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HP 400EL ac voltmeter - Printable Version

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HP 400EL ac voltmeter - KCMike - 08-10-2016

 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/Discrete-Semiconductors/Transistors/Bipolar-Transistors-BJT/_/N-ax1sh?P=1z0yrkaZ1z0y4cn

 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


 
 








 

RE: HP 400EL ac voltmeter - Radioroslyn - 08-10-2016

Whooppppssss. Was looking at the wrong diagram! Your xsistor is HP p/n 1853-009. Couldn't find a crossover but are available here:     http://www.sphere.bc.ca/test/hp-parts/hpparts4.html  
For $7.
http://www.gellerlabs.com/HP%20400E%20EL.pdf

GL

RE: HP 400EL ac voltmeter - KCMike - 08-11-2016

Thanks Terry. I won't be on here for awhile. While looking for a schematic to download I clicked on a download that turned out to be some kind of virus/trojin hourse it took over the computer and know I'm trying to get rid of it.

By the way its called safefinder and I never seen one you could not uninstall till this one.