THESE INSTRUCTIONS ARE FOR THE 400. For OTHER MODELS SEE the note dated 10-17-14 for clarification and further instructions.
1st OPTION...
1.) Measure and record the value of R110(R109).
2.) Disconnect one end of R116(R115). Measure R116(R115) and record. Do not reconnect yet.
3.) Determine what value resistance when in parallel with measured value of R116(R115) equals the measured value of R110(R109).
4.) Place ohm meter from pin #3 of phase inverter to ground.
5.) Adjust phase inverter for value determined in step #2.
6.) Reconnect R116(R115).
NEW AND IMPROVED way, and the way I did it. This involves no desoldering, soldering, or math. Just a DMM and a Jumper wire with 2 alligator clips. AGAIN! TURNED OFF AND UNPLUGGED!!!!
NOTE: PART #'s change due to SERIAL #'s.
For those having units with serials of 29999 and below, the relevent part #'s the B+ to Ground is C75C.
For those having units with Serials 48001 and above, the relevent part # of the B+ to Ground is C52C.
It's the SAME PART Just uses different part # on the schematics.
1.) Using an alligator clip lead, short the B+ supply point to the phase inverter tubes to ground. This would be the 320V source that appears across C52C. This is the 4 section CAN CAP.
2.) Ground the common lead of your ohm meter.
3.) Measure and record the resistance value that appears at pin #1 of the left and right phase inverter tubes.
4.) Connect your ohm meter to pin #3 of the left and right phase inverter tubes, and adjust their respective phase inverter control for the respective value noted in Step #3 above.
5.) Remove the alligator clip lead.
Close it up and enjoy.
It took me 5 minutes total to adjust the PI on both sides with original pots. Actually it took me longer to clean them with DeOxit than it did to adjust them. They can be touchy but making a mark on the dial and face 1st, then spray conservatively with DeOxit, and exercise 40-50 times. Blow it dry (cool setting on lungs) and do your adjustments.
A very Big thanks to Dave Gillespie. I hereby nominate him for FISHER Forum M.O.T.Y. Any seconds???
Larry
I pulled the info for the 500 and 800 models from post 19 to consolidate the info. (07/31/2014)EDIT:Changes to 400 procedure for 800-B/C and 500-B/C
The only real changes are which can capacitor and which section of that can cap to ground to take the measurement off pin 1 of the phase inverter tubes. It's the same section. Depending on which model you have, the B+ will either be 320VDC or 350VDC.
As the 2nd option is the most efficacious for those of us who are technically challenged, we'll use that one for all of the following models.
POWER OFF, PLUG BAGGED!!!! (this keeps you vertical!)
800-C STAND-ALONE SERVICE MANUAL ALL VERSIONS
1.) Ground C87C and follow the rest of the directions. C87C is the 350V B+. (Marker B3 at capacitor and B1 at V12)
EXECUTIVE VIII Model 950 (800-C Serial 10001-19999)
Procedure is same as Standalone 800-C. B+ on C87C is 320V tho.
EXECUTIVE IX Model 960 (No Serial noted on manual).
Procedure is same as Standalone 800-C. B+ on C87C is back up to 350VDC.
500-C 30001-49999 manual
Ground C91C(350V B+) and follow directions outlined in POST #1
