Fisher R-3 Phono preamp sputters / cuts out

zeffer1940

Active Member
Hey Larry and Fisher Gang..I am runnin an R-3, I recapped it last
year and have many hours of no issue use till recently. The phono input sputters fade and falls silent-I switch to radio, tv / aux input no issue. I pop the phono input in out and reinstall it restores sound immediately. I double checked and cleaned rca jacks again, changed turntable, replaced 12ax7 and 12au7 just cause--no help. Today
when it happened, I cut power briefly, off/on, sound restored.....Bad solder joint ?
I also think this unit has somewhat excessive white noise, "rushing" in all modes. Sound is great, clear clean free of distortion...I am playing it for hours even with this occasional issue. Unit is in my Coronet and a chore to remove....any suggestions??fisher lvr model r3.jpg
 
Sounds like a loose connection in your RCA Jacks. Replace them as they DO get loose and they lose connections. The R-3 doesn't have a RIAA PREAMP per se IIRC but it amplifies the signal thru the 12at7. Check all the resistors and caps surrounding the tube also.

There are some "mods" you can do to stabilize the output section. I'll get on my other computer and upload the R-3 mods page of the manual and this one will have the mods on it at the bottom that Dave G ginned up. Mine has come around 180* due to this. Rushing noise could be your using 12ax7 and 12au7? There is no 12ax7 in the R-3. Look at the schematic and tube sheet in the manual. V-18 is the Phono stage. It's a 12at7. The driver for the 4 6v6's is a 12au7. Make sure you have the RIGHT TUBES IN THERE. If you have a 12ax7 in there replace it with the correct tube. That should knock down a good portion of the rushing noises.

Plus there are a couple of threads I did on different problems on my R-3 including the Variable tuning cap shedding plates and my efforts to get a handle on it.
This one is the original thread on mine
http://www.audiokarma.org/forums/index.php?threads/what-was-that-masked-console-in-d-c.398119/
This one details Dave's mods at post 30, but read the whole thread. About 12 resistors to install. And that's it.
http://audiokarma.org/forums/index.php?threads/startup-hum-on-r-3.620577/page-2
More R-3 repairs.........
http://audiokarma.org/forums/index.php?threads/more-r-3-repairs.689912/
Tuner problems in AM
http://audiokarma.org/forums/index.php?threads/r-3-tuner-problem-in-am.617739/

Check all the resistors around the 12au7 driver, replace if 5% out. Then add the cathode, grid and screen resistors as Dave outlines. It should quiet it down considerably and make it more stable even with mismatched tubes in it.
 
Thanks, I do have the correct 12at7 as gain is much diff, and I swapped 12at7 and 12au7 for
new high quality units..I miss typed..I will update asap!
Much appreciate your assistance--need to chk as aforementioned..

jeff
 
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