Been trying to troubleshoot a "NO FM" problem in this 23-R Receiver for my R-494 Console.
It works fine in AM, Phono, Aux, ALL FUNCTIONS Except FM.
I've replaced the MOSFETS, and the other Transistor in the RF Board. I ruled out the IF due to the AM working and that the FM side hasa lot of common parts. I did re-cap the complete unit(every Electrolytic cap in the receiver). All resistors were checked and any out of spec by more than 5% were replaced. The IC's on the IF Board were replaced.
All voltages on all schematics were checked against receiver. No anomolies.
I finally overcame my fear of pulling the RF Board and did it. Checked all items on it as best i could. All Ceramics were within 3% of rating. Replaced 4 resistors that were >5%. (My replacement tolerance is low). Replaced the one e-lytic. R-504 is being replaced with a 2.7K instead of the lash up that is there now even tho it is in spec.
There are 4 capacitors (1 looks like a wirewound C-513 and the others look like foilpacs) that are WAY OUT OF SPEC.
capacitor Factory Value Actual
C516 27pf 150pf
C518 36pf 68pf
C519 330pf 580pf
c513 5pf 90pf
I'd like to replace with same type but am having problems finding them. My BIG QUESTIONS. Can I replace these with ceramics??? If not then where can I get those caps in those values?
See Pic and Schematic
IMG]http://i408.photobucket.com/albums/pp168/torskdoc/FISHER175-TFMRFBOARDSchematic.jpg[/IMG]
Thanks for any help and suppliers
It works fine in AM, Phono, Aux, ALL FUNCTIONS Except FM.
I've replaced the MOSFETS, and the other Transistor in the RF Board. I ruled out the IF due to the AM working and that the FM side hasa lot of common parts. I did re-cap the complete unit(every Electrolytic cap in the receiver). All resistors were checked and any out of spec by more than 5% were replaced. The IC's on the IF Board were replaced.
All voltages on all schematics were checked against receiver. No anomolies.
I finally overcame my fear of pulling the RF Board and did it. Checked all items on it as best i could. All Ceramics were within 3% of rating. Replaced 4 resistors that were >5%. (My replacement tolerance is low). Replaced the one e-lytic. R-504 is being replaced with a 2.7K instead of the lash up that is there now even tho it is in spec.
There are 4 capacitors (1 looks like a wirewound C-513 and the others look like foilpacs) that are WAY OUT OF SPEC.
capacitor Factory Value Actual
C516 27pf 150pf
C518 36pf 68pf
C519 330pf 580pf
c513 5pf 90pf
I'd like to replace with same type but am having problems finding them. My BIG QUESTIONS. Can I replace these with ceramics??? If not then where can I get those caps in those values?
See Pic and Schematic
IMG]http://i408.photobucket.com/albums/pp168/torskdoc/FISHER175-TFMRFBOARDSchematic.jpg[/IMG]
Thanks for any help and suppliers
