HP9100 EHT oscillator transistor

From: Eric Smith <eric_at_brouhaha.com>
Date: Tue Dec 22 00:03:18 1998

Tony Duell wrote:
> I've got an HP9100 to repair, and the first fault is that the transistor
> on the EHT power supply board is short-circut all ways round.
>
> Alas the only number I have for it is the HP custom number, 1854-0322.

A friend who works for HP looked it up in their database, and emailed me
the following information:

    1854-0322, Silicon Power NPN TO-8 can transistor,
               IC = 2.5 A max
               PD = 25W max at TC

               Electrical:
                 BVCEQ = 40 V min
                 HFE = 20 min to 100 max at IC=300 MA
                 VCE(SAT) = 12.5 V max at IC = 2.5 A

    Suppliers were listed as RCS, Harris and GECO (General Electric I think).

    Maybe this will be enough data to figure out a good replacement.

    Hope this helps! BTW, at 25 W max power dissipation, I'd make sure there
    was a heat sink on the TO-8 can!

These specs do sound pretty similar to a 2N1701. The TO-8 case is apparently
similar to the TO-5 case but larger. 'RCS' was probably supposed to be RCA,
since RCA did make the 2N1701.

It's unfortunate that he was not able to get the vendor part numbers, but
I doubt that the original parts are still made.

Motorola claims that the replacment for a 2N1701 is a 2N4910, which is in
a TO-66 case (like a TO-3, only smaller). Unfortunately this is not a good
mechanical replacement for the TO-8.

Searching for 2N1701 with Altavista revealed several companies that may
stock them.

Rich suggests that you might also consider the MJE340. But the pinout
is in the wrong order as compared to the 2N1701.

Cheers,
Eric
Received on Tue Dec 22 1998 - 00:03:18 GMT