[time-nuts] Tektronix TM500 Series Help

Don @ True-Cal True-Cal at swbell.net
Sun Jan 3 00:07:11 UTC 2010


No, MJE3055T is a TO-220 (BCE) but the MJE3055 (or in my case JE3055) is a TO-127 (ECB) pinout.
  ----- Original Message ----- 
  From: David C. Partridge 
  To: 'Discussion of precise time and frequency measurement' 
  Sent: Saturday, January 02, 2010 4:22 PM
  Subject: Re: [time-nuts] Tektronix TM500 Series Help


  Isn't the pinout of the MJE3055 (BCE) different from the SJE924 (ECB).

  Dave 

  -----Original Message-----
  From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
  Behalf Of Don @ True-Cal
  Sent: 02 January 2010 20:33
  To: time-nuts at febo.com
  Subject: [time-nuts] Tektronix TM500 Series Help

  Happy New Year to all!

  In working on my TM501 which serves as the power supply for my AM503B
  current probe, I had to dismount the 2 series pass transistors from the TM
  case (heat sink). After repair (filter caps) and during remounting the
  circuit board, Q12 transistor TO-127 case fractured while bending the leads.
  This transistor is one of the two series pass transistors that some
  TM-Series modules use as external mounted power devices. These two
  transistors are used mostly with PSxxx power supply modules. They are not
  actually used as active components of the TM501 and fortunately for me, not
  used with the AM503B module so I am up and running again. I would like to
  fix this situation so I could use this TM501 with any/all modules.

  The manual (and device) says Q12 is an NPN, SI, Selected, TO-127 SJE924. For
  completeness, the complementary Q10 is a PNP, SI, TO-127 SJE925. These
  transistors types are the same across any TM-Series mainframe.

  I can't find any SJE or MJE 9xx reference. Does anyone have a cross
  reference or know of a substitute device for these transistors? I tried a
  MJE3055 which is very general purpose and it does not work with a PS503A
  power supply module. This, plus the word "Selected" in the manual, says to
  me that something (Hfe?) must be fairly critical. Another alternative is
  someone with a junker TM mainframe that would be willing to pull one or both
  of these transistors.

  Regards...
  Don
  _______________________________________________
  time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
  https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
  and follow the instructions there.


  _______________________________________________
  time-nuts mailing list -- time-nuts at febo.com
  To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
  and follow the instructions there.


More information about the time-nuts mailing list