Looking for Keithley 177 DMM Schematic.

• Looking for Keithley 177 DMM Schematic.
  Posted by Jay_Diddy_B on 10 Feb, 2014 22:57
• Hi group,
  
  I am looking for a nice, readable, schematic for the Keithley 177 DMM.
  
  I have found the one on the Keithley website that is complete, but barely readable.
  
  I found another one which was very readable, but only half the schematic.
  
  I have one of these for repair.
  
  Many thanks !!
  
  Jay_Diddy_B
  
  
• #1 Reply
  Posted by wiss on 10 Feb, 2014 23:06
• Register at keithley.com and download it from there?
• #2 Reply
  Posted by Jay_Diddy_B on 11 Feb, 2014 00:11
• Wiss,
  
  Thank you for the reply. I have registered with Keithley and downloaded the manual. This is where I got the one with unreadable schematics. The file size is 2740kB (according to Windows).
  
  Here is a sample of the schematic:
  
  
  
  Thanks,
  
  Jay_Diddy_B
  

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• #3 Reply
  Posted by wiss on 11 Feb, 2014 01:02
• Sorry, a bit quick to reply...
  You only need the scematics? I can see if there are any at work...
• #4 Reply
  Posted by wiss on 11 Feb, 2014 08:58
• I did find a 177 so there is a reasonably high probability that the manual is somewhere in the building, the person responsible for it is not here until Thursday, I`ll ask then.
• #5 Reply
  Posted by wiss on 13 Feb, 2014 09:07
• No luck
  It might be somewhere but it will take a large amount of time to locate it...
• #6 Reply
  Posted by Jay_Diddy_B on 13 Feb, 2014 13:11
• Wiss,
  
  Thank you very much for your efforts.
  
  I will try and fix the meter with the schematic in the manual that I have.
  
  Jay_Diddy_B
  
• #7 Reply
  Posted by MBY on 17 Feb, 2014 14:32
• I had exactly the same problem trying to fix my Keithley 177 and building a RS232 interface for it. I ended up with trying to recreate the schematics and after many hours I got what I suspect is a accurate redraw.
  
  Hope it helps! I cannot guarantee that every connection I've drawn is correct, but I succeeded both in fixing my DMM and to create a RS232-interface using a AVR.
  
  I hope its not the power supply that is the problem in your case. I redraw almost all BUT the power supply, since it worked ok for me.
  
  
  
  

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• #8 Reply
  Posted by Jay_Diddy_B on 17 Feb, 2014 16:01
• MBY,
  
  Thank you for providing the re-touched schematic. I found a manual here:
  
  http://exodus.poly.edu/~kurt/manuals/manuals/Keithley/KEI%20177%20Instruction.pdf
  
  This manual is little cleaner than the manual from the Keithley website. Unfortunately it contains only half of the schematic. It does include the power supply section. I have attached the pdf with the power supply section.
  
  I have three of these meters that I got in a package deal with a 175, 197 and three 177. None of the working.
  
  All of them, except one of the 177 are repaired.
  
  The two 177 had dirty switches, I cleaned the switches and then cleaned the board. The remaining 177 has a bad ICL71C03, the main chip.
  
  Thank you again!!
  
  Regards,
  
  Jay_Diddy_B
  
  

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  K177 half schematic.pdf
• #9 Reply
  Posted by lowimpedance on 18 Feb, 2014 02:52
• Just to note that the RACAL DANA 4003 DMM is a rebadged Keithley 177.
  On ebay there is a seller 'teoulet' (Tucker electronics) selling manuals and they have currently a listing for the 4003 manual, which in the photo is the main schematic and P/S schematic.
  They are actually quite readable so you can "re touch" your crummy copy if any part of it is not readable!!.
  Look for 'DANA manual 4003 '!. and see what I mean.
  
  I have a 4003 but alas I do not have the handbook, and also have to get by with the awful copy as well.
  
  EDIT Aug 2018
  I did find a 177 manual and have uploaded a decent copy of the schematic and part layout in this thread ;
  
  https://www.eevblog.com/forum/repair/keithley-177-power-supply/
  
• #10 Reply
  Posted by Jay_Diddy_B on 18 Feb, 2014 03:20
• Hi,
  Here is the schematic picture from the teoutlet listing.
  
  
  Regards,
  
  Jay_Diddy_B
  

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