose PNP (see and use the crossreference search)

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

Am 13.07.19 um 12:53 schrieb snipped-for-privacy@fastmail.fm:

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

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.

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

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

Peter Wieck Melrose Park, PA

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

Hi, you might want to post a question on vcfed's forum:

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?

...

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

John :-#)#

Thanks to everyone for the responses and offers. I think I have enough to go on. Will update once/if i resolve...

So just to round this out the replacements were

PSU now working.

Thanks to all who offered assistance and ideas.