Hi Bluestar,
I just got a 257 up and working. I don't remember the difference between the 157 and the 257. Supposedly the 257 will test CRTs, although on mine all the wires and the connector were cut off (as I would have done!
).
Go to
www.mzentertainment.com.
Dr Zee rebuilt a 257 and has not only the schematic but also simplified schematics for the SHORT and QUALITY test. If your 157 uses the same schematic, then the manual should be essentially the same. I think I got the 257 manual at
bama.sbc.edu. If not there, PM me and I can email you the PDF.
BTW, mine required: new LOAD pot, new test switch (MOM), new calibration resistor, and DEOXIT on the other switches, esp the rotaries. I calibrated mine on my line voltage which is a steady 118.5VAC. For calibration tips go to
http://tubesound.com/2009/03/12/mercury-tube-testers/#more-457 which is a good pretty generic description of refurbishing the typical emission tester like the Accurates, Mercurys, etc.
Also go to
http://www.pmillett.com/Books/intro_Tom ... _Tubes.pdf and read chapter 8 on tube testers. Emission testers like the Accurate is a type 1 and not the best thing for your tubes
. I only use mine for testing for SHORTs, for testing rectifier tubes, and used radio tubes. I'm building a Type IV tester to test/match my audio tubes (see other thread) because its alot more affordable than a Hickok.
Good luck