Need Help Finishing Fisher TFM-300 Restoration

artsybob

AK Subscriber
Subscriber
So far I've replaced nearly all the capacitors in this tuner, but I need help replacing the last remaining can cap, replacing the selenium rectifier and testing it to see if the other parts work fine. Does anyone know of someone in the DC/Virginia/Maryland area that can help out? Thanks!
 
The rectifier should have 4 leads. 2 are marked ~ for AC voltage from the transformer, 1 marked - and 1 marked +. The new rectifier is marked the same way. It should be at least rated for 400v 4A. Just connect the new one the same way as the old one. The - lead is chassis ground, + goes to the caps, and the 2 marked ~ are from the transformer.

Which can cap are you having problems with? C2? It's supposed to be a 3 section 50uf /50uf/50uf. There are 2- 390ohm between sections. Section one(C2A) is connected to the rectifier, and the voltage charges that section and thru the 390ohm to section 2 and then thru another 390ohm to section 3. 2 wires come off the 2nd section (C2B) and 3rd Section (C2C). See Diagram below for info. The resistors shown (R7 and R9) may be on the can cap or on a terminal strip further down with plain wire on the cap. But electrically it's the same. R7 is a 470ohm (probably a 1 or 2 watt) and R9 is a 560ohm (probably 1 or 2 w). The manual doesn't say.
NOTE: NOT SURE ABOUT WIRING POSITIONS on NEW RECTIFIER. BUT THEY ARE MARKED. Double check MARKINGS ON NEW RECTIFIER.
TFM 300 POWER SUPPLY.JPG
 
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