2. amps-preamps
  3. 1100106840

Repairing a B&K ST140

Trying to find answers to some transistor questions. I have the schematics from B&K but they contain some odd part numbers. Q2,3,5,6,7, all are "PN4889" digikey has no idea what they are. Any one out there have a clue? Are there any mods I might make to this thing before I seal it back up?

System: Rotel CD player; Adcom Pre Amp, Which I modified "Straight wire"; Adcom GFA555 for the low end; B&KST140 for the high/mid end; B&W 801 Series 2, BiWired; NAD tuner; Monster cable sprinkled around...

Any way thanks in advance for the help.

Don
soldernazi
mwilson
430 posts
 
Here's one possible match, for example:

http://www.chipdocs.com/pndecoder/datasheets/FAIR/PN4889.html?ReR=GG

Partname: PN4889
Description: PNP low noise high voltage amplifier.
Manufacturer: Fairchild Semiconductor
Package: TO-92
Pins: 3
Oper. temp.: 0 to 150
soldernazi OP
2 posts
 
Yea, I did a duh. Sorry about that. I found what i was looking for soon after posting this note.

New related question, what would you recomend as to a manufacture for these transisters? And the out put mosfets?

Any mods?

Don
mwilson
430 posts
 
The link I copied above said Fairchild Semi for the PN4889 - I don't know if it's their chip or if the PN4889 is a generic designation. I don't have an ST140 anymore to pop open for a better look/guess. As for the Mosfets, MOST (but not all) ST140s had Hitachi output devices -- check out this archived thread for some more info:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1074209541&read&keyw&zzbAAk

If yours is black faceplate + champagne/gold rack handles, I gather it's probably got Hitachis. If it has the red/blue "sonata series" lettering on the front, it may have something else. Audiogon member "Sean" is the most likely person to know the answer to this.
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