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HP 400EL ac voltmeter
#1

 I'm trying to troubleshoot this tester due to erratic readings. I found the (Q7) voltage reading not right.
This transistor has a heat sink that pushes down on top of it. So it runs at least fairly warm. It is in a TO-18 package.
  It is staying cold to touch, any how the voltages called for on schematic are on the left. Mine on right.

Emitter   _-6.7v                                      Emitter -6.7v

Base    -7.4v                  My readings are: Base -7.4 v

Collector    -21.5v                                   Collector  -12v

above  readings were taken to ground with fluke DVM

 The collector voltage seems way low.

 The transistor has the # 3-009 on it. I'm trying to figure out what transistor equivalent to purchase.
It shows it being a PNP on the schematic, but the Mouser site has a 2n3009 as NPN.
http://www.mouser.com/ds/2/68/lssgp056-12668.pdf

 I'm confused Icon_crazy  Here is what mouser shows available.

http://www.mouser.com/Semiconductors/Dis...kaZ1z0y4cn

 Can someone advise me on which transistor I could use as a replacement? Thanks
 Here is the manual with schematic on page 45 and voltage chart on page 32.  all transistors on the tested within +/- 5% except the collector of Q7

file:///C:/Users/Mike/Downloads/400e_service%20(2).pdf
Sorry I see the download of schematic did not work will try to get it up


 
 








 


Messages In This Thread
HP 400EL ac voltmeter - by KCMike - 08-10-2016, 04:07 PM
RE: HP 400EL ac voltmeter - by Radioroslyn - 08-10-2016, 07:33 PM
RE: HP 400EL ac voltmeter - by KCMike - 08-11-2016, 09:04 AM



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